The configuration examples in this document were created and verified in a lab environment, and all the devices were started with the factory default configuration. When you are working on a live network, make sure you understand the potential impact of every command on your network.

This document assumes that you have basic knowledge of MPLS OAM.

Example: Configuring BFD for an LSP

Network configuration

As shown in Figure 1, Branch 1 and Branch 2 of a company are connected to each other through an MPLS backbone of the ISP. The branches need to exchange real-time data.

To ensure high availability of the real-time service between the branches, deploy LDP FRR on the MPLS backbone to provide a primary LSP and a backup LSP. Configure BFD for the primary LSP, so when the primary LSP fails, BFD can quickly detect the failure and notify LDP of the failure to trigger a traffic switchover to the backup LSP.

Figure 1 Network diagram

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Procedures

1. Assign IP addresses to interfaces:

# Assign an IP address to Ten-GigabitEthernet 3/1/1 on PE 1.

<PE1> system-view

[PE1] interface Ten-GigabitEthernet3/1/1

[PE1-Ten-GigabitEthernet3/1/1] ip address 12.12.12.1 24

[PE1-Ten-GigabitEthernet3/1/1] quit

# Assign IP addresses to other interfaces (including the loopback interfaces) according to Figure 1. (Details not shown.)

2. On the MPLS backbone, configure OSPF to ensure IP connectivity between the routers, and enable OSPF FRR.

# Configure PE 1.

[PE1] ospf

[PE1-ospf-1] area 0

[PE1-ospf-1-area-0.0.0.0] network 1.1.1.1 0.0.0.0

[PE1-ospf-1-area-0.0.0.0] network 12.12.12.0 0.0.0.255

[PE1-ospf-1-area-0.0.0.0] network 14.14.14.0 0.0.0.255

[PE1-ospf-1-area-0.0.0.0] network 192.168.10.0 0.0.0.255

[PE1-ospf-1-area-0.0.0.0] quit

[PE1-ospf-1] fast-reroute lfa

[PE1-ospf-1] quit

# Configure P.

[P1] ospf

[P1-ospf-1] area 0

[P1-ospf-1-area-0.0.0.0] network 2.2.2.2 0.0.0.0

[P1-ospf-1-area-0.0.0.0] network 12.12.12.0 0.0.0.255

[P1-ospf-1-area-0.0.0.0] network 23.23.23.0 0.0.0.255

[P1-ospf-1-area-0.0.0.0] quit

[P1-ospf-1] quit

# Configure PE 2.

[PE2] ospf

[PE2-ospf-1] area 0

[PE2-ospf-1-area-0.0.0.0] network 3.3.3.3 0.0.0.0

[PE2-ospf-1-area-0.0.0.0] network 23.23.23.0 0.0.0.255

[PE2-ospf-1-area-0.0.0.0] network 34.34.34..0 0.0.0.255

[PE2-ospf-1-area-0.0.0.0] network 192.168.20.0 0.0.0.255

[PE2-ospf-1-area-0.0.0.0] quit

[PE2-ospf-1] fast-reroute lfa

[PE2-ospf-1] quit

# Configure P 2.

[P2] ospf

[P2-ospf-1] area 0

[P2-ospf-1-area-0.0.0.0] network 4.4.4.4 0.0.0.0

[P2-ospf-1-area-0.0.0.0] network 14.14.14.0 0.0.0.255

[P2-ospf-1-area-0.0.0.0] network 34.34.34.0 0.0.0.255

[P2-ospf-1-area-0.0.0.0] quit

[P2-ospf-1] quit

# Adjust the OSPF cost values of Ten-GigabitEthernet 3/1/1 and Ten-GigabitEthernet 3/1/2 to ensure that the OSPF cost of the backup LSP is greater than that of the primary LSP.

