HP 6125XLG User manual
HP 6125XLG Blade Switch
Layer 3—IP Routing
Configuration Guide
Part number: 5998-3719
Software version: Rlease 2306
Document version: 6W100-20130912
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Contents
IP routing basics ··························································································································································· 1
Routing table······································································································································································1
Dynamic routing protocols ···············································································································································2
Route preference ·······························································································································································2
Load sharing······································································································································································3
Route backup·····································································································································································3
Route recursion··································································································································································3
Route redistribution ···························································································································································3
Configuring the maximum number of ECMP routes ······································································································4
Displaying and maintaining a routing table ··················································································································4
Configuring static routing············································································································································ 6
Configuring a static route·················································································································································6
Configuring BFD for static routes·····································································································································7
Bidirectional control mode ······································································································································7
Single-hop echo mode ·············································································································································8
Configuring static route FRR·············································································································································9
Configuration guidelines ·········································································································································9
Configuration procedure ·········································································································································9
Displaying and maintaining static routes ···················································································································· 10
Static route configuration examples····························································································································· 10
Basic static route configuration example ············································································································ 10
BFD for static routes configuration example (direct next hop)·········································································· 12
BFD for static routes configuration example (indirect next hop)······································································· 14
Static route FRR configuration example ·············································································································· 17
Configuring a default route·······································································································································19
Configuring RIP ··························································································································································20
Overview········································································································································································· 20
RIP route entries ····················································································································································· 20
Routing loop prevention········································································································································ 20
RIP operation·························································································································································· 20
RIP versions ···························································································································································· 21
Protocols and standards ······································································································································· 21
RIP configuration task list··············································································································································· 21
Configuring basic RIP ···················································································································································· 22
Enabling RIP ··························································································································································· 22
Controlling RIP reception and advertisement on interfaces ·············································································· 23
Configuring a RIP version····································································································································· 23
Configuring RIP route control········································································································································ 24
Configuring an additional routing metric ··········································································································· 24
Configuring RIPv2 route summarization·············································································································· 25
Disabling host route reception ····························································································································· 26
Advertising a default route ··································································································································· 26
Configuring received/redistributed route filtering ····························································································· 27
Configuring a preference for RIP ························································································································· 27
Configuring RIP route redistribution····················································································································· 27
Tuning and optimizing RIP networks ···························································································································· 28
Configuration prerequisites ·································································································································· 28
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Configuring RIP timers··········································································································································· 28
Configuring split horizon and poison reverse···································································································· 29
Configuring the maximum number of ECMP routes ·························································································· 29
Enabling zero field check on incoming RIPv1 messages ·················································································· 30
Enabling source IP address check on incoming RIP updates············································································ 30
Configuring RIPv2 message authentication ········································································································ 31
Configuring the RIP packet sending rate ············································································································ 31
Configuring RIP GR························································································································································ 31
Configuring BFD for RIP················································································································································· 32
Configuring RIP FRR ······················································································································································· 32
Displaying and maintaining RIP ··································································································································· 33
RIP configuration examples··········································································································································· 34
Configuring basic RIP ··········································································································································· 34
Configuring RIP route redistribution····················································································································· 36
Configuring an additional metric for a RIP interface························································································· 38
Configuring RIP to advertise a summary route··································································································· 40
Configuring BFD for RIP (single-hop echo detection)························································································· 42
Configuring RIP FRR ·············································································································································· 45
Configuring OSPF ······················································································································································48
Overview········································································································································································· 48
OSPF packets························································································································································· 48
LSA types································································································································································ 49
OSPF areas ···························································································································································· 49
Router types···························································································································································· 51
Route types····························································································································································· 52
Route calculation ··················································································································································· 53
OSPF network types ·············································································································································· 53
DR and BDR ··························································································································································· 53
Protocols and standards ······································································································································· 54
OSPF configuration task list ·········································································································································· 55
Enabling OSPF ······························································································································································· 56
Configuration prerequisites ·································································································································· 56
Configuration guidelines ······································································································································ 56
Configuration procedure ······································································································································ 57
Configuring OSPF areas ··············································································································································· 57
Configuring a stub area ······································································································································· 58
