HP 6127XLG Blade Series User manual

HP 6127XLG Blade Switch Series
MPLS
Configuration Guide
Part number: 797711-001
Software version: Release 2418P03
Document version: 6W100-20150806

Legal and notice information
© Copyright 2015 Hewlett-Packard Development Company, L.P.
No part of this documentation may be reproduced or transmitted in any form or by any means without
prior written consent of Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
HEWLETT-PACKARD COMPANY MAKES NO WARRANTY OF ANY KIND WITH REGARD TO THIS
MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE. Hewlett-Packard shall not be liable for errors contained
herein or for incidental or consequential damages in connection with the furnishing, performance, or
use of this material.
The only warranties for HP products and services are set forth in the express warranty statements
accompanying such products and services. Nothing herein should be construed as constituting an
additional warranty. HP shall not be liable for technical or editorial errors or omissions contained
herein.

i
Contents
Configuring basic MPLS ·············································································································································· 1
Overview············································································································································································1
Basic concepts ··························································································································································1
MPLS network architecture ······································································································································3
LSP establishment······················································································································································3
MPLS forwarding ······················································································································································4
PHP·············································································································································································5
Protocols and standards ··········································································································································5
MPLS configuration task list··············································································································································5
Enabling MPLS···································································································································································6
Configuring MPLS MTU ····················································································································································6
Specifying the label type advertised by the egress·······································································································7
Configuring TTL propagation···········································································································································8
Enabling sending of MPLS TTL-expired messages ·········································································································9
Enabling MPLS forwarding statistics ···························································································································· 10
Enabling SNMP notifications for MPLS························································································································ 10
Displaying and maintaining MPLS ······························································································································· 10
Configuring a static LSP·············································································································································12
Overview········································································································································································· 12
Configuration prerequisites··········································································································································· 12
Configuration procedure··············································································································································· 12
Displaying static LSPs····················································································································································· 13
Static LSP configuration example ································································································································· 13
Network requirements··········································································································································· 13
Configuration restrictions and guidelines ··········································································································· 14
Configuration procedure ······································································································································ 14
Verifying the configuration··································································································································· 15
Configuring LDP ·························································································································································16
Overview········································································································································································· 16
Terminology ··························································································································································· 16
LDP messages························································································································································· 16
LDP operation························································································································································· 17
Label distribution and control······························································································································· 18
LDP GR···································································································································································· 20
LDP NSR ································································································································································· 21
LDP-IGP synchronization ······································································································································· 22
LDP FRR··································································································································································· 23
Protocols ································································································································································· 23
LDP configuration task list·············································································································································· 23
Enabling LDP··································································································································································· 24
Enabling LDP globally··········································································································································· 24
Enabling LDP on an interface······························································································································· 24
Configuring Hello parameters ······································································································································ 25
Configuring LDP session parameters···························································································································· 26
Configuring LDP backoff ··············································································································································· 27
Configuring LDP MD5 authentication ·························································································································· 27
Configuring an LSP generation policy ························································································································· 28
Configuring the LDP label distribution control mode·································································································· 28

