HP 5920 User manual

HP 5920 & 5900 Switch Series
Layer 3 - IP Services
Configuration Guide
Part number: 5998-2894
Software version: Release2207
Document version: 6W100-20121130

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Contents
Configuring ARP··························································································································································· 1
Overview············································································································································································1
ARP message format ················································································································································1
ARP operating mechanism ······································································································································1
ARP table···································································································································································2
Configuring a static ARP entry·········································································································································3
Configuring a multiport ARP entry···································································································································4
Configuring the maximum number of dynamic ARP entries ·························································································4
Setting the aging timer for dynamic ARP entries ···········································································································5
Enabling dynamic ARP entry check ································································································································5
Displaying and maintaining ARP·····································································································································6
Static ARP configuration example ···································································································································6
Network requirements··············································································································································6
Configuration procedure ·········································································································································7
Multiport ARP entry configuration example····················································································································7
Network requirements··············································································································································7
Configuration procedure ·········································································································································8
Configuring gratuitous ARP ·······································································································································10
Overview········································································································································································· 10
Gratuitous ARP packet learning··························································································································· 10
Periodic sending of gratuitous ARP packets ······································································································· 10
Configuration procedure··············································································································································· 11
Configuring proxy ARP··············································································································································12
Enabling common proxy ARP ······································································································································· 12
Enabling local proxy ARP·············································································································································· 12
Displaying proxy ARP···················································································································································· 12
Common proxy ARP configuration example··············································································································· 13
Network requirements··········································································································································· 13
Configuration procedure ······································································································································ 13
Configuring ARP snooping········································································································································14
Configuration procedure··············································································································································· 14
Displaying and maintaining ARP snooping ················································································································ 14
Configuring IP addressing·········································································································································15
Overview········································································································································································· 15
IP address classes·················································································································································· 15
Special IP addresses ············································································································································· 16
Subnetting and masking ······································································································································· 16
Assigning an IP address to an interface ······················································································································ 17
Configuration guidelines ······································································································································ 17
Configuration procedure ······································································································································ 17
Configuring IP unnumbered ·········································································································································· 17
Configuration guidelines ······································································································································ 17
Configuration prerequisites ·································································································································· 18
Configuration procedure ······································································································································ 18
Displaying and maintaining IP addressing ················································································································· 18
IP address configuration example ································································································································ 18
Network requirements··········································································································································· 18

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Configuration procedure ······································································································································ 19
Verifying the configuration··································································································································· 19
DHCP overview ··························································································································································21
DHCP address allocation ·············································································································································· 21
Allocation mechanisms ········································································································································· 21
Dynamic IP address allocation process··············································································································· 22
IP address lease extension···································································································································· 22
DHCP message format··················································································································································· 23
DHCP options ································································································································································· 24
Common DHCP options········································································································································ 24
Custom DHCP options··········································································································································· 24
Protocols and standards ················································································································································ 26
Configuring the DHCP server····································································································································27
Overview········································································································································································· 27
DHCP address pool··············································································································································· 27
IP address allocation sequence···························································································································· 28
DHCP server configuration task list ······························································································································ 29
Configuring an address pool on the DHCP server····································································································· 29
Configuration task list ··········································································································································· 29
Creating a DHCP address pool··························································································································· 30
Specifying IP address ranges for a DHCP address pool ·················································································· 30
Configuring gateways for the client ···················································································································· 33
Configuring a domain name suffix for the client ······························································································· 34
Configuring DNS servers for the client ··············································································································· 34
Configuring WINS servers and NetBIOS node type for the client ·································································· 34
Configuring BIMS server information for the client···························································································· 35
Configuring the TFTP server and boot file name for the client ········································································· 35
Specifying a server for the DHCP client·············································································································· 36
Configuring Option 184 parameters for the client···························································································· 36
Configuring self-defined DHCP options ·············································································································· 37
Enabling DHCP ······························································································································································ 38
Enabling the DHCP server on an interface·················································································································· 38
Applying an address pool on an interface ················································································································· 38
Configuring IP address conflict detection···················································································································· 39
Enabling handling of Option 82·································································································································· 39
Configuring DHCP server compatibility······················································································································· 40
Configuring the DHCP server to broadcast all responses················································································· 40
Configure the DHCP server to ignore BOOTP requests ···················································································· 40
Configuring the DHCP server to send BOOTP responses in the format specified in RFC 1048 ·················· 40
Displaying and maintaining the DHCP server ············································································································ 41
DHCP server configuration examples ·························································································································· 41
Static IP address assignment configuration example························································································· 42
Dynamic IP address assignment configuration example··················································································· 43
DHCP user class configuration example············································································································· 44
Self-defined option configuration example········································································································· 46
Troubleshooting DHCP server configuration ··············································································································· 46
Symptom································································································································································· 46
Analysis ·································································································································································· 47
Solution··································································································································································· 47
Configuring the DHCP relay agent···························································································································48
Overview········································································································································································· 48
Operation······························································································································································· 48
DHCP relay agent support for Option 82 ·········································································································· 49