Configuring an NSSA area·································································································································· 58
Configuring a virtual link······································································································································ 59
Configuring OSPF network types ································································································································· 59
Configuration prerequisites ·································································································································· 60
Configuring the broadcast network type for an interface················································································· 60
Configuring the NBMA network type for an interface ······················································································ 60
Configuring the P2MP network type for an interface························································································ 61
Configuring the P2P network type for an interface ··························································································· 62
Configuring OSPF route control ··································································································································· 62
Configuration prerequisites ·································································································································· 62
Configuring OSPF route summarization ············································································································· 62
Configuring inbound OSPF route filtering ·········································································································· 63
Configuring Type-3 LSA filtering·························································································································· 64
Configuring an OSPF cost for an interface ········································································································ 64
Configuring the maximum number of ECMP routes ·························································································· 65
Configuring OSPF preference······························································································································ 65
Configuring OSPF route redistribution ················································································································ 66
Advertising a host route········································································································································ 67
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Tuning and optimizing OSPF networks························································································································ 67
Configuration prerequisites ·································································································································· 67
Configuring OSPF timers ······································································································································ 68
Specifying LSA transmission delay ······················································································································ 68
Specifying SPF calculation interval······················································································································ 69
Specifying the LSA arrival interval······················································································································· 69
Specifying the LSA generation interval ··············································································································· 70
Disabling interfaces from receiving and sending OSPF packets······································································ 70
Configuring stub routers ······································································································································· 71
Configuring OSPF authentication ························································································································ 71
Adding the interface MTU into DD packets········································································································ 72
Configuring the maximum number of external LSAs in LSDB ··········································································· 72
Configuring OSPF exit overflow interval············································································································· 73
Enabling compatibility with RFC 1583··············································································································· 73
Logging neighbor state changes·························································································································· 73
Configuring OSPF network management ··········································································································· 74
Configuring the LSU transmit rate························································································································ 74
Enabling OSPF ISPF ·············································································································································· 75
Configuring OSPF GR ··················································································································································· 75
Configuring the OSPF GR Restarter····················································································································· 75
Configuring OSPF GR Helper ······························································································································ 76
Triggering OSPF GR ············································································································································· 77
Configuring BFD for OSPF ············································································································································ 77
Configuring bidirectional control detection········································································································ 77
Configuring single-hop echo detection ··············································································································· 78
Configuring OSPF FRR··················································································································································· 78
Configuration prerequisites ·································································································································· 79
Configuration guidelines ······································································································································ 79
Configuring OSPF FRR to calculate a backup next hop using the LFA algorithm ·········································· 79
Configuring OSPF FRR to specify a backup next hop using a routing policy················································· 79
Displaying and maintaining OSPF······························································································································· 80
OSPF configuration examples ······································································································································ 81
Configuring basic OSPF ······································································································································· 81
Configuring OSPF route redistribution ················································································································ 84
Configuring OSPF to advertise a summary route······························································································· 85
Configuring an OSPF stub area··························································································································· 88
Configuring an OSPF NSSA area······················································································································· 91
Configuring OSPF DR election····························································································································· 93
Configuring OSPF virtual links ····························································································································· 97
Configuring OSPF GR··········································································································································· 99
Configuring BFD for OSPF ·································································································································101
Configuring OSPF FRR········································································································································104
Troubleshooting OSPF configuration ·························································································································106
No OSPF neighbor relationship established ····································································································106
Incorrect routing information ······························································································································107
Configuring IS-IS ····················································································································································· 108
Overview·······································································································································································108
Terminology ·························································································································································108
IS-IS address format·············································································································································108
NET ·······································································································································································109
IS-IS area ······························································································································································110
IS-IS network types ··············································································································································112
IS-IS PDUs ·····························································································································································113
Protocols and standards ·····································································································································114
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IS-IS configuration task list···········································································································································115
Configuring basic IS-IS ················································································································································116
Configuration prerequisites ································································································································116
Enabling IS-IS·······················································································································································116
Configuring the IS level and circuit level ··········································································································116
Configuring P2P network type for an interface································································································117
Configuring IS-IS route control····································································································································117
Configuration prerequisites ································································································································117
Configuring IS-IS link cost···································································································································118
Specifying a preference for IS-IS ·······················································································································119
Configuring the maximum number of ECMP routes ························································································119
Configuring IS-IS route summarization··············································································································120
Advertising a default route ·································································································································120
Configuring IS-IS route redistribution ················································································································121
Configuring IS-IS route filtering··························································································································121
Configuring IS-IS route leaking ··························································································································122