ii
Configuring a label advertisement policy ··················································································································· 29
Configuring a label acceptance policy ······················································································································· 30
Configuring LDP loop detection···································································································································· 31
Configuring LDP session protection······························································································································ 31
Configuring LDP GR······················································································································································· 32
Configuring LDP NSR····················································································································································· 32
Configuring LDP-IGP synchronization ·························································································································· 32
Configuring LDP-OSPF synchronization ·············································································································· 33
Configuring LDP-ISIS synchronization ················································································································· 34
Configuring LDP FRR ······················································································································································ 35
Resetting LDP sessions···················································································································································· 35
Enabling SNMP notifications for LDP··························································································································· 35
Displaying and maintaining LDP ·································································································································· 35
LDP configuration examples·········································································································································· 36
LDP LSP configuration example···························································································································· 36
Label acceptance control configuration example ······························································································ 40
Label advertisement control configuration example ·························································································· 44
LDP FRR configuration example ··························································································································· 49
Configuring MPLS TE ·················································································································································53
Overview········································································································································································· 53
TE and MPLS TE····················································································································································· 53
MPLS TE basic concepts········································································································································ 53
Static CRLSP establishment ··································································································································· 53
Dynamic CRLSP establishment ····························································································································· 53
Traffic forwarding·················································································································································· 55
Make-before-break ················································································································································ 56
Route pinning························································································································································· 57
Tunnel reoptimization············································································································································ 57
Automatic bandwidth adjustment ························································································································ 57
CRLSP backup························································································································································ 58
FRR ·········································································································································································· 58
DiffServ-aware TE ·················································································································································· 59
Bidirectional MPLS TE tunnel ································································································································ 61
Protocols and standards ······································································································································· 62
MPLS TE configuration task list ····································································································································· 62
Enabling MPLS TE ·························································································································································· 63
Configuring a tunnel interface······································································································································ 64
Configuring DS-TE·························································································································································· 64
Configuring an MPLS TE tunnel to use a static CRLSP································································································ 65
Configuring an MPLS TE tunnel to use a dynamic CRLSP·························································································· 65
Configuration task list ··········································································································································· 66
Configuring MPLS TE attributes for a link ··········································································································· 66
Advertising link TE attributes by using IGP TE extension··················································································· 67
Configuring MPLS TE tunnel constraints·············································································································· 68
Establishing an MPLS TE tunnel by using RSVP-TE ····························································································· 70
Controlling CRLSP path selection························································································································· 70
Controlling MPLS TE tunnel setup ························································································································ 72
Configuring traffic forwarding······································································································································ 75
Configuring static routing to direct traffic to an MPLS TE tunnel ······································································ 75
Configuring automatic route advertisement to direct traffic to an MPLS TE tunnel········································· 75
Configuring a bidirectional MPLS TE tunnel················································································································ 76
Configuring CRLSP backup ··········································································································································· 77
Configuring MPLS TE FRR·············································································································································· 78
Enabling FRR·························································································································································· 78

iii
Configuring a bypass tunnel on the PLR ············································································································· 78
Configuring node fault detection························································································································· 82
Configuring the optimal bypass tunnel selection interval·················································································· 82
Displaying and maintaining MPLS TE ·························································································································· 83
MPLS TE configuration examples·································································································································· 84
Establishing an MPLS TE tunnel over a static CRLSP·························································································· 84
Establishing an MPLS TE tunnel with RSVP-TE ···································································································· 88
Establishing an inter-AS MPLS TE tunnel with RSVP-TE ······················································································ 94
Bidirectional MPLS TE tunnel configuration example·······················································································102
CRLSP backup configuration example ··············································································································108
Manual bypass tunnel for FRR configuration example····················································································112
Auto FRR configuration example ·······················································································································117
IETF DS-TE configuration example ·····················································································································124
Troubleshooting MPLS TE ············································································································································131
No TE LSA generated ·········································································································································131
Configuring a static CRLSP····································································································································· 132
Overview·······································································································································································132
Configuration procedure·············································································································································132
Displaying static CRLSPs··············································································································································133
Static CRLSP configuration example ··························································································································133
Network requirements·········································································································································133
Configuration procedure ····································································································································134
Verifying the configuration·································································································································136
Configuring RSVP···················································································································································· 139
Overview·······································································································································································139
RSVP messages····················································································································································139
CRLSP setup procedure ·······································································································································140
RSVP refresh mechanism·····································································································································140
RSVP authentication ············································································································································141
RSVP GR·······························································································································································141
Protocols and standards ·····································································································································142
RSVP configuration task list·········································································································································142
Enabling RSVP······························································································································································142
Configuring RSVP refresh ············································································································································143
Configuring RSVP Srefresh and reliable RSVP message delivery ···········································································143
Configuring RSVP hello extension ······························································································································144
Configuring RSVP authentication································································································································144
Specifying a DSCP value for outgoing RSVP packets ······························································································146
Configuring RSVP GR ··················································································································································146
Enabling BFD for RSVP ················································································································································147
Displaying and maintaining RSVP······························································································································147
RSVP configuration examples ·····································································································································148
Establishing an MPLS TE tunnel with RSVP-TE ··································································································148
RSVP GR configuration example ·······················································································································152
Configuring tunnel policies····································································································································· 155
Overview·······································································································································································155
Configuring a tunnel policy ········································································································································155
Configuration guidelines ····································································································································155
Configuration procedure ····································································································································156
Displaying tunnel information ·····································································································································157
Tunnel policy configuration examples ·······················································································································157
Preferred tunnel configuration example ············································································································157
Exclusive tunnel configuration example ············································································································157