[P2] interface Ten-GigabitEthernet3/1/1

[P2-Ten-GigabitEthernet3/1/1] ospf cost 10

[P2-Ten-GigabitEthernet3/1/1] quit

[P2] interface Ten-GigabitEthernet3/1/2

[P2-Ten-GigabitEthernet3/1/2] ospf cost 10

[P2-Ten-GigabitEthernet3/1/2] quit

3. Configure basic MPLS and enable LDP.

# Configure PE 1.

[PE1] mpls lsr-id 1.1.1.1

[PE1] mpls ldp

[PE1-ldp] quit

[PE1] interface Ten-GigabitEthernet3/1/1

[PE1-Ten-GigabitEthernet3/1/1] mpls enable

[PE1-Ten-GigabitEthernet3/1/1] mpls ldp enable

[PE1-Ten-GigabitEthernet3/1/1] quit

[PE1] interface Ten-GigabitEthernet3/1/2

[PE1-Ten-GigabitEthernet3/1/2] mpls enable

[PE1-Ten-GigabitEthernet3/1/2] mpls ldp enable

[PE1-Ten-GigabitEthernet3/1/2] quit

# Configure P 1.

[P1] mpls lsr-id 2.2.2.2

[P1] mpls ldp

[P1-ldp] quit

[P1] interface Ten-GigabitEthernet3/1/1

[P1-Ten-GigabitEthernet3/1/1] mpls enable

[P1-Ten-GigabitEthernet3/1/1] mpls ldp enable

[P1-Ten-GigabitEthernet3/1/1] quit

[P1] interface Ten-GigabitEthernet3/1/2

[P1-Ten-GigabitEthernet3/1/2] mpls enable

[P1-Ten-GigabitEthernet3/1/2] mpls ldp enable

[P1-Ten-GigabitEthernet3/1/2] quit

# Configure PE 2.

[PE2] mpls lsr-id 3.3.3.3

[PE2] mpls ldp

[PE2-ldp] quit

[PE2] interface Ten-GigabitEthernet3/1/1

[PE2-Ten-GigabitEthernet3/1/1] mpls enable

[PE2-Ten-GigabitEthernet3/1/1] mpls ldp enable

[PE2-Ten-GigabitEthernet3/1/1] quit

[PE2] interface Ten-GigabitEthernet3/1/2

[PE2-Ten-GigabitEthernet3/1/2] mpls enable

[PE2-Ten-GigabitEthernet3/1/2] mpls ldp enable

[PE2-Ten-GigabitEthernet3/1/2] quit

# Configure P 2.

[P2] mpls lsr-id 4.4.4.4

[P2] mpls ldp

[P2-ldp] quit

[P2] interface Ten-GigabitEthernet3/1/1

[P2-Ten-GigabitEthernet3/1/1] mpls enable

[P2-Ten-GigabitEthernet3/1/1] mpls ldp enable

[P2-Ten-GigabitEthernet3/1/1] quit

[P2] interface Ten-GigabitEthernet3/1/2

[P2-Ten-GigabitEthernet3/1/2] mpls enable

[P2-Ten-GigabitEthernet3/1/2] mpls ldp enable

[P2-Ten-GigabitEthernet3/1/2] quit

After the previous configuration, you can see that the state of LDP sessions is Operational. Take PE 1 as an example:

[PE1] display mpls ldp peer

Total number of peers: 2

Peer LDP ID State Role GR MD5 KA Sent/Rcvd

2.2.2.2:0 Operational Passive Off Off 55/55

4.4.4.4:0 Operational Passive Off Off 6/6

4. Configure an LSP generation policy to establish LSPs for routes destined for 192.168.10.0/24, 192.168.20.0/24, 1.1.1.1/32, and 3.3.3.3/32:

# On PE 1, create an IP prefix list named PE1. Configure that only the routes permitted by the prefix can trigger LDP to establish LSPs.

[PE1] ip prefix-list PE1 index 10 permit 192.168.10.0 24

[PE1] ip prefix-list PE1 index 20 permit 192.168.20.0 24

[PE1] ip prefix-list PE1 index 30 permit 1.1.1.1 32

[PE1] ip prefix-list PE1 index 40 permit 3.3.3.3 32

[PE1] mpls ldp

[PE1-ldp] lsp-trigger prefix-list PE1

[PE1-ldp] quit

# On P 1, create an IP prefix list named P1. Configure that only the routes permitted by the prefix can trigger LDP to establish LSPs.

[P1] ip prefix-list P1 index 10 permit 192.168.10.0 24

[P1] ip prefix-list P1 index 20 permit 192.168.20.0 24

[P1] ip prefix-list P1 index 30 permit 1.1.1.1 32

[P1] ip prefix-list P1 index 40 permit 3.3.3.3 32

[P1] mpls ldp

[P1-ldp] lsp-trigger prefix-list P1

[P1-ldp] quit

# On PE 2, create an IP prefix list named PE2. Configure that only the routes permitted by the prefix can trigger LDP to establish LSPs.

[PE2] ip prefix-list PE2 index 10 permit 192.168.10.0 24

[PE2] ip prefix-list PE2 index 20 permit 192.168.20.0 24

[PE2] ip prefix-list PE2 index 30 permit 1.1.1.1 32

[PE2] ip prefix-list PE2 index 40 permit 3.3.3.3 32

[PE2] mpls ldp

[PE2-ldp] lsp-trigger prefix-list PE2

[PE2-ldp] quit

# On P 2, create an IP prefix list named P2. Configure that only the routes permitted by the prefix can trigger LDP to establish LSPs.

[P2] ip prefix-list P2 index 10 permit 192.168.10.0 24

[P2] ip prefix-list P2 index 20 permit 192.168.20.0 24

[P2] ip prefix-list P2 index 30 permit 1.1.1.1 32

[P2] ip prefix-list P2 index 40 permit 3.3.3.3 32

[P2] mpls ldp

[P2-ldp] lsp-trigger prefix-list P2

[P2-ldp] quit

# Execute the display mpls ldp lsp command on PE 1. The output shows that the LSP destined for 192.168.20.0/24 has been established.