Tuning and optimizing IS-IS networks ························································································································122
Configuration prerequisites ································································································································122
Specifying intervals for sending IS-IS hello and CSNP packets ·····································································123
Specifying the IS-IS hello multiplier····················································································································123
Configuring a DIS priority for an interface·······································································································123
Disabling an interface from sending/receiving IS-IS packets·········································································124
Enabling an interface to send small hello packets···························································································124
Configuring LSP parameters·······························································································································124
Controlling SPF calculation interval···················································································································127
Configuring convergence priorities for specific routes····················································································127
Setting the LSDB overload bit·····························································································································128
Configuring system ID to host name mappings································································································128
Enabling the logging of neighbor state changes·····························································································129
Enabling IS-IS ISPF···············································································································································130
Enhancing IS-IS network security ································································································································130
Configuration prerequisites ································································································································130
Configuring neighbor relationship authentication ···························································································130
Configuring area authentication························································································································131
Configuring routing domain authentication······································································································131
Configuring IS-IS GR····················································································································································132
Configuring BFD for IS-IS·············································································································································133
Configuring IS-IS FRR ···················································································································································133
Configuration prerequisites ································································································································134
Configuration guidelines ····································································································································134
Configuring IS-IS FRR to automatically calculate a backup next hop ····························································134
Configuring IS-IS FRR using a routing policy····································································································134
Displaying and maintaining IS-IS ·······························································································································135
IS-IS configuration examples·······································································································································135
Basic IS-IS configuration example ·····················································································································135
DIS election configuration example···················································································································140
IS-IS route redistribution configuration example ······························································································144
IS-IS authentication configuration example·······································································································147
IS-IS GR configuration example ·························································································································150
BFD for IS-IS configuration example··················································································································151
IS-IS FRR configuration example ························································································································154
Configuring BGP ····················································································································································· 158
Overview·······································································································································································158
BGP speaker and BGP peer·······························································································································158
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BGP message types·············································································································································158
BGP path attributes ·············································································································································159
BGP route selection ·············································································································································163
BGP route advertisement rules ···························································································································163
BGP load balancing············································································································································163
Settlements for problems in large-scale BGP networks····················································································164
MP-BGP·································································································································································167
BGP configuration views ····································································································································168
Protocols and standards ·····································································································································169
BGP configuration task list ··········································································································································169
Configuring basic BGP················································································································································172
Enabling BGP·······················································································································································172
Configuring a BGP peer·····································································································································173
Configuring a BGP peer group··························································································································174
Specifying the source interface for TCP connections·······················································································179
Generating BGP routes················································································································································180
Injecting a local network ····································································································································181
Redistributing IGP routes·····································································································································181
Controlling route distribution and reception ·············································································································182
Configuring BGP route summarization ·············································································································183
Advertising optimal routes in the IP routing table ····························································································184
Advertising a default route to a peer or peer group ·······················································································184
Limiting routes received from a peer or peer group························································································185
Configuring BGP route filtering policies ···········································································································186
Configuring BGP route dampening···················································································································191
Controlling BGP path selection···································································································································192
Specifying a preferred value for routes received·····························································································192
Configuring preferences for BGP routes ···········································································································193
Configuring the default local preference ··········································································································194
Configuring the MED attribute ···························································································································195
Configuring the NEXT_HOP attribute················································································································199
Configuring the AS_PATH attribute ···················································································································201
Tuning and optimizing BGP networks························································································································206
Configuring the keepalive interval and hold time····························································································206
Configuring the interval for sending updates for the same route···································································207
Enabling BGP to establish an EBGP session over multiple hops ····································································208
Enabling immediate reestablishment of direct EBGP connections upon link failure·····································209
Enabling 4-byte AS number suppression ··········································································································209
Configuring MD5 authentication for BGP ········································································································210
Configuring BGP load balancing ······················································································································211
Disabling BGP to establish a session to a peer or peer group ······································································212
Configuring BGP soft-reset··································································································································212
Protecting an EBGP peer when memory usage reaches level 2 threshold····················································216
Configuring a large-scale BGP network ····················································································································217
Configuring BGP community······························································································································217
Configuring a BGP route reflector ·····················································································································219
Configuring a BGP confederation ·····················································································································219
Configuring BGP GR ···················································································································································220
Enabling trap································································································································································221
Enabling logging of session state changes ···············································································································222
Configuring BFD for BGP ············································································································································222