iii
DHCP relay agent configuration task list····················································································································· 49
Enabling DHCP ······························································································································································ 50
Enabling the DHCP relay agent on an interface ········································································································ 50
Specifying DHCP servers on a relay agent················································································································· 50
Configuring the DHCP relay agent security functions ································································································ 51
Enabling the DHCP relay agent to record relay entries ···················································································· 51
Enabling periodic refresh of dynamic relay entries··························································································· 51
Enabling DHCP starvation attack protection ······································································································ 52
Configuring the DHCP relay agent to release an IP address ···················································································· 52
Configuring Option 82 ················································································································································· 53
Displaying and maintaining the DHCP relay agent ··································································································· 53
DHCP relay agent configuration examples················································································································· 54
DHCP relay agent configuration example·········································································································· 54
Option 82 configuration example······················································································································· 55
Troubleshooting DHCP relay agent configuration······································································································ 55
Symptom································································································································································· 55
Analysis ·································································································································································· 55
Solution··································································································································································· 56
Configuring the DHCP client ·····································································································································57
Enabling the DHCP client on an interface··················································································································· 57
Configuring a DHCP client ID for an interface ··········································································································· 57
Enabling duplicated address detection ······················································································································· 58
Displaying and maintaining the DHCP client·············································································································· 58
DHCP client configuration example ····························································································································· 58
Network requirements··········································································································································· 58
Configuration procedure ······································································································································ 59
Verifying the configuration··································································································································· 60
Configuring DHCP snooping·····································································································································61
Overview········································································································································································· 61
Application of trusted and untrusted ports·········································································································· 61
DHCP snooping support for Option 82·············································································································· 62
DHCP snooping configuration task list ························································································································ 63
Configuring basic DHCP snooping······························································································································ 63
Configuring Option 82 ················································································································································· 64
Saving DHCP snooping entries ···································································································································· 65
Enabling DHCP starvation attack protection ··············································································································· 66
Enabling DHCP-REQUEST attack protection ··············································································································· 66
Configuring DHCP packet rate limit····························································································································· 67
Displaying and maintaining DHCP snooping ············································································································· 67
DHCP snooping configuration examples····················································································································· 68
Basic DHCP snooping configuration example ··································································································· 68
Option 82 configuration example······················································································································· 69
Configuring the BOOTP client···································································································································71
BOOTP application························································································································································ 71
Obtaining an IP address dynamically ························································································································· 71
Protocols and standards ················································································································································ 71
Configuring an interface to use BOOTP for IP address acquisition·········································································· 71
Displaying and maintaining BOOTP client ················································································································· 72
BOOTP client configuration example ·························································································································· 72
Network requirements··········································································································································· 72
Configuration procedure ······································································································································ 72

iv
Configuring DNS ·······················································································································································73
Overview········································································································································································· 73
Static domain name resolution····························································································································· 73
Dynamic domain name resolution······················································································································· 73
DNS proxy ····························································································································································· 74
DNS spoofing ························································································································································ 75
DNS configuration task list············································································································································ 76
Configuring the IPv4 DNS client ·································································································································· 76
Configuring static domain name resolution········································································································ 76
Configuring dynamic domain name resolution·································································································· 77
Configuring the IPv6 DNS client ·································································································································· 77
Configuring static domain name resolution········································································································ 77
Configuring dynamic domain name resolution·································································································· 78
Configuring the DNS proxy ·········································································································································· 79
Configuring DNS spoofing ··········································································································································· 79
Specifying the source interface for DNS packets ······································································································· 80
Configuring the DNS trusted interface················································································································ 80
Displaying and maintaining IPv4 DNS························································································································ 81
IPv4 DNS configuration examples ······························································································································· 81
Static domain name resolution configuration example ····················································································· 81
Dynamic domain name resolution configuration example ··············································································· 82
DNS proxy configuration example······················································································································ 84
IPv6 DNS configuration examples ······························································································································· 86
Static domain name resolution configuration example ····················································································· 86
Dynamic domain name resolution configuration example ··············································································· 86
DNS proxy configuration example······················································································································ 91
Troubleshooting IPv4 DNS configuration ···················································································································· 92
Symptom································································································································································· 92
Solution··································································································································································· 92
Troubleshooting IPv6 DNS configuration ···················································································································· 92
Symptom································································································································································· 92
Solution··································································································································································· 92
Configuring DDNS·····················································································································································93
Overview········································································································································································· 93
DDNS application ················································································································································· 93
DDNS client configuration task list······························································································································· 94
Configuring a DDNS policy·········································································································································· 94
Configuration prerequisites ·································································································································· 95
Configuration procedure ······································································································································ 95
Applying the DDNS policy to an interface·················································································································· 96
Displaying DDNS··························································································································································· 97
DDNS configuration examples ····································································································································· 97
DDNS configuration example 1 ·························································································································· 97
DDNS configuration example 2 ·························································································································· 98
Basic IP forwarding on the device ························································································································· 100
FIB table ········································································································································································100
Displaying FIB table entries·········································································································································100
Optimizing IP performance ···································································································································· 102
Enabling an interface to receive and forward directed broadcasts destined for the directly connected network
·······················································································································································································102
Configuration procedure ····································································································································102
Configuration example ·······································································································································102
Configuring MTU for an interface ······························································································································103