[PE1]display mpls ldp lsp

VPN instance: public instance

Status Flags: * - stale, L - liberal, B - backup, N/A – unavailable

FECs: 4 Ingress: 4 Transit: 4 Egress: 2

FEC In/Out Label Nexthop OutInterface/LSINDEX

1.1.1.1/32 3/-

-/1151(L)

-/1279(L)

3.3.3.3/32 -/1150 12.12.12.2 XGE3/1/1

1150/1150 12.12.12.2 XGE3/1/1

-/1150(B) 12.12.12.2 XGE3/1/2

1150/1150(B) 12.12.12.2 XGE3/1/2

192.168.10.0/24 1141/-

-/1141(L)

192.168.20.0/24 -/1133 12.12.12.2 XGE3/1/1

1133/1133 12.12.12.2 XGE3/1/1

-/1133(B) 14.14.14.4 XGE3/1/2

1133/1133(B) 14.14.14.4 XGE3/1/2

5. Enable BFD for MPLS, and configure BFD to verify connectivity for the LSP:

# Configure PE 1.

[PE1] mpls bfd enable

[PE1] mpls bfd 3.3.3.3 32

# Configure PE 2.

[PE2] mpls bfd enable

[PE2] mpls bfd 1.1.1.1 32

Verifying the configuration

1. On PE 1 and PE 2, execute the display mpls bfd command to view information about the BFD sessions for the LSPs. Take PE 1 as an example:

[PE1]display mpls bfd

Total number of sessions: 2, 2 up, 0 down, 0 init

FEC Type: LSP

FEC Info:

Destination: 1.1.1.1

Mask Length: 32

NHLFE ID: -

Local Discr: 1026 Remote Discr: 514

Source IP: 1.1.1.1 Destination IP: 3.3.3.3

Session State: Up Session Role: Active

Template Name: -

FEC Type: LSP

FEC Info:

Destination: 3.3.3.3

Mask Length: 32

NHLFE ID: 1028

Local Discr: 1025 Remote Discr: -

Source IP: 1.1.1.1 Destination IP: 127.0.0.1

Session State: Up Session Role: Passive

Template Name: -

2. On PE 1, execute the tracert mpls ipv4 command to verify that the current LSP in use is the primary LSP. (To use the tracert feature, you must also enable sending of ICMP time exceeded messages on the transit devices and enable sending of ICMP destination unreachable messages on the destination device.)

<PE1>tracert mpls -a 192.168.10.1 ipv4 192.168.20.0 24

MPLS trace route FEC 192.168.20.0/24

TTL Replier Time Type Downstream

0 Ingress 12.12.12.2/[1141]

1 12.12.12.2 2 ms Transit 23.23.23.3/[1141]

2 23.23.23.3 2 ms Egress

3. Continuously ping PE 2 from PE 1. During this period, shut down Ten-GigabitEthernet 3/1/1 of P 1. Verify the communication between PE 1 and PE 2.

# Continuously ping PE 2 from PE 1.

<PE1>ping -c 100000 -a 192.168.10.1 192.168.20.1

Ping 192.168.20.1 (192.168.20.1) from 192.168.10.1: 56 data bytes, press CTRL_C

to break

56 bytes from 192.168.20.1: icmp_seq=0 ttl=254 time=2.576 ms

56 bytes from 192.168.20.1: icmp_seq=1 ttl=254 time=1.996 ms

...

# Shut down Ten-GigabitEthernet 3/1/1 of P 1.

[P1] interface Ten-GigabitEthernet3/1/1

[P1-Ten-GigabitEthernet3/1/1] shut

# You can see that PE 1 and PE 2 resumed connectivity quickly after a short period of disconnection.

<PE1>ping -c 100000 -a 192.168.10.1 192.168.20.1

Ping 192.168.20.1 (192.168.20.1) from 192.168.10.1: 56 data bytes, press CTRL_C

to break

56 bytes from 192.168.20.1: icmp_seq=0 ttl=254 time=2.576 ms

56 bytes from 192.168.20.1: icmp_seq=1 ttl=254 time=1.996 ms

...

