LDP LSP configuration example

Network requirements

Switch A, Switch B, and Switch C all support MPLS.

Configure LDP to establish LSPs between Switch A and Switch C, so subnets 11.1.1.0/24 and 21.1.1.0/24 can reach each other over MPLS.

Configure LDP to establish LSPs for only destinations 1.1.1.9/32, 2.2.2.9/32, 3.3.3.9/32, 11.1.1.0/24, and 21.1.1.0/24 on Switch A, Switch B, and Switch C.

Figure 16: Network diagram

Requirements analysis

Configuration procedure

  1. Configure IP addresses and masks for interfaces, including the loopback interfaces, as shown in Figure 16. (Details not shown.)

  2. Configure OSPF on each switch to ensure IP connectivity between them:

    # Configure Switch A.

    <SwitchA> system-view
    [SwitchA] ospf
    [SwitchA-ospf-1] area 0
    [SwitchA-ospf-1-area-0.0.0.0] network 1.1.1.9 0.0.0.0
    [SwitchA-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
    [SwitchA-ospf-1-area-0.0.0.0] network 11.1.1.0 0.0.0.255
    [SwitchA-ospf-1-area-0.0.0.0] quit
    [SwitchA-ospf-1] quit
    

    # Configure Switch B.

    <SwitchB> system-view
    [SwitchB] ospf
    [SwitchB-ospf-1] area 0
    [SwitchB-ospf-1-area-0.0.0.0] network 2.2.2.9 0.0.0.0
    [SwitchB-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
    [SwitchB-ospf-1-area-0.0.0.0] network 20.1.1.0 0.0.0.255
    [SwitchB-ospf-1-area-0.0.0.0] quit
    [SwitchB-ospf-1] quit
    

    # Configure Switch C.

    <SwitchC> system-view
    [SwitchC] ospf
    [SwitchC-ospf-1] area 0
    [SwitchC-ospf-1-area-0.0.0.0] network 3.3.3.9 0.0.0.0
    [SwitchC-ospf-1-area-0.0.0.0] network 20.1.1.0 0.0.0.255
    [SwitchC-ospf-1-area-0.0.0.0] network 21.1.1.0 0.0.0.255
    [SwitchC-ospf-1-area-0.0.0.0] quit
    [SwitchC-ospf-1] quit
    

    # Verify that the switches have learned the routes to each other. This example uses Switch A.

    [SwitchA] display ip routing-table
    
    Destinations : 21        Routes : 21
    
    Destination/Mask    Proto  Pre  Cost         NextHop         Interface
    0.0.0.0/32          Direct 0    0            127.0.0.1       InLoop0
    1.1.1.9/32          Direct 0    0            127.0.0.1       InLoop0
    2.2.2.9/32          OSPF   10   1            10.1.1.2        Vlan2
    3.3.3.9/32          OSPF   10   2            10.1.1.2        Vlan2
    10.1.1.0/24         Direct 0    0            10.1.1.1        Vlan2
    10.1.1.0/32         Direct 0    0            10.1.1.1        Vlan2
    10.1.1.1/32         Direct 0    0            127.0.0.1       InLoop0
    10.1.1.255/32       Direct 0    0            10.1.1.1        Vlan2
    11.1.1.0/24         Direct 0    0            11.1.1.1        Vlan4
    11.1.1.0/32         Direct 0    0            11.1.1.1        Vlan4
    11.1.1.1/32         Direct 0    0            127.0.0.1       InLoop0
    11.1.1.255/32       Direct 0    0            11.1.1.1        Vlan4
    20.1.1.0/24         OSPF   10   2            10.1.1.2        Vlan2
    21.1.1.0/24         OSPF   10   3            10.1.1.2        Vlan2
    127.0.0.0/8         Direct 0    0            127.0.0.1       InLoop0
    127.0.0.0/32        Direct 0    0            127.0.0.1       InLoop0
    127.0.0.1/32        Direct 0    0            127.0.0.1       InLoop0
    127.255.255.255/32  Direct 0    0            127.0.0.1       InLoop0
    224.0.0.0/4         Direct 0    0            0.0.0.0         NULL0
    224.0.0.0/24        Direct 0    0            0.0.0.0         NULL0
    255.255.255.255/32  Direct 0    0            127.0.0.1       InLoop0
    
  3. Enable MPLS and LDP:

    # Configure Switch A.

    [SwitchA] mpls lsr-id 1.1.1.9
    [SwitchA] mpls ldp
    [SwitchA-ldp] quit
    [SwitchA] interface vlan-interface 2
    [SwitchA-Vlan-interface2] mpls enable
    [SwitchA-Vlan-interface2] mpls ldp enable
    [SwitchA-Vlan-interface2] quit
    