iv
Tunnel selection order configuration example ·································································································158
Preferred tunnel and tunnel selection order configuration example ······························································158
Configuring MPLS L3VPN······································································································································· 161
Overview·······································································································································································161
Basic MPLS L3VPN architecture·························································································································161
MPLS L3VPN concepts ········································································································································162
MPLS L3VPN route advertisement······················································································································163
MPLS L3VPN packet forwarding························································································································164
MPLS L3VPN networking schemes·····················································································································165
Inter-AS VPN ························································································································································167
Carrier's carrier ···················································································································································171
Nested VPN ·························································································································································173
HoVPN··································································································································································174
OSPF VPN extension···········································································································································176
BGP AS number substitution·······························································································································179
MPLS L3VPN FRR·················································································································································179
Protocols and standards ·····································································································································181
MPLS L3VPN configuration task list····························································································································181
Configuring basic MPLS L3VPN ·································································································································182
Configuration prerequisites ································································································································182
Configuring VPN instances ································································································································182
Configuring routing between a PE and a CE···································································································184
Configuring routing between PEs ······················································································································189
Configuring BGP VPNv4 route control ·············································································································190
Configuring inter-AS VPN ···········································································································································192
Configuring inter-AS option A····························································································································192
Configuring inter-AS option B ····························································································································192
Configuring inter-AS option C····························································································································193
Configuring nested VPN··············································································································································197
Configuring HoVPN·····················································································································································198
Configuring an OSPF sham link ·································································································································199
Configuring a loopback interface ·····················································································································199
Redistributing the loopback interface route ······································································································200
Creating a sham link···········································································································································200
Specifying the VPN label processing mode on the egress PE·················································································201
Configuring BGP AS number substitution··················································································································201
Configuring MPLS L3VPN FRR····································································································································201
Enabling logging for BGP route flapping··················································································································204
Enabling SNMP notifications for MPLS L3VPN·········································································································204
Displaying and maintaining MPLS L3VPN ················································································································204
MPLS L3VPN configuration examples························································································································206
Configuring basic MPLS L3VPN ························································································································206
Configuring a hub-spoke network ·····················································································································211
Configuring MPLS L3VPN inter-AS option A ····································································································218
Configuring MPLS L3VPN inter-AS option B·····································································································223
Configuring MPLS L3VPN inter-AS option C ····································································································228
Configuring MPLS L3VPN carrier's carrier ·······································································································235
Configuring nested VPN·····································································································································243
Configuring HoVPN ············································································································································252
Configuring an OSPF sham link ························································································································259
Configuring BGP AS number substitution ·········································································································264
Configuring MPLS L3VPN FRR through VPNv4 route backup for a VPNv4 route········································268
Configuring MPLS L3VPN FRR through VPNv4 route backup for an IPv4 route···········································270
Configuring MPLS L3VPN FRR through IPv4 route backup for a VPNv4 route·············································272

v
Configuring IPv6 MPLS L3VPN ······························································································································ 275
Overview·······································································································································································275
IPv6 MPLS L3VPN packet forwarding ···············································································································275
IPv6 MPLS L3VPN routing information advertisement ·····················································································276
IPv6 MPLS L3VPN network schemes and features ···························································································276
Protocols and standards ·····································································································································277
IPv6 MPLS L3VPN configuration task list ···················································································································277
Configuring basic IPv6 MPLS L3VPN·························································································································277
Configuration prerequisites ································································································································277
Configuring VPN instances ································································································································278
Configuring routing between a PE and a CE···································································································280
Configuring routing between PEs ······················································································································286
Configuring BGP VPNv6 route control ·············································································································286
Configuring inter-AS IPv6 VPN···································································································································288
Configuring inter-AS IPv6 VPN option A ··········································································································288
Configuring inter-AS IPv6 VPN option C ··········································································································288
Configuring an OSPFv3 sham link·····························································································································290
Configuring a loopback interface ·····················································································································290
Redistributing the loopback interface address ·································································································290
Creating a sham link···········································································································································290
Enabling logging for BGP routing flapping ··············································································································291
Displaying and maintaining IPv6 MPLS L3VPN········································································································291
IPv6 MPLS L3VPN configuration examples ···············································································································292
Configuring IPv6 MPLS L3VPNs·························································································································292
Configuring IPv6 MPLS L3VPN inter-AS option A····························································································299
Configuring IPv6 MPLS L3VPN inter-AS option C····························································································304
Configuring IPv6 MPLS L3VPN carrier's carrier·······························································································310
Configuring an OSPFv3 sham link ····················································································································317
Configuring MPLS L2VPN······································································································································· 323
Overview·······································································································································································323
Basic concepts of MPLS L2VPN ·························································································································323
MPLS L2VPN network models ····························································································································324
PW redundancy···················································································································································325
Multi-segment PW················································································································································326
VCCV····································································································································································328
MPLS L2VPN configuration task list····························································································································328
Enabling L2VPN ···························································································································································329
Configuring an AC ······················································································································································329
Configuring a cross-connect ·······································································································································330
Configuring a PW························································································································································331
Configuring a PW class······································································································································331
Configuring a static PW ·····································································································································331
Configuring an LDP PW······································································································································331
Configuring a BGP PW ······································································································································332
Configuring a remote CCC connection ············································································································334
Binding an AC to a cross-connect······························································································································335
Configuring PW redundancy······································································································································335
Configuring static PW redundancy ···················································································································336
Configuring LDP PW redundancy······················································································································336
Enabling MAC address software learning on an interface·····················································································337
Displaying and maintaining MPLS L2VPN ················································································································338
MPLS L2VPN configuration examples························································································································339
Configuring a static PW ·····································································································································339
Configuring an LDP PW······································································································································343