56 bytes from 192.168.20.1: icmp_seq=7 ttl=254 time=2.214 ms

Request time out

56 bytes from 192.168.20.1: icmp_seq=9 ttl=254 time=2.659 ms

56 bytes from 192.168.20.1: icmp_seq=10 ttl=254 time=5.049 ms

56 bytes from 192.168.20.1: icmp_seq=11 ttl=254 time=2.098 ms

56 bytes from 192.168.20.1: icmp_seq=12 ttl=254 time=2.225 ms

56 bytes from 192.168.20.1: icmp_seq=13 ttl=254 time=2.187 ms

--- Ping statistics for 192.168.20.1 ---

14 packet(s) transmitted, 13 packet(s) received, 7.1% packet loss

round-trip min/avg/max/std-dev = 1.990/2.455/5.049/0.772 ms

4. Test whether a switchover has happened:

# On PE 1, execute the tracert mpls ipv4 command. You can see the currently used LSP is the bakcup LSP.

<PE1>tracert mpls -a 192.168.10.1 ipv4 192.168.20.0 24

MPLS trace route FEC 192.168.20.0/24

TTL Replier Time Type Downstream

0 Ingress 14.14.14.4/[1133]

1 14.14.14.4 2 ms Transit 34.34.34.3/[1141]

2 34.34.34.3 2 ms Egress

Configuration files

· PE 1

ospf 1

fast-reroute lfa

area 0.0.0.0

network 1.1.1.1 0.0.0.0

network 12.12.12.0 0.0.0.255

network 14.14.14.0 0.0.0.255

network 192.168.10.0 0.0.0.255

mpls lsr-id 1.1.1.1

mpls ldp

lsp-trigger prefix-list PE1

mpls bfd enable

interface LoopBack0

ip address 1.1.1.1 255.255.255.255

interface Ten-GigabitEthernet3/1/1

port link-mode route

ip address 12.12.12.1 255.255.255.0

mpls enable

mpls ldp enable

interface Ten-GigabitEthernet3/1/2

port link-mode route

ip address 14.14.14.1 255.255.255.0

mpls enable

mpls ldp enable

ip prefix-list PE1 index 10 permit 192.168.10.0 24

ip prefix-list PE1 index 20 permit 192.168.20.0 24

ip prefix-list PE1 index 30 permit 1.1.1.1 32

ip prefix-list PE1 index 40 permit 3.3.3.3 32

mpls bfd 3.3.3.3 32

· PE 2

ospf 1

fast-reroute lfa

area 0.0.0.0

network 3.3.3.3 0.0.0.0

network 23.23.23.0 0.0.0.255

network 34.34.34.0 0.0.0.255

network 192.168.20.0 0.0.0.255

mpls lsr-id 3.3.3.3

mpls ldp

lsp-trigger prefix-list PE2

mpls bfd enable

interface LoopBack0

ip address 3.3.3.3 255.255.255.255

interface Ten-GigabitEthernet3/1/1

port link-mode route

ip address 34.34.34.3 255.255.255.0

mpls enable

mpls ldp enable

interface Ten-GigabitEthernet3/1/2

port link-mode route

ip address 23.23.23.3 255.255.255.0

mpls enable

mpls ldp enable

ip prefix-list PE2 index 10 permit 192.168.10.0 24

ip prefix-list PE2 index 20 permit 192.168.20.0 24

ip prefix-list PE2 index 30 permit 1.1.1.1 32

ip prefix-list PE2 index 40 permit 3.3.3.3 32

mpls bfd 1.1.1.1 32

· P 1

ospf 1

area 0.0.0.0

network 2.2.2.2 0.0.0.0

network 12.12.12.0 0.0.0.255

network 23.23.23.0 0.0.0.255

mpls lsr-id 2.2.2.2

mpls ldp

lsp-trigger prefix-list P1

interface LoopBack0

ip address 2.2.2.2 255.255.255.255

interface Ten-GigabitEthernet3/1/1

port link-mode route

ip address 12.12.12.2 255.255.255.0

mpls enable

mpls ldp enable

interface Ten-GigabitEthernet3/1/2

port link-mode route

ip address 23.23.23.2 255.255.255.0

mpls enable

mpls ldp enable

ip prefix-list P1 index 10 permit 192.168.10.0 24

ip prefix-list P1 index 20 permit 192.168.20.0 24

ip prefix-list P1 index 30 permit 1.1.1.1 32

ip prefix-list P1 index 40 permit 3.3.3.3 32

· P 2

ospf 1

area 0.0.0.0

network 4.4.4.4 0.0.0.0

network 14.14.14.0 0.0.0.255

network 34.34.34.0 0.0.0.255

mpls lsr-id 4.4.4.4

mpls ldp

lsp-trigger prefix-list P2

interface LoopBack0

ip address 4.4.4.4 255.255.255.255

interface Ten-GigabitEthernet3/1/1

port link-mode route

ip address 34.34.34.4 255.255.255.0

ospf cost 10

mpls enable

mpls ldp enable

interface Ten-GigabitEthernet3/1/2

port link-mode route

ip address 14.14.14.4 255.255.255.0

ospf cost 10

mpls enable

mpls ldp enable

ip prefix-list P2 index 10 permit 192.168.10.0 24

ip prefix-list P2 index 20 permit 192.168.20.0 24

ip prefix-list P2 index 30 permit 1.1.1.1 32

ip prefix-list P2 index 40 permit 3.3.3.3 32

Example: Configuring BFD for an MPLS TE tunnel

Network configuration

As shown in Figure 2, Branch 1 and Branch 2 of a company are connected to each other through an MPLS TE tunnel. The branches need to exchange real-time data.