    # Configure Switch B.

    [SwitchB] mpls lsr-id 2.2.2.9
    [SwitchB] mpls ldp
    [SwitchB-ldp] quit
    [SwitchB] interface vlan-interface 2
    [SwitchB-Vlan-interface2] mpls enable
    [SwitchB-Vlan-interface2] mpls ldp enable
    [SwitchB-Vlan-interface2] quit
    [SwitchB] interface vlan-interface 3
    [SwitchB-Vlan-interface3] mpls enable
    [SwitchB-Vlan-interface3] mpls ldp enable
    [SwitchB-Vlan-interface3] quit
    

    # Configure Switch C.

    [SwitchC] mpls lsr-id 3.3.3.9
    [SwitchC] mpls ldp
    [SwitchC-ldp] quit
    [SwitchC] interface vlan-interface 3
    [SwitchC-Vlan-interface3] mpls enable
    [SwitchC-Vlan-interface3] mpls ldp enable
    [SwitchC-Vlan-interface3] quit
    
  4. Configure LSP generation policies:

    # On Switch A, create IP prefix list switcha, and configure LDP to use only the routes permitted by the prefix list to establish LSPs.

    [SwitchA] ip prefix-list switcha index 10 permit 1.1.1.9 32
    [SwitchA] ip prefix-list switcha index 20 permit 2.2.2.9 32
    [SwitchA] ip prefix-list switcha index 30 permit 3.3.3.9 32
    [SwitchA] ip prefix-list switcha index 40 permit 11.1.1.0 24
    [SwitchA] ip prefix-list switcha index 50 permit 21.1.1.0 24
    [SwitchA] mpls ldp
    [SwitchA-ldp] lsp-trigger prefix-list switcha
    [SwitchA-ldp] quit
    

    # On Switch B, create IP prefix list switchb, and configure LDP to use only the routes permitted by the prefix list to establish LSPs.

    [SwitchB] ip prefix-list switchb index 10 permit 1.1.1.9 32
    [SwitchB] ip prefix-list switchb index 20 permit 2.2.2.9 32
    [SwitchB] ip prefix-list switchb index 30 permit 3.3.3.9 32
    [SwitchB] ip prefix-list switchb index 40 permit 11.1.1.0 24
    [SwitchB] ip prefix-list switchb index 50 permit 21.1.1.0 24
    [SwitchB] mpls ldp
    [SwitchB-ldp] lsp-trigger prefix-list switchb
    [SwitchB-ldp] quit
    

    # On Switch C, create IP prefix list switchc, and configure LDP to use only the routes permitted by the prefix list to establish LSPs.

    [SwitchC] ip prefix-list switchc index 10 permit 1.1.1.9 32
    [SwitchC] ip prefix-list switchc index 20 permit 2.2.2.9 32
    [SwitchC] ip prefix-list switchc index 30 permit 3.3.3.9 32
    [SwitchC] ip prefix-list switchc index 40 permit 11.1.1.0 24
    [SwitchC] ip prefix-list switchc index 50 permit 21.1.1.0 24
    [SwitchC] mpls ldp
    [SwitchC-ldp] lsp-trigger prefix-list switchc
    [SwitchC-ldp] quit
    

Verifying the configuration

# Display LDP LSP information on each switch. This example uses Switch A.

[SwitchA] display mpls ldp lsp
Status Flags: * - stale, L - liberal
Statistics:
  FECs: 5      Ingress LSPs: 3     Transit LSPs: 3     Egress LSPs: 2

FEC                In/Out Label        Nexthop         OutInterface
1.1.1.9/32         3/-
                   -/1279(L)
2.2.2.9/32         -/3                 10.1.1.2        Vlan-int2
                   1279/3              10.1.1.2        Vlan-int2
3.3.3.9/32         -/1278              10.1.1.2        Vlan-int2
                   1278/1278           10.1.1.2        Vlan-int2
11.1.1.0/24        1277/-
                   -/1277(L)
21.1.1.0/24        -/1276              10.1.1.2        Vlan-int2
                   1276/1276           10.1.1.2        Vlan-int2

# Test the connectivity of the LDP LSP from Switch A to Switch C.

[SwitchA] 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

# Test the connectivity of the LDP LSP from Switch C to Switch A.

[SwitchC] 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

--- FEC: 11.1.1.0/24 ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max = 1/1/1 ms