Step 2: Verify That the Secondary Path Is Established

When the secondary path is configured with the standby statement, the secondary path should be up but not active; it will become active if the primary path fails. A secondary path configured without the standby statement will not come up unless the primary path fails. To test that the secondary path is correctly configured and would come up if the primary path were to fail, you must deactivate a link or node critical to the primary path, then issue the show mpls lsp lsp-path-name extensive command.

Action

To verify that the secondary path is established, enter the following JUNOS CLI operational mode command:

user@R1>show mpls lsp extensive

Sample Output

The following sample output shows a correctly configured secondary path before and after it comes up. In the example, interface fe-0/1/0 on R2 is deactivated, which brings down the primary path via-r2. The ingress router R1 switches traffic to the secondary path via-r7.

user@R1> show mpls lsp extensive

Ingress LSP: 1 sessions

192.168.5.1

  From: 192.168.1.1, State: Up, ActiveRoute: 0, LSPname: r1-to-r5

  ActivePath: via-r2 (primary)

  LoadBalance: Random

  Encoding type: Packet, Switching type: Packet, GPID: IPv4

 *Primary   via-r2           State: Up

    Priorities: 6 6

    Bandwidth: 35Mbps

    SmartOptimizeTimer: 180

    Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 3)

 10.0.12.14 S 10.0.24.2 S 10.0.45.2 S

    Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 
10=SoftPreempt):

          10.0.12.14 10.0.24.2 10.0.45.2

    5 Apr 29 14:40:43 Selected as active path

    4 Apr 29 14:40:43 Record Route:  10.0.12.14 10.0.24.2

    3 Apr 29 14:40:43 Up

    2 Apr 29 14:40:43 Originate Call

    1 Apr 29 14:40:43 CSPF: computation result accepted

  Secondary via-r7           State: Dn

    SmartOptimizeTimer: 180

        No computed ERO.

  Created: Sat Apr 29 14:40:43 2006

Total 1 displayed, Up 1, Down 0

[edit interfaces]

user@R2# deactivate fe-0/1/0 

[edit interfaces]

user@R2# show

inactive: fe-0/1/0 {

    unit 0 {

        family inet {

            address 10.0.12.14/30;

        }

        family iso;

        family mpls;

    }

}

user@R1> show mpls lsp name r1-to-r4 extensive     

Ingress LSP: 1 sessions

192.168.4.1

  From: 192.168.1.1, State: Up, ActiveRoute: 0, LSPname: r1-to-r4

  ActivePath: via-r7 (secondary)

  LoadBalance: Random

  Encoding type: Packet, Switching type: Packet, GPID: IPv4

  Primary   via-r2           State: Dn

    Priorities: 6 6

    Bandwidth: 35Mbps

    SmartOptimizeTimer: 180

    Will be enqueued for recomputation in 14 second(s).

   10 Apr 29 14:52:33 CSPF failed: no route toward 10.0.12.14[21 times]

    9 Apr 29 14:42:48 Clear Call

    8 Apr 29 14:42:48 Deselected as active

    7 Apr 29 14:42:48 Session preempted

    6 Apr 29 14:42:48 Down

    5 Apr 29 14:40:43 Selected as active path

    4 Apr 29 14:40:43 Record Route:  10.0.12.14 10.0.24.2

    3 Apr 29 14:40:43 Up

    2 Apr 29 14:40:43 Originate Call

    1 Apr 29 14:40:43 CSPF: computation result accepted

 *Standby   via-r7           State: Up

    SmartOptimizeTimer: 180

    Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 11)

 10.0.17.14 S 10.0.47.1 S 

    Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 
10=SoftPreempt):

          10.0.17.14 10.0.47.1

    5 Apr 29 14:42:48 Selected as active path

    4 Apr 29 14:41:12 Record Route:  10.0.17.14 10.0.47.1

    3 Apr 29 14:41:12 Up

    2 Apr 29 14:41:12 Originate Call

    1 Apr 29 14:41:12 CSPF: computation result accepted

  Created: Sat Apr 29 14:40:43 2006

Total 1 displayed, Up 1, Down 0

What It Means

The sample output from egress router R1 shows a correctly configured standby secondary path in a down state because the primary path is still up. Upon deactivation of an interface (interface fe-0/1/0 on R2) critical to the primary path, the primary path via-r2 goes down and the standby secondary path via-r7 comes up, allowing R1 to switch traffic to the standby secondary path.