Displaying and maintaining BGP·······························································································································223
IPv4 BGP configuration examples ······························································································································226
Basic BGP configuration example ·····················································································································226
vi
BGP and IGP route redistribution configuration example···············································································230
BGP route summarization configuration example ···························································································233
BGP load balancing configuration example ····································································································236
BGP community configuration example············································································································239
BGP route reflector configuration example·······································································································242
BGP confederation configuration example·······································································································244
BGP path selection configuration example·······································································································248
BGP GR configuration example·························································································································252
BFD for BGP configuration example ·················································································································253
IPv6 BGP configuration examples ······························································································································257
IPv6 BGP basic configuration example·············································································································257
IPv6 BGP route reflector configuration example ······························································································260
BFD for IPv6 BGP configuration example ·········································································································263
Troubleshooting BGP ···················································································································································267
Symptom·······························································································································································267
Analysis ································································································································································267
Solution·································································································································································267
Configuring PBR ······················································································································································ 268
Introduction to PBR ·······················································································································································268
Policy ····································································································································································268
PBR and Track······················································································································································269
PBR configuration task list ···········································································································································269
Configuring a policy····················································································································································269
Creating a node ··················································································································································269
Configuring match criteria for a node ··············································································································269
Configuring actions for a node··························································································································270
Configuring PBR ···························································································································································270
Displaying and maintaining PBR ································································································································270
Packet type-based interface PBR configuration example ·························································································271
Network requirements·········································································································································271
Configuration procedure ····································································································································271
Verifying the configuration·································································································································272
Configuring IPv6 static routing······························································································································· 274
Configuring an IPv6 static route ·································································································································274
Configuring BFD for IPv6 static routes ·······················································································································275
Bidirectional control mode ·································································································································275
Single-hop echo mode ········································································································································276
Displaying and maintaining IPv6 static routes··········································································································277
IPv6 static routing configuration examples················································································································277
Basic IPv6 static route configuration example··································································································277
BFD for IPv6 static routes configuration example (direct next hop) ·······························································279
BFD for IPv6 static routes configuration example (indirect next hop) ····························································281
Configuring an IPv6 default route·························································································································· 285
Configuring RIPng ··················································································································································· 286
Overview·······································································································································································286
RIPng route entries···············································································································································286
RIPng packets·······················································································································································286
Protocols and standards ·····································································································································287
RIPng configuration task list ········································································································································287
Configuring basic RIPng··············································································································································287
Configuring RIPng route control ·································································································································288
Configuring an additional routing metric ·········································································································288
vii
Configuring RIPng route summarization ···········································································································288
Advertising a default route ·································································································································289
Configuring received/redistributed route filtering ···························································································289
Configuring a preference for RIPng···················································································································289
Configuring RIPng route redistribution ··············································································································290
Tuning and optimizing the RIPng network·················································································································290
Configuring RIPng timers ····································································································································290
Configuring split horizon and poison reverse··································································································291
Configuring zero field check on RIPng packets ·······························································································291
Configuring the maximum number of ECMP routes ························································································292
Configuring RIPng GR··················································································································································292
Displaying and maintaining RIPng ·····························································································································293
RIPng configuration examples·····································································································································293
Basic RIPng configuration example ···················································································································293
RIPng route redistribution configuration example ····························································································296
Configuring OSPFv3··············································································································································· 299
OSPFv3 overview·························································································································································299
OSPFv3 packets···················································································································································299
OSPFv3 LSA types···············································································································································299
Protocols and standards ·····································································································································300
OSPFv3 configuration task list ····································································································································300
Enabling OSPFv3 ·························································································································································301
Configuring OSPFv3 area parameters ······················································································································302
Configuration prerequisites ································································································································302
Configuring a stub area ·····································································································································302
Configuring an OSPFv3 virtual link···················································································································302
Configuring OSPFv3 network types···························································································································303
Configuration prerequisites ································································································································303
Configuring the OSPFv3 network type for an interface ··················································································303
Configuring an NBMA or P2MP neighbor·······································································································304
Configuring OSPFv3 route control ·····························································································································304
Configuration prerequisites ································································································································304
Configuring OSPFv3 route summarization ·······································································································304
