FHRP ISSUE WITH INTERFACE TRACKING

[Farooq Muhammad]

Hi All,

I have the attached design with core,distribution and access layers and HSRP is implemented as FHRP at distribution switches for different SVIs.If know how to track the single link from Dist A  to CORE A inwhich if this link goes down then DIST B will become active but what if after then  any or both of DIST B's links to the CORE devices gets down is there any way of tracking those interfaces of DIST B by DIST A because if that is not possible then our DIST A will have reachability to CORE 2 but will be unreachable by our users at the Access layer as DIST B will continue to be  in HSRP ACTIVE STATE.

Regards in Advance.

[Peter Paluch]

Hello,

Can you perhaps post your topology in a format that does not require specialized software? I am afraid I cannot open VSD files under Linux

Anyway, I believe what you asking for is called IP SLA. The IP SLA in this case is an active configured probe on a Cisco device that can test the connectivity with a different device in a number of ways. For you, the ICMP pings would be just fine. Depending on the result of this probe, you can make your HSRP come up or down. In essence, you would be tracking the result of the IP SLA probe just as you would track the state of an interface.

There are many examples and use cases with the IP SLA feature, e.g. here:

https://supportforums.cisco.com/message/3731502#3731502

Although this thread does not discuss the usage of IP SLA with the HSRP, I am quite sure you would be able to adapt the configuration for your needs. Of course, if there are any doubts or further questions, you are welcome.

Best regards,

Peter

[Farooq Muhammad]

Hi Peter,

IP SLA is in my mind but i am insearch of any HSRP config that may have some sort of rythm in its state like this

When all is well -- both uplinks to core 1 and 2 of both DIST A  and DIST B are available so DIST A is ACTIVE

1) UPLINK 1, of DIST A down , interface tracked and  now   DIST B takes over as  ACTIVE.

2) UPLINK 1 , of DIST B down,  interface tracked and now    DIST A takes over as  ACTIVE.

3) UPLINK 2 of  DIST A down(keep in mind UPLINK 1 DIST A and DIST B already DOWN) so now DIST B takes over.

I think it is clear now.

[Giuseppe Larosa]

Hello Farooq,

HSRP allows for tracking of multiple interfaces at the same time, and if preemption is enabled the HSRP active role is performed by the device with the higher priority.

So all you need is to start with an higher priority on DISTA like 105, use default 100 priority on DISTB then each interface tracked will cause by default a 10 points decrease in priority when the tracked interface fails and you have the desired behaviour.

DISTA:

standby N priority 105

standby N preempt

standby N track interface type x1/y1

standby N track interface type x2/y2

DISTB:

standby N priority 100

standby N preempt

standby N track interface type x1/y1

standby N track interface type x2/y2

Edit:

the actual command syntax may be different in recent IOS releases using explict object tracking see below, however you should have got the idea

http://www.cisco.com/en/US/docs/ios-xml/ios/ipapp_fhrp/configuration/12-4t/fhp-hsrp.html#GUID-81342640-9DDC-4396-A48F-C9AE7D6BBFCB

Hope to help

Giuseppe

[Farooq Muhammad]

Thanks Giuseppe  for your input i will try this in the lab tomorrow and will update you about the results.