4000 Router Series MPLS Configuration Guide

# On Router C, create an IP prefix list prefix-from-d that denies subnet 11.1.1.0/24. Router A

uses this list to filter FEC-label mappings received from Router D.

[RouterC] ip prefix-list prefix-from-d index 10 deny 11.1.1.0 24

# On Router C, configure label acceptance policies to filter FEC-label mappings received from

Router B and Router D.

[RouterC] mpls ldp

[RouterC-ldp] accept-label peer 2.2.2.9 prefix-list prefix-from-b

[RouterC-ldp] accept-label peer 4.4.4.9 prefix-list prefix-from-d

[RouterC-ldp] quit

Verifying the configuration

# Execute the display mpls ldp lsp command on each router to view the LDP LSP information. For example,

on Router A:

[RouterA] display mpls ldp lsp

Status Flags: * - stale, L - liberal

Statistics:

FECs: 2 Ingress LSPs: 1 Transit LSPs: 1 Egress LSPs: 1

FEC In/Out Label Nexthop OutInterface

11.1.1.0/24 1277/-

-/1148(L)

21.1.1.0/24 -/1149(L)

-/1276 10.1.1.2 S2/0

1276/1276 10.1.1.2 S2/0

The output shows that the next hop of the LSP for FEC 21.1.1.0/24 is Router B (10.1.1.2). The LSP has been

set up over the link Router A—Router B—Router C, not over the link Router A—Router D—Router C.

# On Router A, test the connectivity of the LDP LSP from Router A to Router C.

[RouterA] ping mpls -a 11.1.1.1 ipv4 21.1.1.0 24

MPLS Ping FEC: 21.1.1.0/24 : 100 data bytes

100 bytes from 20.1.1.2: Sequence=1 time=1 ms

100 bytes from 20.1.1.2: Sequence=2 time=1 ms

100 bytes from 20.1.1.2: Sequence=3 time=8 ms

100 bytes from 20.1.1.2: Sequence=4 time=2 ms

100 bytes from 20.1.1.2: Sequence=5 time=1 ms

--- FEC: 21.1.1.0/24 ping statistics ---

5 packets transmitted, 5 packets received, 0.0% packet loss

round-trip min/avg/max = 1/2/8 ms

# On Router C, test the connectivity of the LDP LSP from Router C to Router A.

[RouterC] ping mpls -a 21.1.1.1 ipv4 11.1.1.0 24

MPLS Ping FEC: 11.1.1.0/24 : 100 data bytes

100 bytes from 10.1.1.1: Sequence=1 time=1 ms

100 bytes from 10.1.1.1: Sequence=2 time=1 ms

100 bytes from 10.1.1.1: Sequence=3 time=1 ms

100 bytes from 10.1.1.1: Sequence=4 time=1 ms

100 bytes from 10.1.1.1: Sequence=5 time=1 ms