IS-IS NSR configuration example

Switch S, Switch A, and Switch B belong to the same IS-IS routing domain as illustrated in Figure 67. Switch S is an IRF fabric, which is connected to Switch A and Switch B over aggregated links. Enable IS-IS NSR on Switch S to ensure correct routing when a master/slave switchover occurs on Switch S.

1. Configure IP addresses and subnet masks for interfaces on the switches. (Details not shown.)

2. Configure IS-IS on the switches, ensuring that Switch S, Switch A, and Switch B can communicate with each other at Layer 3 and dynamic route update can be implemented among them with IS-IS. (Details not shown.)

3. Enable IS-IS NSR on Switch S.

   <SwitchS> system-view
   [SwitchS] isis 1
   [SwitchS-isis-1] non-stop-routing
   [SwitchS-isis-1] non-stop-routing interval 30
   [SwitchS-isis-1] return
   

4. Verify the configuration:

   After Switch S establishes neighbor relationships with Switch A and Switch B, they start to exchange routing information. After network convergence, perform a master/slave switchover on Switch S. During the switchover period, use the display isis peer command to check the neighbor relationship between Switch A and Switch S and between Switch B and Switch S; use the display isis route command to check if routes from Switch A to the loopback interface on Switch B and from Switch B to the loopback interface on Switch A exist.

   # When a master/slave switchover occurs on Switch S, display IS-IS neighbors and routes on Switch A.

   <SwitchA> display isis peer
   
         Peer information for ISIS(1)
                             ----------------------------
   
     System Id: 0000.0000.0001
     Interface: vlan100                 Circuit Id: 0000.0000.0001.01
     State: Up     HoldTime: 25s        Type: L1(L1L2)     PRI: 64
   
     System Id: 0000.0000.0001
     Interface: vlan100                 Circuit Id: 0000.0000.0001.01
     State: Up     HoldTime: 27s        Type: L2(L1L2)     PRI: 64
   <SwitchA> display isis route
    Route information for ISIS(1)
                            -----------------------------
                        ISIS(1) IPv4 Level-1 Forwarding Table
                        -------------------------------------
   IPV4 Destination     IntCost    ExtCost ExitInterface   NextHop         Flags
   --------------------------------------------------------------------------
    12.12.12.0/24       10         NULL    vlan100         Direct          D/L/-
    22.22.22.22/32      10         NULL    Loop0           Direct          D/-/-
    14.14.14.0/32       10         NULL    vlan100         12.12.12.2      R/L/-
    44.44.44.44/32      10         NULL    vlan100         12.12.12.2      R/L/-
   
         Flags: D-Direct, R-Added to RM, L-Advertised in LSPs, U-Up/Down Bit Set
   
   
                        ISIS(1) IPv4 Level-2 Forwarding Table
                        -------------------------------------
   
    IPV4 Destination     IntCost    ExtCost ExitInterface   NextHop         Flags
   --------------------------------------------------------------------------
    12.12.12.0/24        10         NULL    vlan100         Direct          D/L/-
    22.22.22.22/32       10         NULL    Loop0           Direct          D/-/-
    14.14.14.0/32        10         NULL
    44.44.44.44/32       10         NULL
   
         Flags: D-Direct, R-Added to RM, L-Advertised in LSPs, U-Up/Down Bit Set
   

   # Display IS-IS neighbors and routes on Switch B.

   <SwitchB> display isis peer
   
         Peer information for ISIS(1)
                             ----------------------------
   
     System Id: 0000.0000.0001
     Interface: vlan200                 Circuit Id: 0000.0000.0001.01
     State: Up     HoldTime: 25s        Type: L1(L1L2)     PRI: 64
   
     System Id: 0000.0000.0001
     Interface: vlan200                 Circuit Id: 0000.0000.0001.01
     State: Up     HoldTime: 27s        Type: L2(L1L2)     PRI: 64
   <SwitchB> display isis route
    Route information for ISIS(1)
                            -----------------------------
                        ISIS(1) IPv4 Level-1 Forwarding Table
                        -------------------------------------
   IPV4 Destination     IntCost    ExtCost ExitInterface   NextHop         Flags
   --------------------------------------------------------------------------
    14.14.14.0/24       10         NULL    vlan200         Direct          D/L/-
    44.44.44.44/32      10         NULL    Loop0           Direct          D/-/-
    12.12.12.0/32       10         NULL    vlan200         14.14.14.4      R/L/-
    22.22.22.22/32      10         NULL    vlan200         14.14.14.4      R/L/-
   
         Flags: D-Direct, R-Added to RM, L-Advertised in LSPs, U-Up/Down Bit Set
   
   
                        ISIS(1) IPv4 Level-2 Forwarding Table
                        -------------------------------------
   
    IPV4 Destination     IntCost    ExtCost ExitInterface   NextHop         Flags
   --------------------------------------------------------------------------
    14.14.14.0/24        10         NULL    vlan200         Direct          D/L/-
    44.44.44.44/32       10         NULL    Loop0           Direct          D/-/-
    12.12.12.0/32        10         NULL
    22.22.22.22/32       10         NULL
   
         Flags: D-Direct, R-Added to RM, L-Advertised in LSPs, U-Up/Down Bit Set
   

   The output shows that the neighbor relationships and routing information on Switch A and Switch B have not changed. The neighbors cannot sense the switchover on Switch S.