To ensure high availability of the real-time service between the branches, deploy CRLSP backup for the MPLS TE tunnel to provide a primary CRLSP and a backup CRLSP. Configure BFD for the MPLS TE tunnel, so when the primary CRLSP fails, BFD can quickly detect the failure and notify RSVP of the failure to trigger a traffic switchover to the backup CRLSP.

Figure 2 Network diagram

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Restrictions and guidelines

· OSPF TE uses Opaque Type 10 LSAs to carry link TE attributes. To configure OSPF TE, you must enable the OSPF Opaque capability. For more information about the OSPF Opaque capability, see OSPF configuration in Layer 3—IP Routing Configuration Guide for the device.

· MPLS TE cannot reserve resources and allocate labels on OSPF virtual links to establish CRLSPs. To configure OSPF TE, make sure no virtual links exist in OSPF areas.

Procedures

1. Assign IP addresses to interfaces:

# Assign an IP address to Ten-GigabitEthernet 3/1/1 on Router A.

<RouterA> system-view

[RouterA] interface Ten-GigabitEthernet3/1/1

[RouterA-Ten-GigabitEthernet3/1/1] ip address 12.12.12.1 24

[RouterA-Ten-GigabitEthernet3/1/1] quit

# # Assign IP addresses to other interfaces (including the loopback interfaces) according to Figure 2. (Details not shown.)

2. Configure an LSR ID, enable MPLS, MPLS TE, and RSVP-TE on the routers:

# Configure Router A.

[RouterA] mpls lsr-id 1.1.1.1

[RouterA] mpls te

[RouterA-te] quit

[RouterA] rsvp

[RouterA-rsvp] quit

[RouterA] interface Ten-GigabitEthernet3/1/1

[RouterA-Ten-GigabitEthernet3/1/1] mpls enable

[RouterA-Ten-GigabitEthernet3/1/1] mpls te enable

[RouterA-Ten-GigabitEthernet3/1/1] rsvp enable

[RouterA-Ten-GigabitEthernet3/1/1] quit

[RouterA] interface Ten-GigabitEthernet3/1/2

[RouterA-Ten-GigabitEthernet3/1/2] mpls enable

[RouterA-Ten-GigabitEthernet3/1/2] mpls te enable

[RouterA-Ten-GigabitEthernet3/1/2] rsvp enable

[RouterA-Ten-GigabitEthernet3/1/2] quit

# Configure Router B, Router C, and Router D in the same way as you configure Route A. (Details not shown.)

3. On the MPLS backbone, configure OSPF to ensure IP connectivity between the routers, enable the OSPF Opaque capability, and enable MPLS TE in OSPF area 0:

