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NSRP fail over failed with Interface monitoring enabled due to weight settings on NSRP Interface Monitoring

  [KB17432] Show Article Properties


Summary:

NSRP fail over failed with interface monitoring enabled need to know why?

Symptoms:

NSRP fail over failed with interface monitoring enabled need to know why? Also need to know how to resolve the issue?

Solution:

NSRP fail over failed with Interface monitoring enabled due to the weigh not being set correctly. The following are steps to troubleshooting the issue and how to resolve the problem:

  • Run the following command if you are monitoring at the device level:  get nsrp monitor, and if you are monitoring at VSD level run the command get nsrp vsd-group id <id> monitor. Below is a sample output:
  • nsisg2000(M)-> get nsrp monitor
    device based nsrp monitoring threshold: 255, weighted sum: 155, not failed
    device based nsrp monitor interface: ethernet1/1(weight 155, DOWN) ethernet1/2(weight 155, UP)
    device based nsrp monitor zone:
    device based nsrp monitor security module:
    device based nsrp track ip: (weight: 255, disabled)

    In this case, the eth1/1 interface is down but the device is still master. This is because in order for a failover to happen, the device must hit a combined weight of 255. If the weight of 255 is not met, then a failover will not occur.

  • Configuration related to NSRP for this test:
  • nsisg2000(M)-> get config | i nsrp
    set nsrp cluster id 1
    set nsrp vsd-group id 0 priority 100
    set nsrp monitor interface ethernet1/1 weight 155
    set nsrp monitor interface ethernet1/2 weight 155

  • In order for a failover to happen in this situation, both interfaces will have to fail to trigger a combined weight of 255 or higher:
  • nsisg2000(I)-> get nsrp monitor
    device based nsrp monitoring threshold: 255, weighted sum: 310, failed
    device based nsrp monitor interface: ethernet1/1(weight 155, DOWN) ethernet1/2(weight 155, DOWN)
    device based nsrp monitor zone:
    device based nsrp monitor security module:
    device based nsrp track ip: (weight: 255, disabled)

    As you can see now both interfaces are down the the combine failed weight is 310 that has triggered the device to failover.

  • So the solution would be to set the weight to 255 per interface (which is the default setting).  Then if one interface fails, a failover is triggered.  For example, both of the following configurations are equivalent:
  • nsisg2000(M)-> get config | i nsrp
    set nsrp cluster id 1
    set nsrp vsd-group id 0 priority 100
    set nsrp monitor interface ethernet1/1 
    set nsrp monitor interface ethernet1/2

    OR 
    nsisg2000(M)-> get config | i nsrp
    set nsrp cluster id 1
    set nsrp vsd-group id 0 priority 100
    set nsrp monitor interface ethernet1/1 weight 255
    set nsrp monitor interface ethernet1/2 weight 255


For additional troubleshooting and explanations, refer to KB11192 - In NSRP Active/Passive environment, how do I perform a device fail over of monitored objects (Interface, Track-IP, and Zone)?.
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