vi
Configuring a BGP PW ······································································································································347
Configuring a remote CCC connection ············································································································351
Configuring LDP PW redundancy······················································································································354
Configuring an intra-domain multi-segment PW ······························································································360
Configuring an inter-domain multi-segment PW ······························································································364
Configuring VPLS ···················································································································································· 371
Overview·······································································································································································371
Basic VPLS architecture·······································································································································371
VPLS implementation···········································································································································372
H-VPLS···································································································································································374
VPLS configuration task list··········································································································································376
Enabling L2VPN ···························································································································································377
Configuring an AC ······················································································································································377
Configuring a VSI ························································································································································378
Configuring a PW························································································································································379
Configuring a PW class······································································································································379
Configuring a static PW ·····································································································································379
Configuring an LDP PW······································································································································379
Configuring a BGP PW ······································································································································380
Configuring a BGP auto-discovery LDP PW ·····································································································382
Binding an AC to a VSI···············································································································································384
Configuring UPE dual homing ····································································································································385
Configuring static PW redundancy ···················································································································385
Configuring LDP PW redundancy······················································································································386
Configuring MAC address learning···························································································································386
Enabling packet statistics for an Ethernet service instance······················································································387
Displaying and maintaining VPLS ······························································································································387
VPLS configuration examples······································································································································388
Static PW configuration example ······················································································································388
LDP PW configuration example ·························································································································393
BGP PW configuration example························································································································395
BGP auto-discovery LDP PW configuration example·······················································································400
H-VPLS using access configuration example ····································································································404
H-VPLS UPE dual homing configuration example ····························································································409
Configuring MPLS OAM········································································································································· 415
Overview·······································································································································································415
MPLS ping ····························································································································································415
MPLS tracert ·························································································································································415
BFD for MPLS ·······················································································································································415
Periodic MPLS tracert ··········································································································································416
Protocols and standards ··············································································································································416
Configuring MPLS OAM for LSP tunnels····················································································································416
Configuring MPLS ping for LSPs ························································································································417
Configuring MPLS tracert for LSPs ·····················································································································417
Configuring BFD for LSPs····································································································································417
Configuring periodic MPLS tracert for LSPs······································································································418
Configuring MPLS OAM for MPLS TE tunnels ···········································································································418
Configuring MPLS OAM for a PW·····························································································································419
Configuring MPLS ping for a PW······················································································································419
Configuring BFD for a PW ·································································································································420
Displaying MPLS OAM················································································································································423
MPLS OAM configuration examples··························································································································423
BFD for LSP configuration example ···················································································································423