# Configure Router A.

[RouterA] ospf

[RouterA-ospf-1] opaque-capability enable

[RouterA-ospf-1] area 0

[RouterA-ospf-1-area-0.0.0.0] mpls te enable

[RouterA-ospf-1-area-0.0.0.0] network 1.1.1.1 0.0.0.0

[RouterA-ospf-1-area-0.0.0.0] network 12.12.12.0 0.0.0.255

[RouterA-ospf-1-area-0.0.0.0] network 14.14.14.0 0.0.0.255

[RouterA-ospf-1-area-0.0.0.0] network 192.168.10.0 0.0.0.255

[RouterA-ospf-1-area-0.0.0.0] quit

[RouterA-ospf-1] quit

# Configure Router B.

[RouterB] ospf

[RouterB-ospf-1] opaque-capability enable

[RouterB-ospf-1] area 0

[RouterB-ospf-1-area-0.0.0.0] mpls te enable

[RouterB-ospf-1-area-0.0.0.0] network 2.2.2.2 0.0.0.0

[RouterB-ospf-1-area-0.0.0.0] network 12.12.12.0 0.0.0.255

[RouterB-ospf-1-area-0.0.0.0] network 23.23.23.0 0.0.0.255

[RouterB-ospf-1-area-0.0.0.0] quit

[RouterB-ospf-1] quit

# Configure Router C.

[RouterC] ospf

[RouterC-ospf-1] opaque-capability enable

[RouterC ospf-1] area 0

[RouterC-ospf-1-area-0.0.0.0] mpls te enable

[RouterC-ospf-1-area-0.0.0.0] network 3.3.3.3 0.0.0.0

[RouterC ospf-1-area-0.0.0.0] network 23.23.23.0 0.0.0.255

[RouterC ospf-1-area-0.0.0.0] network 34.34.34..0 0.0.0.255

[RouterC ospf-1-area-0.0.0.0] network 192.168.20.0 0.0.0.255

[RouterC ospf-1-area-0.0.0.0] quit

[RouterC ospf-1] quit

# Configure Router D.

[RouterD] ospf

[RouterD-ospf-1] opaque-capability enable

[RouterD-ospf-1] area 0

[RouterD-ospf-1-area-0.0.0.0] mpls te enable

[RouterD-ospf-1-area-0.0.0.0] network 4.4.4.4 0.0.0.0

[RouterD-ospf-1-area-0.0.0.0] network 14.14.14.0 0.0.0.255

[RouterD-ospf-1-area-0.0.0.0] network 34.34.34.0 0.0.0.255

[RouterD-ospf-1-area-0.0.0.0] quit

[RouterD-ospf-1] quit

4. Configure the MPLS TE tunnel:

# On Router A, create an MPLS TE tunnel named Tunnel3. Specify the destination address as the LSR ID of Router C (3.3.3.3), specify the signaling protocol as RSVP-TE, and enable CRLSP hot-standby backup for the tunnel.

[RouterA] interface tunnel 3 mode mpls-te

[RouterA-Tunnel3] ip address 9.1.1.1 255.255.255.0

[RouterA-Tunnel3] destination 3.3.3.3

[RouterA-Tunnel3] mpls te signaling rsvp-te

[RouterA-Tunnel3] mpls te backup hot-standby

[RouterA-Tunnel3] quit

# Create explicit paths for the tunnel. Configure CR-LSP 1 as the primary path and CR-LSP 2 as the backup path by setting the preference of CR-LSP 1 to 1 and that of CR-LSP 2 to 2.

[RouterA] explicit-path cr-lsp1

[RouterA-explicit-path-cr-lsp1] nexthop 12.12.12.2

[RouterA-explicit-path-cr-lsp1] quit

[RouterA]explicit-path cr-lsp2

[RouterA-explicit-path-cr-lsp2] nexthop 14.14.14.4

[RouterA-explicit-path-cr-lsp2]quit

[RouterA] interface tunnel 3

[RouterA-Tunnel3] mpls te path preference 1 explicit-path cr-lsp1

[RouterA-Tunnel3] mpls te path preference 2 explicit-path cr-lsp2

[RouterA-Tunnel3] quit

# On Router C, create an MPLS TE tunnel named Tunnel3. Specify the destination address as the LSR ID of Router A1.1.1.1), specify the signaling protocol as RSVP-TE, and enable CRLSP hot-standby backup for the tunnel.

[RouterC] interface tunnel 3 mode mpls-te

[RouterC-Tunnel3] ip address 9.3.3.3 255.255.255.0

[RouterC-Tunnel3] destination 1.1.1.1

[RouterC-Tunnel3] mpls te signaling rsvp-te

[RouterC-Tunnel3] mpls te backup hot-standby

[RouterC-Tunnel3] quit

# Create explicit paths for the tunnel. Configure CR-LSP 1 as the primary path and CR-LSP 2 as the backup path by setting the preference of CR-LSP 1 to 1 and that of CR-LSP 2 to 2.

[RouterC] explicit-path cr-lsp1

[RouterC-explicit-path-cr-lsp1] nexthop 23.23.23.2

[RouterC-explicit-path-cr-lsp1] quit

[RouterC]explicit-path cr-lsp2

[RouterC-explicit-path-cr-lsp2] nexthop 34.34.34.4

[RouterC-explicit-path-cr-lsp2]quit

[RouterC] interface tunnel 3

[RouterC-Tunnel3] mpls te path preference 1 explicit-path cr-lsp1

[RouterC-Tunnel3] mpls te path preference 2 explicit-path cr-lsp2

[RouterC-Tunnel3] quit

5. Configure a static route to direct traffic to the MPLS TE tunnel:

# On Router A, configure a static route to direct traffic destined for 192.168.20.0/24 to MPLS TE tunnel interface Tunnel3.

[RouterA] ip route-static 192.168.20.0 24 tunnel 3 preference 1

# On Router C, configure a static route to direct traffic destined for 192.168.10.0/24 to MPLS TE tunnel interface Tunnel3.

[RouterC] ip route-static 192.168.10.0 24 tunnel 3 preference 1

6. Enable BFD for MPLS, and configure BFD to verify connectivity of the MPLS TE tunnel:

# Configure Router A.

[RouterA] mpls bfd enable

[RouterA] interface tunnel 3

[RouterA-Tunnel3] mpls bfd

[RouterA-Tunnel3] quit

# Configure Router C.

[RouterC] mpls bfd enable

[RouterC] interface tunnel 3

[RouterC-Tunnel3] mpls bfd

[RouterC-Tunnel3] quit

Verifying the configuration

1. Verify that the MPLS TE tunnel has been established successfully:

# On Router A and Router C, execute the display interface tunnel command. The output shows that the tunnel state is UP. Take Router A as an example:

<RouterA> display interface tunnel

Tunnel3

Interface index: 17796

Current state: UP

Line protocol state: UP

Description: Tunnel3 Interface

Bandwidth: 64kbps

Maximum Transmit Unit: 1496

Internet Address is 9.1.1.1/24 Primary

Tunnel source unknown, destination 3.3.3.3

Tunnel TTL 255

Tunnel protocol/transport CR_LSP

Last clearing of counters: Never

Last 300 seconds input rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec

Last 300 seconds output rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec

Input: 0 packets, 0 bytes, 0 drops

Output: 0 packets, 0 bytes, 0 drops

2. On Router A, execute the tracert mpls te command to verify that the current path in use is CR-LSP1. (To use the tracert feature, you must also enable sending of ICMP time exceeded messages on the transit devices and enable sending of ICMP destination unreachable messages on the destination device.)