Configuring OSPFv3 received route filtering····································································································305
Configuring Inter-Area-Prefix LSA filtering ········································································································305
Configuring an OSPFv3 cost for an interface ··································································································305
Configuring the maximum number of OSPFv3 ECMP routes ·········································································306
Configuring a preference for OSPFv3 ··············································································································306
Configuring OSPFv3 route redistribution··········································································································307
Tuning and optimizing OSPFv3 networks ·················································································································307
Configuration prerequisites ································································································································307
Configuring OSPFv3 timers································································································································308
Specifying LSA transmission delay ····················································································································308
Specifying SPF calculation interval····················································································································308
Specifying the LSA generation interval ·············································································································309
Configuring a DR priority for an interface········································································································309
Ignoring MTU check for DD packets ·················································································································310
Disabling interfaces from receiving and sending OSPFv3 packets ·······························································310
Enabling the logging of neighbor state changes·····························································································311
Configuring OSPFv3 GR ·············································································································································311
Configuring GR Restarter····································································································································311
Configuring GR Helper·······································································································································312
Configuring BFD for OSPFv3······································································································································312
Displaying and maintaining OSPFv3·························································································································313
viii
OSPFv3 configuration examples ································································································································313
Configuring OSPFv3 areas ································································································································313
Configuring OSPFv3 DR election·······················································································································317
Configuring OSPFv3 route redistribution··········································································································320
Configuring OSPFv3 GR ····································································································································323
Configuring BFD for OSPFv3 ·····························································································································325
Configuring IPv6 IS-IS ············································································································································· 328
Overview·······································································································································································328
Configuring basic IPv6 IS-IS········································································································································328
Configuring IPv6 IS-IS route control ···························································································································329
Configuring BFD for IPv6 IS-IS ····································································································································330
Displaying and maintaining IPv6 IS-IS·······················································································································330
IPv6 IS-IS configuration examples ······························································································································331
IPv6 IS-IS basic configuration example·············································································································331
BFD for IPv6 IS-IS configuration example ·········································································································335
Configuring IPv6 PBR·············································································································································· 338
Introduction to IPv6 PBR···············································································································································338
Policy ····································································································································································338
PBR and Track······················································································································································339
IPv6 PBR configuration task list···································································································································339
Configuring an IPv6 policy ·········································································································································339
Creating an IPv6 node········································································································································339
Configuring match criteria for an IPv6 node····································································································339
Configuring actions for an IPv6 node ···············································································································340
Configuring IPv6 PBR···················································································································································340
Displaying and maintaining IPv6 PBR························································································································340
Packet type-based IPv6 interface PBR configuration example·················································································341
Network requirements·········································································································································341
Configuration procedure ····································································································································341
Verifying the configuration·································································································································342
Configuring routing policies··································································································································· 344
Overview·······································································································································································344
Filters·····································································································································································344
Routing policy ······················································································································································345
Configuring filters·························································································································································345
Configuration prerequisites ································································································································345
Configuring an IP prefix list································································································································345
Configuring an AS path list································································································································346
Configuring a community list ·····························································································································346
Configuring an extended community list ··········································································································347
Configuring a routing policy·······································································································································347
Configuration prerequisites ································································································································347
Creating a routing policy ···································································································································347
Configuring if-match clauses ······························································································································348
Configuring apply clauses··································································································································349
Configuring a continue clause ···························································································································350
Displaying and maintaining the routing policy·········································································································351
Routing policy configuration examples······················································································································351
Applying a routing policy to IPv4 route redistribution·····················································································351
Applying a routing policy to IPv6 route redistribution·····················································································354
Support and other resources ·································································································································· 357
Contacting HP ······························································································································································357
ix
Subscription service ············································································································································357
Related information······················································································································································357
Documents····························································································································································357
Websites·······························································································································································357
Conventions ··································································································································································358
Index ········································································································································································ 360
1
IP routing basics
IP routing directs IP packet forwarding on routers based on a routing table. This chapter focuses on
unicast routing protocols. For more information about multicast routing protocols, see IP Multicast
Configuration Guide.
Routing table
A router maintains at least two routing tables: a global routing table and a FIB. The FIB table contains
only the optimal routes, and the global routing table contains all routes. The router uses the FIB table to
forward packets. For more information about the FIB table, see Layer 3—IP Services Configuration
Guide.
Table 1 categorizes routes by different criteria.
Table 1 Route categories
Criterion Categories
Destination •Network route—The destination is a network. The subnet mask is less than 32 bits.
•Host route—The destination is a host. The subnet mask is 32 bits.
Whether the
destination is directly
connected
•Direct route—The destination is directly connected.
•Indirect route—The destination is indirectly connected.
Origin
•Direct route—A direct route is discovered by the data link protocol on an interface,
and is also called an "interface route."
•Static route—A static route is manually configured by an administrator.
•Dynamic route—A dynamic route is dynamically discovered by a routing protocol.