vii
BFD for PW configuration example···················································································································426
Configuring MCE ···················································································································································· 432
MPLS L3VPN overview ················································································································································432
Basic MPLS L3VPN architecture·························································································································432
MPLS L3VPN concepts ········································································································································433
MCE overview ······························································································································································434
MCE configuration task list ·········································································································································435
Configuring VPN instances ·········································································································································436
Creating a VPN instance····································································································································436
Associating a VPN instance with an interface ·································································································436
Configuring route related attributes for a VPN instance·················································································437
Configuring routing on an MCE·································································································································438
Configuring routing between an MCE and a VPN site···················································································438
Configuring routing between an MCE and a PE ·····························································································444
Displaying and maintaining MCE······························································································································448
MCE configuration examples ·····································································································································448
Configuring the MCE that uses OSPF to advertise VPN routes to the PE······················································448
Configuring the MCE that uses EBGP to advertise VPN routes to the PE······················································454
Configuring IPv6 MCE············································································································································ 458
Overview·······································································································································································458
IPv6 MCE configuration task list·································································································································458
Configuring VPN instances ·········································································································································458
Creating a VPN instance····································································································································458
Associating a VPN instance with an interface ·································································································459
Configuring route related attributes for a VPN instance·················································································459
Configuring routing on an MCE·································································································································461
Configuring routing between an MCE and a VPN site···················································································461
Configuring routing between an MCE and a PE ·····························································································466
Displaying and maintaining IPv6 MCE······················································································································469
IPv6 MCE configuration example·······························································································································470
Support and other resources ·································································································································· 477
Contacting HP ······························································································································································477
Subscription service ············································································································································477
Related information······················································································································································477
Documents····························································································································································477
Websites·······························································································································································477
Conventions ··································································································································································478
Index ········································································································································································ 480

1
Configuring basic MPLS
Multiprotocol Label Switching (MPLS) provides connection-oriented label switching over connectionless IP
backbone networks. It integrates both the flexibility of IP routing and the simplicity of Layer 2 switching.
In this chapter, the term "interface" refers to a Layer 3 interface. It can be a VLAN interface or a Layer 3
Ethernet interface. Layer 3 Ethernet interfaces refer to the Ethernet interfaces that operate in Layer 3 mode.
For information about switching the Ethernet interface operating mode, see Layer 2—LAN Switching
Configuration Guide.
Overview
MPLS has the following advantages:
•High speed and efficiency—MPLS uses short- and fixed-length labels to forward packets, avoiding
complicated routing table lookups.
•Multiprotocol support—MPLS resides between the link layer and the network layer. It can work over
various link layer protocols (for example, PPP, ATM, frame relay, and Ethernet) to provide
connection-oriented services for various network layer protocols (for example, IPv4, IPv6, and IPX).
•Good scalability—The connection-oriented switching and multilayer label stack features enable
MPLS to deliver various extended services, such as VPN, traffic engineering, and QoS.
Basic concepts
FEC
MPLS groups packets with the same characteristics (such as packets with the same destination or service
class) into a forwarding equivalence class (FEC). Packets of the same FEC are handled in the same way
on an MPLS network.
Label
A label uniquely identifies an FEC and has local significance.
Figure 1 Format of a label
A label is encapsulated between the Layer 2 header and Layer 3 header of a packet. It is four bytes long
and consists of the following fields:
•Label—20-bit label value.
•TC—3-bit traffic class, used for QoS. It is also called Exp.

2
•S—1-bit bottom of stack flag. A label stack can have multiple labels. The label nearest to the Layer
2 header is called the top label, and the label nearest to the Layer 3 header is called the bottom
label. The Sfield is set to 1 if the label is the bottom label and set to 0 if not.
•TTL—8-bit time to live field used for routing loop prevention.
LSR
A router that performs MPLS forwarding is a label switching router (LSR).
LSP
A label switched path (LSP) is the path along which packets of an FEC travel through an MPLS network.
An LSP is a unidirectional packet forwarding path. Two neighboring LSRs are called the upstream LSR
and downstream LSR along the direction of an LSP. In Figure 2,LSR B is the downstream LSR of LSR A, and
LSR A is the upstream LSR of LSR B.
Figure 2 Label switched path
LFIB
The Label Forwarding Information Base (LFIB) on an MPLS network functions like the Forwarding
Information Base (FIB) on an IP network. When an LSR receives a labeled packet, it searches the LFIB to
obtain information for forwarding the packet, such as the label operation type, the outgoing label value,
and the next hop.
Control plane and forwarding plane
An MPLS node consists of a control plane and a forwarding plane.
•Control plane—Assigns labels, distributes FEC-label mappings to neighbor LSRs, creates the LFIB,
and establishes and removes LSPs.
•Forwarding plane—Forwards packets according to the LFIB.