<RouterA>tracert mpls te Tunnel 3

MPLS trace route TE tunnel Tunnel3

TTL Replier Time Type Downstream

0 Ingress 12.12.12.2/[1140]

1 12.12.12.2 30 ms Transit 23.23.23.3/[3]

2 23.23.23.3 2 ms Egress

3. On Router A, execute the display mpls bfd command. The output shows that two BFD sessions have been created for the MPLS TE tunnel. The session for the primary CRLSP is up and that for the backup CRLSP is down. Take Router A as an example:

<RouterA>display mpls bfd te tunnel 3

Total number of sessions: 2, 1 up, 1 down, 0 init

FEC Type: TE Tunnel

FEC Info:

Send Addr: 1.1.1.1

End Addr: 3.3.3.3

Tunnel ID: 3

LSP ID : 1150

NHLFE ID: 1045

Local Discr: 1026 Remote Discr: -

Source IP: 1.1.1.1 Destination IP: 127.0.0.2

Session State: Down Session Role: Passive

Template Name: -

FEC Type: TE Tunnel

FEC Info:

Send Addr: 1.1.1.1

End Addr: 3.3.3.3

Tunnel ID: 3

LSP ID : 1151

NHLFE ID: 1047

Local Discr: 1027 Remote Discr: 515

Source IP: 1.1.1.1 Destination IP: 127.0.0.1

Session State: Up Session Role: Passive

Template Name: -

4. Continuously ping Router C from Router A. During this period, shut down Ten-GigabitEthernet 3/1/1 of Router B. Verify the communication between Router A and Router C.

# Continuously ping Router C from Router A.

<RouterA>ping -c 10000 -a 192.168.10.1 192.168.20.1

Ping 192.168.20.1 (192.168.20.1) from 192.168.10.1: 56 data bytes, press CTRL_C

to break

56 bytes from 192.168.20.1: icmp_seq=0 ttl=254 time=3.443 ms

56 bytes from 192.168.20.1: icmp_seq=1 ttl=254 time=2.835 ms

...

# Shut down Ten-GigabitEthernet 3/1/1 of Router B.

[RouterB] interface Ten-GigabitEthernet3/1/1

[RouterB-Ten-GigabitEthernet3/1/1] shutdown

# You can see that Router A and Router C resumed connectivity quickly after a short period of disconnection.

<RouterA>ping -c 10000 -a 192.168.10.1 192.168.20.1

Ping 192.168.20.1 (192.168.20.1) from 192.168.10.1: 56 data bytes, press CTRL_C

to break

56 bytes from 192.168.20.1: icmp_seq=0 ttl=254 time=3.443 ms

56 bytes from 192.168.20.1: icmp_seq=1 ttl=254 time=2.835 ms

...

56 bytes from 192.168.20.1: icmp_seq=22 ttl=254 time=3.503 ms

Request time out

56 bytes from 192.168.20.1: icmp_seq=24 ttl=254 time=2.434 ms

56 bytes from 192.168.20.1: icmp_seq=25 ttl=254 time=3.196 ms

56 bytes from 192.168.20.1: icmp_seq=26 ttl=254 time=3.592 ms

56 bytes from 192.168.20.1: icmp_seq=27 ttl=254 time=2.305 ms

56 bytes from 192.168.20.1: icmp_seq=28 ttl=254 time=2.139 ms

--- Ping statistics for 192.168.20.1 ---

29 packet(s) transmitted, 28 packet(s) received, 3.4% packet loss

round-trip min/avg/max/std-dev = 2.076/2.701/3.921/0.609 ms

5. Test whether a switchover has happened:

# On Router A, execute the tracert mpls te command. You can see the currently used path of the tunnel is CR-LSP2.

<RouterA>tracert mpls te Tunnel 3

MPLS trace route TE tunnel Tunnel3

TTL Replier Time Type Downstream

0 Ingress 14.14.14.4/[1142]

1 14.14.14.4 198 ms Transit 34.34.34.3/[3]

2 34.34.34.3 7 ms Egress

# On Router A, execute the display mpls bfd command. The output shows that a BFD session exists for the CR-LSP2 path of the tunnel and the session state is up.