To view brief information about a routing table, use the display ip routing-table command:
<Sysname> display ip routing-table
Destinations : 19 Routes : 19
Destination/Mask Proto Pre Cost NextHop Interface
0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0
1.1.1.0/24 Direct 0 0 1.1.1.1 Vlan1
1.1.1.0/32 Direct 0 0 1.1.1.1 Vlan1
1.1.1.1/32 Direct 0 0 127.0.0.1 InLoop0
1.1.1.255/32 Direct 0 0 1.1.1.1 Vlan1
2.2.2.0/24 Static 60 0 12.2.2.2 Vlan2
80.1.1.0/24 OSPF 10 2 80.1.1.1 Vlan3
...
A route entry includes the following key items:
•Destination—IP address of the destination host or network.
•Mask—Mask length of the IP address.
2
•Pre—Preference of the route. Among routes to the same destination, the route with the highest
preference is optimal.
•Cost—If multiple routes to a destination have the same preference, the one with the smallest cost is
the optimal route.
•NextHop—Next hop.
•Interface—Output interface.
Dynamic routing protocols
Static routes work well in small, stable networks. They are easy to configure and require fewer system
resources. However, in networks where topology changes occur frequently, a typical practice is to
configure a dynamic routing protocol. Compared with static routing, a dynamic routing protocol is
complicated to configure, requires more routers resources, and consumes more network resources.
Dynamic routing protocols dynamically collect and report reachability information to adapt to topology
changes. They are suitable for large networks.
Dynamic routing protocols can be classified by different criteria, as shown in Table 2.
Table 2 Categories of dynamic routing protocols
Criterion Categories
Operation scope •IGPs—Work within an AS. Examples include RIP, OSPF, and IS-IS.
•EGPs—Work between ASs. The most popular EGP is BGP.
Routing algorithm
•Distance-vector protocols—Examples include RIP and BGP. BGP is also considered
a path-vector protocol.
•Link-state protocols—Examples include OSPF and IS-IS.
Destination address
type
•Unicast routing protocols—Examples include RIP, OSPF, BGP, and IS-IS.
•Multicast routing protocols—Examples include PIM-SM and PIM-DM.
IP version
•IPv4 routing protocols—Examples include RIP, OSPF, BGP, and IS-IS.
•IPv6 routing protocols—Examples include RIPng, OSPFv3, IPv6 BGP, and IPv6 IS-IS.
An AS refers to a group of routers that use the same routing policy and work under the same
administration.
Route preference
Routing protocols, including static and direct routing, each by default have a preference. If they find
multiple routes to the same destination, the router selects the route with the highest preference as the
optimal route.
The preference of a direct route is always 0 and cannot be changed. You can configure a preference for
each static route and each dynamic routing protocol. The following table lists the route types and default
preferences. The smaller the value, the higher the preference.
Table 3 Route types and default route preferences
Route type Preference
Direct route 0
3
Route type Preference
Multicast static route 1
OSPF 10
IS-IS 15
Unicast static route 60
RIP 100
OSPF ASE 150
OSPF NSSA 150
IBGP 255
EBGP 255
Unknown (route from an untrusted source) 256
Load sharing
A routing protocol may find multiple optimal equal-cost routes to the same destination. You can use these
routes to implement equal-cost multi-path (ECMP) load sharing.
Static routing, IPv6 static routing, RIP, RIPng, OSPF, OSPFv3, BGP, IPv6 BGP, IS-IS, and IPv6 IS-IS support
ECMP load sharing.
Route backup
Route backup can improve network availability. Among multiple routes to the same destination, the route
with the highest priority is the primary route and others are secondary routes.
The router forwards matching packets through the primary route. When the primary route fails, the route
with the highest preference among the secondary routes is selected to forward packets. When the
primary route recovers, the router uses it to forward packets.
Route recursion
To use a route that has an indirectly connected next hop, a router must perform route recursion to find the
outgoing interface to reach the next hop.
Route redistribution
Route redistribution enables routing protocols to learn route information from each other. A dynamic
routing protocol can redistribute routes from other routing protocols, including direct and static routing.
For more information, see the respective chapters on those routing protocols in this configuration guide.
4
Configuring the maximum number of ECMP routes
This configuration takes effect at next reboot. Make sure the reboot does not impact your network.
To configure the maximum number of ECMP routes:
Ste
p
Command
Remarks
1. Enter system view. system-view N/A
2. Configure the maximum
number of ECMP routes. max-ecmp-num number By default, the maximum
number of ECMP routes is 8.