v
Configuring TCP MSS for an interface ······················································································································103
Configuring TCP path MTU discovery ·······················································································································104
Enabling TCP SYN Cookie··········································································································································105
Configuring the TCP buffer size··································································································································105
Configuring TCP timers················································································································································105
Enabling sending ICMP error packets ·······················································································································106
Functions of sending ICMP error packets ·········································································································106
Disadvantages of sending ICMP error packets································································································107
Configuration procedure ····································································································································107
Disabling forwarding ICMP fragments ······················································································································108
Displaying and maintaining IP performance optimization ······················································································108
Configuring UDP helper·········································································································································· 109
Overview·······································································································································································109
Configuration guidelines ·············································································································································109
Configuration procedure·············································································································································109
Displaying and maintaining UDP helper ···················································································································110
UDP helper configuration example ····························································································································110
Network requirements·········································································································································110
Configuration procedure ····································································································································110
Verifying the configuration·································································································································111
Configuring basic IPv6 settings······························································································································ 112
Overview·······································································································································································112
IPv6 features·························································································································································112
IPv6 addresses·····················································································································································113
IPv6 ND protocol·················································································································································115
IPv6 path MTU discovery····································································································································117
IPv6 transition technologies·········································································································································118
Dual stack·····························································································································································118
Tunneling······························································································································································118
Protocols and standards ··············································································································································118
IPv6 basics configuration task list·······························································································································119
Assigning IPv6 addresses to interfaces······················································································································119
Configuring an IPv6 global unicast address ····································································································120
Configuring an IPv6 link-local address ·············································································································120
Configuring an IPv6 anycast address ···············································································································121
Configuring IPv6 ND ···················································································································································122
Configuring a static neighbor entry ··················································································································122
Configuring the maximum number of neighbors dynamically learned ·························································122
Setting the aging timer for ND entries in stale state························································································123
Minimizing link-local ND entries························································································································123
Setting the hop limit ············································································································································123
Configuring parameters for RA messages········································································································124
Configuring the maximum number of attempts to send an NS message for DAD·······································126
Configuring path MTU discovery ·······························································································································126
Configuring the interface MTU ··························································································································126
Configuring a static path MTU for a specific IPv6 address ············································································127
Configuring the aging time for dynamic path MTUs·······················································································127
Controlling sending ICMPv6 packets·························································································································127
Enabling replying to multicast echo requests ···································································································127
Enabling sending ICMPv6 destination unreachable messages······································································128
Enabling sending ICMPv6 time exceeded messages ······················································································128
Enabling sending ICMPv6 redirect messages ··································································································129
Displaying and maintaining IPv6 basics ···················································································································129