3
MPLS network architecture
Figure 3 MPLS network architecture
An MPLS network has the following types of LSRs:
•Ingress LSR—Ingress LSR of packets. It labels packets entering into the MPLS network.
•Transit LSR—Intermediate LSRs in the MPLS network. The transit LSRs on an LSP forward packets to
the egress LSR according to labels.
•Egress LSR—Egress LSR of packets. It removes labels from packets and forwards the packets to their
destination networks.
LSP establishment
LSPs include static and dynamic LSPs.
•Static LSP—To establish a static LSP, you must configure an LFIB entry on each LSR along the LSP.
Establishing static LSPs consumes fewer resources than establishing dynamic LSPs, but static LSPs
cannot automatically adapt to network topology changes. Therefore, static LSPs are suitable for
small-scale networks with simple, stable topologies.
•Dynamic LSP—Established by a label distribution protocol (also called an MPLS signaling protocol).
A label distribution protocol classifies FECs, distributes FEC-label mappings, and establishes and
maintains LSPs. Label distribution protocols include protocols designed specifically for label
distribution, such as the Label Distribution Protocol (LDP), and protocols extended to support label
distribution, such as MP-BGP and RSVP-TE.
In this document, the term "label distribution protocols" refers to all protocols for label distribution. The
term "LDP" refers to the RFC 5036 LDP.
A dynamic LSP is established in the following steps:
1. A downstream LSR classifies FECs according to destination addresses.
2. The downstream LSR assigns a label for each FEC, and distributes the FEC-label binding to its
upstream LSR.
3. The upstream LSR establishes an LFIB entry for the FEC according to the binding information.
After all LSRs along the LSP establish an LFIB entry for the FEC, a dynamic LSP is established for the
packets of this FEC.

4
Figure 4 Dynamic LSP establishment
MPLS forwarding
Figure 5 MPLS forwarding
As shown in Figure 5, a packet is forwarded over the MPLS network in the following steps:
1. Router B (the ingress LSR) receives a packet with no label. It then does the following:
a. Identifies the FIB entry that matches the destination address of the packet.
b. Adds the outgoing label (40, in this example) to the packet.
c. Forwards the labeled packet out of the interface VLAN-interface 20 to the next hop LSR Router
C.
2. When receiving the labeled packet, Router C processes the packet as follows:
a. Identifies the LFIB entry that has an incoming label of 40.
b. Uses the outgoing label 50 of the entry to replace label 40 in the packet.

5
c. Forwards the labeled packet out of the outgoing interface VLAN-interface 30 to the next hop
LSR Router D.
3. When receiving the labeled packet, Router D (the egress) processes the packet as follows:
a. Identifies the LFIB entry that has an incoming label of 50.
b. Removes the label from the packet.
c. Forwards the packet out of the outgoing interface VLAN-interface 40 to the next hop LSR Router
E.
If the LFIB entry records no outgoing interface or next hop information, Router D does the following:
a. Identifies the FIB entry by the IP header.
b. Forwards the packet according to the FIB entry.
PHP
An egress node must perform two forwarding table lookups to forward a packet:
•Two LFIB lookups (if the packet has more than one label).
•One LFIB lookup and one FIB lookup (if the packet has only one label).
The penultimate hop popping (PHP) feature can pop the label at the penultimate node, so the egress
node only performs one table lookup.
A PHP-capable egress node sends the penultimate node an implicit null label of 3. This label never
appears in the label stack of packets. If an incoming packet matches an LFIB entry comprising the implicit
null label, the penultimate node pops the top label of the packet and forwards the packet to the egress
LSR. The egress LSR directly forwards the packet.
Sometimes, the egress node must use the TC field in the label to perform QoS. To keep the TC information,
you can configure the egress node to send the penultimate node an explicit null label of 0. If an incoming
packet matches an LFIB entry comprising the explicit null label, the penultimate hop replaces the value of
the top label with value 0, and forwards the packet to the egress node. The egress node gets the TC
information, pops the label of the packet, and forwards the packet.
Protocols and standards
•RFC 3031, Multiprotocol Label Switching Architecture
•RFC 3032, MPLS Label Stack Encoding
•RFC 5462, Multiprotocol Label Switching (MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic
Class" Field
MPLS configuration task list
Tasks at a
g
lance
(Required.) Enabling MPLS
(Optional.) Configuring MPLS MTU
(Optional.) Specifying the label type advertised by the egress
(Optional.) Configuring TTL propagation