3. (Optional.) Display the
maximum number of ECMP
routes.
display max-ecmp-num You can execute the display
command in any view.
Displaying and maintaining a routing table
Execute display commands in any view and reset commands in user view.
Task Command
Display routing table information. display ip routing-table [ vpn-instance vpn-instance-name ]
[ verbose ]
Display information about routes
permitted by an IPv4 basic ACL.
display ip routing-table [ vpn-instance vpn-instance-name ] acl
acl-number [ verbose ]
Display information about routes to a
specific destination address.
display ip routing-table [ vpn-instance vpn-instance-name ]
ip-address [ mask |mask-length ] [ longer-match ] [ verbose ]
Display information about routes to a
range of destination addresses.
display ip routing-table [ vpn-instance vpn-instance-name ]
ip-address1 to ip-address2 [ verbose ]
Display information about routes
permitted by an IP prefix list.
display ip routing-table [ vpn-instance vpn-instance-name ] prefix-list
prefix-list-name [ verbose ]
Display information about routes
installed by a protocol.
display ip routing-table [ vpn-instance vpn-instance-name ] protocol
protocol [ inactive | verbose ]
Display IPv4 route statistics. display ip routing-table [ vpn-instance vpn-instance-name ] statistics
Clear IPv4 route statistics. reset ip routing-table statistics protocol [ vpn-instance
vpn-instance-name ] { protocol |all }
Display IPv6 routing table information.
display ipv6 routing-table [ vpn-instance vpn-instance-name ]
[ verbose ]
Display information about routes to an
IPv6 destination address.
display ipv6 routing-table [ vpn-instance vpn-instance-name ]
ipv6-address [ prefix-length ][ longer-match ] [ verbose ]
Display information about routes
permitted by an IPv6 basic ACL.
display ipv6 routing-table [ vpn-instance vpn-instance-name ] acl
acl6-number [ verbose ]
Display information about routes to a
range of IPv6 destination addresses.
display ipv6 routing-table [ vpn-instance vpn-instance-name ]
ipv6-address1 to ipv6-address2 [ verbose ]
Display information about routes
permitted by an IPv6 prefix list.
display ipv6 routing-table [ vpn-instance vpn-instance-name ]
prefix-list prefix-list-name [ verbose ]
5
Task Command
Display information about routes
installed by an IPv6 protocol.
display ipv6 routing-table [ vpn-instance vpn-instance-name ]
protocol protocol [ inactive | verbose ]
Display IPv6 route statistics. display ipv6 routing-table [ vpn-instance vpn-instance-name ]
statistics
Clear IPv6 route statistics. reset ipv6 routing-table statistics protocol [ vpn-instance
vpn-instance-name ] { protocol |all }
6
Configuring static routing
Static routes are manually configured. If a network's topology is simple, you only need to configure static
routes for the network to work properly.
Static routes cannot adapt to network topology changes. If a fault or a topological change occurs in the
network, the network administrator must modify the static routes manually.
Configuring a static route
Before you configure a static route, complete the following tasks:
•Configure the physical parameters for related interfaces.
•Configure the link-layer attributes for related interfaces.
•Configure the IP addresses for related interfaces.
You can associate track with a static route to monitor the reachability of the next hops. For more
information about track, see High Availability Configuration Guide.
To configure a static route:
Ste
p
Command
Remarks
1. Enter system view. system-view N/A
2. Configure a static
route.
•Method 1:
ip route-static dest-address { mask |
mask-length } { next-hop-address [ track
track-entry-number ] | interface-type
interface-number [ next-hop-address ] |
vpn-instance d-vpn-instance-name
next-hop-address [ track track-entry-number ] }
[ permanent ] [ preference preference-value ]
[ tag tag-value ] [ description description-text ]
•Method 2:
ip route-static vpn-instance
s-vpn-instance-name dest-address { mask |
mask-length } { next-hop-address [ public ]
[ track track-entry-number ] | interface-type
interface-number [ next-hop-address ] |
vpn-instance d-vpn-instance-name
next-hop-address [ track track-entry-number ] }
[ permanent ] [ preference preference-value ]
[ tag tag-value ] [ description description-text ]
Use either method.
By default, no static route is
configured.
3. (Optional.)
Configure the default
preference for static
routes.
ip route-static default-preference
default-preference-value The default setting is 60.
7
Ste
p
Command
Remarks
4. (Optional.) Delete all
static routes,
including the default
route.
delete [ vpn-instance vpn-instance-name ]
static-routes all
To delete one static route,
use the undo ip route-static
command.