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IPv6 basics configuration example ····························································································································130
Network requirements·········································································································································130
Configuration procedure ····································································································································131
Verifying the configuration·································································································································131
Troubleshooting IPv6 basics configuration················································································································135
Symptom·······························································································································································135
Solution·································································································································································135
DHCPv6 overview··················································································································································· 136
DHCPv6 address/prefix assignment··························································································································136
Rapid assignment involving two messages·······································································································136
Assignment involving four messages·················································································································136
Address/prefix lease renewal ····································································································································137
Stateless DHCPv6·························································································································································138
Protocols and standards ··············································································································································138
Configuring the DHCPv6 server····························································································································· 139
Overview·······································································································································································139
IPv6 address assignment ····································································································································139
IPv6 prefix assignment········································································································································139
Concepts·······························································································································································140
DHCPv6 address pool ········································································································································141
IPv6 address/prefix allocation sequence ·········································································································142
Configuration task list ··················································································································································142
Configuring IPv6 prefix assignment ···························································································································142
Configuration guidelines ····································································································································142
Configuration procedure ····································································································································143
Configuring IPv6 address assignment························································································································143
Configuration guidelines ····································································································································144
Configuration procedure ····································································································································144
Configuring network parameters assignment ···········································································································145
Configuring the DHCPv6 server on an interface ······································································································146
Configuration guidelines ····································································································································146
Configuration procedure ····································································································································146
Displaying and maintaining the DHCPv6 server ······································································································146
DHCPv6 server configuration examples····················································································································147
Dynamic IPv6 prefix assignment configuration example ················································································147
Dynamic IPv6 address assignment configuration example·············································································150
Configuring tunneling ············································································································································· 152
Overview·······································································································································································152
IPv6 over IPv4 tunneling ·····································································································································152
IPv4 over IPv4 tunneling ·····································································································································154
IPv4 over IPv6 tunneling ·····································································································································155
IPv6 over IPv6 tunneling ·····································································································································156
Protocols and standards ·····································································································································157
Tunneling configuration task list ·································································································································157
Configuring a tunnel interface····································································································································157
Configuring an IPv6 over IPv4 manual tunnel···········································································································158
Configuration example ·······································································································································159
Configuring a 6to4 tunnel···········································································································································161
6to4 tunnel configuration example ···················································································································162
Configuring an ISATAP tunnel ····································································································································164
Configuration example ·······································································································································165
Configuring an IPv4 over IPv4 tunnel ························································································································167
Configuration example ·······································································································································168

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Configuring an IPv4 over IPv6 tunnel ························································································································170
Configuration example ·······································································································································171
Configuring an IPv6 over IPv6 tunnel ························································································································173
Configuration example ·······································································································································175
Displaying and maintaining tunneling configuration ·······························································································177
Troubleshooting tunneling configuration ···················································································································177
Symptom·······························································································································································177
Analysis ································································································································································177
Solution·································································································································································177
Configuring GRE····················································································································································· 178
Overview·······································································································································································178
GRE encapsulation format··································································································································178
GRE encapsulation and de-encapsulation ········································································································179
Protocols and standards ·····································································································································179
Configuring a GRE over IPv4 tunnel ··························································································································179
Configuration prerequisites ································································································································180
Configuration procedure ····································································································································180
Configuring a GRE over IPv6 tunnel ··························································································································182
Configuration prerequisites ································································································································182
Configuration procedure ····································································································································182
Displaying and maintaining GRE·······························································································································183
GRE configuration examples ······································································································································184
GRE over IPv4 configuration example ··············································································································184
GRE over IPv6 configuration example ··············································································································187
Troubleshooting GRE ···················································································································································190
Support and other resources ·································································································································· 191
Contacting HP ······························································································································································191
Subscription service ············································································································································191
Related information······················································································································································191
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Websites·······························································································································································191
Conventions ··································································································································································192
Index ········································································································································································ 194

1
Configuring ARP
This chapter describes how to configure the Address Resolution Protocol (ARP).
Overview
ARP resolves IP addresses into MAC addresses on Ethernet networks.
ARP message format
ARP uses two types of messages: ARP request and ARP reply. Figure 1 shows the format of ARP
request/reply messages. Numbers in the figure refer to field lengths.
Figure 1 ARP message format
•Hardware type—Hardware address type. The value 1 represents Ethernet.
•Protocol type—Type of the protocol address to be mapped. The hexadecimal value 0x0800
represents IP.
•Hardware address length and protocol address length—Length, in bytes, of a hardware address
and a protocol address. For an Ethernet address, the value of the hardware address length field is
6. For an IPv4 address, the value of the protocol address length field is 4.
•OP—Operation code, which describes the type of ARP message. Value 1 represents an ARP request,
and value 2 represents an ARP reply.
•Sender hardware address—Hardware address of the device sending the message.
•Sender protocol address—Protocol address of the device sending the message.
•Target hardware address—Hardware address of the device to which the message is being sent.
•Target protocol address—Protocol address of the device to which the message is being sent.
ARP operating mechanism
As shown in Figure 2, Host A and Host B are on the same subnet. Host A sends a packet to Host B as
follows:
1. Host A looks through the ARP table for an ARP entry for Host B. If one entry is found, Host A uses
the MAC address in the entry to encapsulate the IP packet into a data link layer frame. Then Host
A sends the frame to Host B.