6
Tasks at a
g
lance
(Optional.) Enabling sending of MPLS TTL-expired messages
(Optional.) Enabling MPLS forwarding statistics
(Optional.) Enabling SNMP notifications for MPLS
Enabling MPLS
Before you enable MPLS, perform the following tasks:
•Configure link layer protocols to ensure connectivity at the link layer.
•Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
•Configure static routes or an IGP protocol to ensure IP connectivity among LSRs.
To enable MPLS:
Ste
p
Command Remarks
1. Enter system view. system-view N/A
2. Configure an LSR ID for the local
node. mpls lsr-id lsr-id
By default, no LSR ID is configured.
An LSR ID must be unique in an MPLS
network and in IP address format. HP
recommends that you use the IP
address of a loopback interface as
an LSR ID.
3. Enter the view of the interface
that needs to perform MPLS
forwarding.
interface interface-type
interface-number N/A
4. Enable MPLS for the interface. mpls enable By default, MPLS is disabled on an
interface.
Configuring MPLS MTU
MPLS inserts the label stack between the link layer header and network layer header of each packet. To
make sure the size of MPLS labeled packets is smaller than the MTU of an interface, configure an MPLS
MTU on the interface.
MPLS compares each MPLS packet against the interface MPLS MTU. When the packet exceeds the MPLS
MTU:
•If fragmentation is allowed, MPLS does the following:
a. Removes the label stack from the packet.
b. Fragments the IP packet. The length of a fragment is the MPLS MTU minus the length of the label
stack.
c. Adds the label stack to each fragment, and forwards the fragments.
•If fragmentation is not allowed, the LSR drops the packet.
To configure an MPLS MTU for an interface:

7
Ste
p
Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view. interface interface-type
interface-number N/A
3. Configure an MPLS MTU for
the interface. mpls mtu value By default, no MPLS MTU is
configured on an interface.
The following applies when an interface handles MPLS packets:
•MPLS packets carrying L2VPN or IPv6 packets are always forwarded by an interface, even if the
length of the MPLS packets exceeds the MPLS MTU of the interface. Whether the forwarding can
succeed depends on the actual forwarding capacity of the interface.
•If the MPLS MTU of an interface is greater than the MTU of the interface, data forwarding might fail
on the interface.
•If you do not configure the MPLS MTU of an interface, fragmentation of MPLS packets is based on
the MTU of the interface without considering MPLS labels. An MPLS fragment might be larger than
the interface MTU and be dropped.
Specifying the label type advertised by the egress
In an MPLS network, an egress can advertise the following types of labels:
•Implicit null label with a value of 3.
•Explicit null label with a value of 0.
•Non-null label. The value range for a non-null label is 16 to 1048575.
For LSPs established by a label distribution protocol, the label advertised by the egress determines how
the penultimate hop processes a labeled packet.
•If the egress advertises an implicit null label, the penultimate hop directly pops the top label of a
matching packet.
•If the egress advertises an explicit null label, the penultimate hop swaps the top label value of a
matching packet with the explicit null label.
•If the egress advertises a non-null label (normal label), the penultimate hop swaps the top label of
a matching packet with the specific label assigned by the egress.
Configuration guidelines
If the penultimate hop supports PHP, HP recommends that you configure the egress to advertise an
implicit null label to the penultimate hop. If you want to simplify packet forwarding on the egress but keep
labels to determine QoS policies, configure the egress to advertise an explicit null label to the
penultimate hop. HP recommends using non-null labels only in particular scenarios. For example, when
OAM is configured on the egress, the egress can get the OAM function entity status only through non-null
labels.
As a penultimate hop, the device accepts the implicit null label, explicit null label, or normal label
advertised by the egress device.
For LDP LSPs, the mpls label advertise command triggers LDP to delete the LSPs established before the
command is executed and re-establishes new LSPs.

8
For BGP LSPs, the mpls label advertise command takes effect only for the BGP LSPs established after the
command is executed. To apply the new setting to BGP LSPs established before the command is executed,
delete the routes corresponding to the BGP LSPs, and then redistribute the routes.
Configuration procedure
To specify the type of label that the egress node will advertise to the penultimate hop:
Ste
p
Command Remarks
1. Enter system view. system-view N/A
2. Specify the label type
advertised by the egress to the
penultimate hop.
mpls label advertise { explicit-null
| implicit-null | non-null }
By default, an egress advertises an
implicit null label to the penultimate
hop.
Configuring TTL propagation
When TTL propagation is enabled, the ingress node copies the TTL value of an IP packet to the TTL field
of the label. Each LSR on the LSP decreases the label TTL value by 1. The LSR that pops the label copies
the remaining label TTL value back to the IP TTL of the packet, so the IP TTL value can reflect how many
hops the packet has traversed in the MPLS network. The IP tracert facility can show the real path along
which the packet has traveled.
Figure 6 TTL propagation
When TTL propagation is disabled, the ingress node sets the label TTL to 255. Each LSR on the LSP
decreases the label TTL value by 1. The LSR that pops the label does not change the IP TTL value when
popping the label. Therefore, the MPLS backbone nodes are invisible to user networks, and the IP tracert
facility cannot show the real path in the MPLS network.