<RouterA>display mpls bfd te tunnel 3

Total number of sessions: 1, 1 up, 0 down, 0 init

FEC Type: TE Tunnel

FEC Info:

Send Addr: 1.1.1.1

End Addr: 3.3.3.3

Tunnel ID: 3

LSP ID : 1151

NHLFE ID: 1047

Local Discr: 1027 Remote Discr: 515

Source IP: 1.1.1.1 Destination IP: 127.0.0.1

Session State: Up Session Role: Passive

Template Name: -

Configuration files

· Router A:

ospf 1

area 0.0.0.0

network 1.1.1.1 0.0.0.0

network 12.12.12.0 0.0.0.255

network 14.14.14.0 0.0.0.255

network 192.168.10.0 0.0.0.255

mpls te enable

mpls lsr-id 1.1.1.1

mpls te

explicit-path cr-lsp1

nexthop index 1 12.12.12.2 include strict

explicit-path cr-lsp2

nexthop index 1 14.14.14.4 include strict

rsvp

mpls bfd enable

interface LoopBack0

ip address 1.1.1.1 255.255.255.255

interface Ten-GigabitEthernet3/1/1

port link-mode route

ip address 12.12.12.1 255.255.255.0

mpls enable

mpls te enable

rsvp enable

interface Ten-GigabitEthernet3/1/2

port link-mode route

ip address 14.14.14.1 255.255.255.0

mpls enable

mpls te enable

rsvp enable

interface Ten-GigabitEthernet3/1/3

port link-mode route

ip address 192.168.10.1 255.255.255.0

interface Tunnel3 mode mpls-te

ip address 9.1.1.1 255.255.255.0

mpls te path preference 1 explicit-path cr-lsp1

mpls te path preference 2 explicit-path cr-lsp2

mpls te backup hot-standby

mpls bfd

destination 3.3.3.3

ip route-static 192.168.20.0 24 Tunnel3 preference 1

· Router B:

ospf 1

area 0.0.0.0

network 2.2.2.2 0.0.0.0

network 12.12.12.0 0.0.0.255

network 23.23.23.0 0.0.0.255

mpls te enable

mpls lsr-id 2.2.2.2

mpls te

rsvp

interface LoopBack0

ip address 2.2.2.2 255.255.255.255

interface Ten-GigabitEthernet3/1/1

port link-mode route

ip address 12.12.12.2 255.255.255.0

mpls enable

mpls te enable

rsvp enable

interface Ten-GigabitEthernet3/1/2

port link-mode route

ip address 23.23.23.2 255.255.255.0

mpls enable

mpls te enable

rsvp enable

· Router C:

ospf 1

area 0.0.0.0

network 3.3.3.3 0.0.0.0

network 23.23.23.0 0.0.0.255

network 34.34.34.0 0.0.0.255

network 192.168.20.0 0.0.0.255

mpls te enable

mpls lsr-id 3.3.3.3

mpls te

explicit-path cr-lsp1

nexthop index 1 23.23.23.2 include strict

explicit-path cr-lsp2

nexthop index 1 34.34.34.4 include strict

rsvp

mpls bfd enable

interface LoopBack0

ip address 3.3.3.3 255.255.255.255

interface Ten-GigabitEthernet3/1/1

port link-mode route

ip address 34.34.34.3 255.255.255.0

mpls enable

mpls te enable

rsvp enable

interface Ten-GigabitEthernet3/1/2

port link-mode route

ip address 23.23.23.3 255.255.255.0

mpls enable

mpls te enable

rsvp enable

interface Ten-GigabitEthernet3/1/3

port link-mode route

ip address 192.168.20.1 255.255.255.0

interface Tunnel3 mode mpls-te

ip address 9.3.3.3 255.255.255.0

mpls te path preference 1 explicit-path cr-lsp1

mpls te path preference 2 explicit-path cr-lsp2

mpls te backup hot-standby

mpls bfd

destination 1.1.1.1

ip route-static 192.168.10.0 24 Tunnel3 preference 1

· Router D:

ospf 1

area 0.0.0.0

network 4.4.4.4 0.0.0.0

network 14.14.14.0 0.0.0.255

network 34.34.34.0 0.0.0.255

mpls te enable

mpls lsr-id 4.4.4.4

mpls te

rsvp

interface LoopBack0

ip address 4.4.4.4 255.255.255.255

interface Ten-GigabitEthernet3/1/1

port link-mode route

ip address 34.34.34.4 255.255.255.0

mpls enable

mpls te enable

rsvp enable

interface Ten-GigabitEthernet3/1/2

port link-mode route

ip address 14.14.14.4 255.255.255.0

mpls enable

mpls te enable

rsvp enable

02-Configuration Examples

Introduction

Prerequisites

Example: Configuring BFD for an LSP

Network configuration

Procedures

Verifying the configuration

Configuration files

Example: Configuring BFD for an MPLS TE tunnel

Network configuration

Restrictions and guidelines

Procedures

Verifying the configuration

Configuration files

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