Example for Configuring a Policy for Triggering Transit LSP Establishment

Procedure

1. Configure IP addresses for interfaces.

   # Configure LSRA. The configurations of LSRB, LSRC, and LSRD are similar to the configuration of LSRA, and are not mentioned here.

   <Huawei> system-view
   [Huawei] sysname LSRA
   [LSRA] interface loopback 0
   [LSRA-LoopBack0] ip address 10.10.1.1 32
   [LSRA-LoopBack0] quit
   [LSRA] interface gigabitethernet 1/0/0
   [LSRA-GigabitEthernet1/0/0] ip address 10.1.1.1 24
   [LSRA-GigabitEthernet1/0/0] quit

2. Configure OSPF to advertise the network segments connecting to interfaces on each node and to advertise the routes of hosts with LSR IDs.

   # Configure LSRA. The configurations of LSRB, LSRC, and LSRD are similar to the configuration of LSRA, and are not mentioned here.

   [LSRA] ospf 1
   [LSRA-ospf-1] area 0
   [LSRA-ospf-1-area-0.0.0.0] network 10.10.1.1 0.0.0.0
   [LSRA-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
   [LSRA-ospf-1-area-0.0.0.0] quit
   [LSRA-ospf-1] quit

3. Configure basic MPLS and MPLS LDP functions on the nodes and interfaces

   # Configure LSRA. The configurations of LSRB, LSRC, and LSRD are similar to the configuration of LSRA, and are not mentioned here.

   [LSRA] mpls lsr-id 10.10.1.1  
   [LSRA] mpls
   [LSRA-mpls] quit  
   [LSRA] mpls ldp  
   [LSRA-mpls-ldp] quit  
   [LSRA] interface gigabitethernet 1/0/0  
   [LSRA-GigabitEthernet1/0/0] mpls  
   [LSRA-GigabitEthernet1/0/0] mpls ldp
   [LSRA-GigabitEthernet1/0/0] quit

   # Run the display mpls ldp lsp command on each node to view the establishment of the LDP LSPs. LSRA is used as an example.

   [LSRA] display mpls ldp lsp
      
    LDP LSP Information
    -------------------------------------------------------------------------------
    DestAddress/Mask   In/OutLabel    UpstreamPeer    NextHop          OutInterface
    -------------------------------------------------------------------------------
    10.10.1.1/32       3/NULL         10.10.1.2       127.0.0.1        InLoop0
   *10.10.1.1/32       Liberal/3                      DS/10.10.1.2
    10.10.1.2/32       NULL/3         -               10.1.1.2         GE1/0/0
    10.10.1.2/32       1024/3         10.10.1.2       10.1.1.2         GE1/0/0
    10.10.1.3/32       NULL/1025      -               10.1.1.2         GE1/0/0
    10.10.1.3/32       1022/1025      10.10.1.2       10.1.1.2         GE1/0/0
    10.10.1.4/32       NULL/4118      -               10.1.1.2         GE1/0/0
    10.10.1.4/32       4105/4118      10.10.1.2       10.1.1.2         GE1/0/0
    ------------------------------------------------------------------------------
    TOTAL: 7 Normal LSP(s) Found.
    TOTAL: 1 Liberal LSP(s) Found.
    TOTAL: 0 Frr LSP(s) Found.
    A '*' before an LSP means the LSP is not established
    A '*' before a Label means the USCB or DSCB is stale
    A '*' before a UpstreamPeer means the session is state
    A '*' before a DS means the session is state
    A '*' before a NextHop means the LSP is FRR LSP
   

4. Configure an IP prefix list on transit node LSRB to filter out routes on transit node LSRB.

   # Configure the IP prefix list on transit node LSRB to allow only 10.10.1.4/32 on LSRD to establish the transit LSP.

   [LSRB]ip ip-prefix FilterOnTransit permit 10.10.1.4 32  
   [LSRB] mpls ldp 
   [LSRB-mpls-ldp] propagate mapping for ip-prefix FilterOnTransit 
   [LSRB-mpls-ldp] quit
   

5. Verify the configuration.

   # Run the display mpls ldp lsp command on each node to view the establishment of the LDP LSPs. LSRA is used as an example.

   [LSRA] display mpls ldp lsp  
   
    LDP LSP Information
    -------------------------------------------------------------------------------
    DestAddress/Mask   In/OutLabel    UpstreamPeer    NextHop          OutInterface
    -------------------------------------------------------------------------------
    10.10.1.1/32       3/NULL         10.10.1.2       127.0.0.1        InLoop0
    10.10.1.2/32       NULL/3         -               10.1.1.2         GE1/0/0
    10.10.1.2/32       1024/3         10.10.1.2       10.1.1.2         GE1/0/0
    10.10.1.4/32       NULL/4118      -               10.1.1.2         GE1/0/0
    10.10.1.4/32       4105/4118      10.10.1.2       10.1.1.2         GE1/0/0
    --------------------------------------------------------------------------
    TOTAL: 5 Normal LSP(s) Found.
    TOTAL: 0 Liberal LSP(s) Found.
    TOTAL: 0 Frr LSP(s) Found.
    A '*' before an LSP means the LSP is not established
    A '*' before a Label means the USCB or DSCB is stale
    A '*' before a UpstreamPeer means the session is state
    A '*' before a DS means the session is state
    A '*' before a NextHop means the LSP is FRR LSP
   

   The preceding command output shows that only the LDP LSP to the destination 10.10.1.2/32 and 10.10.1.4/32 that takes LSRA as the ingress node exists on each node, and other LDP LSPs that do not take LSRA as the ingress node exist on each node. This is because the IP prefix list is configured.