Configuring BFD for static routes
IMPORTANT:
Enabling BFD for a flapping route could worsen the situation.
BFD provides a general-purpose, standard, medium-, and protocol-independent fast failure detection
mechanism. It can uniformly and quickly detect the failures of the bidirectional forwarding paths between
two routers for protocols, such as routing protocols.
For more information about BFD, see High Availability Configuration Guide.
Bidirectional control mode
To use BFD bidirectional control detection between two devices, enable BFD control mode for each
device's static route destined to the peer.
To configure a static route and enable BFD control mode for it, specify an output interface and a direct
next hop, or specify an indirect next hop and a specific BFD packet source address for the static route.
To configure BFD control mode for a static route (direct next hop):
Ste
p
Command
Remarks
1. Enter system view. system-view N/A
2. Configure BFD
control mode for a
static route.
•Method 1:
ip route-static dest-address { mask | mask-length }
interface-type interface-number next-hop-address
bfd control-packet [ preference preference-value ]
[tag tag-value ] [ description description-text ]
•Method 2:
ip route-static vpn-instance s-vpn-instance-name
dest-address {mask |mask-length } interface-type
interface-number next-hop-address bfd
control-packet [ preference preference-value ] [ tag
tag-value ] [ description description-text ]
Use either method.
By default, BFD control
mode for a static route is
not configured.
To configure BFD control mode for a static route (indirect next hop):
Ste
p
Command
Remarks
1. Enter system view. system-view N/A
8
Ste
p
Command
Remarks
2. Configure BFD
control mode for a
static route.
•Method 1:
ip route-static dest-address { mask | mask-length }
{ next-hop-address bfd control-packet bfd-source
ip-address | vpn-instance d-vpn-instance-name
next-hop-address bfd control-packet bfd-source
ip-address } [ preference preference-value ] [ tag
tag-value ] [ description description-text ]
•Method 2:
ip route-static vpn-instance s-vpn-instance-name
dest-address {mask | mask-length }
{ next-hop-address bfd control-packet bfd-source
ip-address | vpn-instance d-vpn-instance-name
next-hop-address bfd control-packet bfd-source
ip-address } [ preference preference-value ] [ tag
tag-value ] [ description description-text ]
Use either method.
By default, BFD control
mode for a static route is
not configured.
Single-hop echo mode
With BFD echo mode enabled for a static route, the output interface sends BFD echo packets to the
destination device, which loops the packets back to test the link reachability.
IMPORTANT:
Do not use BFD for a static route with the output interface in spoofing state.
To configure BFD echo mode for a static route:
Ste
p
Command
Remarks
1. Enter system view. system-view N/A
2. Configure the source
address of echo
packets.
bfd echo-source-ip ip-address
By default, the source
address of echo packets is
not configured.
For more information about
this command, see High
Availability Command
Reference.
3. Configure BFD echo
mode for a static
route.
•Method 1:
ip route-static dest-address { mask |
mask-length } interface-type interface-number
next-hop-address bfd echo-packet [ preference
preference-value ] [ tag tag-value ] [ description
description-text ]
•Method 2:
ip route-static vpn-instance
s-vpn-instance-name dest-address { mask |
mask-length } interface-type interface-number
next-hop-address bfd echo-packet [ preference
preference-value ] [ tag tag-value ] [ description
description-text ]
Use either method.
By default, BFD echo mode
for a static route is not
configured.
9
Configuring static route FRR
A link or router failure on a path can cause packet loss and even routing loop. Static route fast reroute
(FRR) enables fast rerouting to minimize the impact of link or node failures.
Figure 1 Network diagram
As shown in Figure 1, upon a link failure, FRR specifies a backup next hop by using a routing policy for
routes matching the specified criteria. Packets are directed to the backup next hop to avoid traffic
interruption.
Configuration guidelines
•Do not use static route FRR and BFD (for a static route) at the same time.
•Static route does not take effect when the backup output interface is unavailable.
•Equal-cost routes do not support FRR.
•The backup output interface and next hop cannot be modified directly or the same as the primary
output interface and next hop.
Configuration procedure
To configure static route FRR:
Ste
p
Command
Remarks
1. Enter system view. system-view N/A
2. Configure the source
address of BFD echo
packets.
bfd echo-source-ip ip-address
By default, the source address
of BFD echo packets is not
configured.
For more information about
this command, see High
Availability Command
Reference.
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