9
Figure 7 Without TTL propagation
Follow these guidelines when you configure TTL propagation:
•HP recommends setting the same TTL processing mode on all LSRs of an LSP.
•To enable TTL propagation for a VPN, you must enable it on all PE devices in the VPN, so that you
can get the same traceroute result (hop count) from those PEs.
To enable TTL propagation:
Ste
p
Command Remarks
1. Enter system view. system-view N/A
2. Enable TTL propagation. mpls ttl propagate { public |
vpn }
By default, TTL propagation is enabled only
for public-network packets.
This command affects only the propagation
between IP TTL and label TTL. Within an
MPLS network, TTL is always copied between
the labels of an MPLS packet.
After TTL propagation is enabled or disabled, execute the reset mpls ldp command to make the
configuration take effect. For more information about the reset mpls ldp command, see MPLS Command
Reference.
Enabling sending of MPLS TTL-expired messages
This feature enables an LSR to generate an ICMP TTL-expired message upon receiving an MPLS packet
with a TTL of 1. If the MPLS packet has only one label, the LSR sends the ICMP TTL-expired message back
to the source through IP routing. If the MPLS packet has multiple labels, the LSR sends it along the LSP to
the egress, which then sends the message back to the source.
To enable sending of MPLS TTL-expired messages:
Ste
p
Command Remarks
1. Enter system view. system-view N/A
2. Enable sending of MPLS
TTL-expired messages. mpls ttl expiration enable By default, this function is enabled.

10
Enabling MPLS forwarding statistics
MPLS label forwarding forwards a labeled packet based on its incoming label.
Perform this task to enable MPLS label forwarding statistics and MPLS statistics reading, so that you can
use the display mpls lsp verbose command to view MPLS label statistics.
To enable MPLS label forwarding statistics:
Ste
p
Command Remarks
1. Enter system view. system-view N/A
2. Enable MPLS label
forwarding statistics for
specific LSPs.
mpls statistics { all | [ vpn-instance
vpn-instance-name ] { ipv4
ipv4-destination mask-length | ipv6
ipv6-destination prefix-length } | static
| te ingress-lsr-id tunnel-id }
By default, MPLS label forwarding
statistics are disabled for all LSPs.
3. Enable MPLS label
statistics reading, and
specify the reading
interval.
mpls statistics interval interval By default, MPLS label statistics
reading is disabled.
Enabling SNMP notifications for MPLS
This feature enables MPLS to generate SNMP notifications. The generated SNMP notifications are sent to
the SNMP module.
For more information about SNMP notifications, see Network Management and Monitoring
Configuration Guide.
To enable SNMP notifications for MPLS:
Ste
p
Command Remarks
1. Enter system view. system-view N/A
2. Enable SNMP notifications
for MPLS. snmp-agent trap enable mpls By default, SNMP notifications for
MPLS are enabled.
Displaying and maintaining MPLS
Execute display commands in any view and reset commands in user view.
Task Command
Display MPLS interface information. display mpls interface [ interface-type interface-number ]
Display usage information about MPLS
labels. display mpls label { label-value1 [ to label-value2 ] | all }

11
Task Command
Display LSP information.
display mpls lsp [ egress | in-label label-value | ingress |
outgoing-interface interface-type interface-number | protocol { bgp
| ldp | local | rsvp-te | static | static-cr } | transit ] [ vpn-instance
vpn-instance-name ] [ ipv4-dest mask-length | ipv6 [ ipv6-dest
prefix-length ] ] [ verbose ]
Display MPLS Nexthop Information Base
(NIB) information. display mpls nib [ nib-id ]
Display usage information about NIDs. display mpls nid [ nid-value1 [ to nid-value2 ] ]
Display LSP statistics. display mpls lsp statistics
Display MPLS summary information. display mpls summary
Display ILM entries. display mpls forwarding ilm [ label ] [ slot slot-number ]
Display NHLFE entries. display mpls forwarding nhlfe [ nid ] [ slot slot-number ]
Clear MPLS forwarding statistics for the
specified LSPs.
reset mpls statistics { all | [ vpn-instance vpn-instance-name ] { ipv4
ipv4-destination mask-length | ipv6 ipv6-destination prefix-length }
| static | te ingress-lsr-id tunnel-id }