%FHRP group not consistent with already configured groups on the switch stack

Unanswered Question
Jan 13th, 2010

We get this error message if we try to do hsrp stanby group number over 999. Switch is 3750 stack. E.g syntax "standby 2844 ip x.x.x.x
does not work and error "%FHRP group not consistent with already configured groups on the switch stack" appears. If group number is lower than 1000 it goes OK to config. Any idea. Switch stack pair is WS-C3750G-24TS-E and ios c3750-ipservicesk9-mz.122-53.SE.bin. Thanks Juha

I have this problem too.
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Ganesh Hariharan Wed, 01/13/2010 - 03:21

Hi Juha,

The Catalyst 3550 can only support a maximum of 16 unique group numbers.Each of the 16 unique group numbers can be used by 16 consecutive Layer 3 interfaces, which gives a total maximum of 256 HSRP interfaces. The total number that is recommended is 64, but this number depends on the routing protocols and features that are configured on the box. If you configure too many HSRP interfaces, you could cause the CPU load on the switch to become too high, which can have unexpected side effects.

The HSRP group IDs do not have to be contiguous. You can pick any 16 group IDs in the allowed group ID range (0-255). Only 16 group IDs, however, can be used from that range.

Hope that clear your query !!

Regards

Ganesh.H

u346874_2 Wed, 01/13/2010 - 04:28

Hi and thanks for answer.

Switch is WS-C3750G-24TS-E. we tryed config like below. Tryed to take standby ver 2 to production.

interface Vlan2842
ip vrf forwarding test
ip address 10.1.1.1 255.255.255.240
standby version 2
standby 2842 ip x.x.x.x
standby 2842 priority 94
standby 2842 preempt

Another stack pair accepted "standby 2842 ip x.x.x.x" but another not what was configured before. So From another stack pair entry " standby 2842 ip x.x.x.x disappears. New interfaces did not accept config  "standby 2842 ip x.x.x.x" at all and error message appears. All interfaces which group number was less than 1000 all went OK and new interfaces and group numbers less than 1000 was able to create.

Ganesh Hariharan Wed, 01/13/2010 - 23:13

Hi ,

Check out the below limitation for HSRP version 2

Restrictions for HSRP Version 2

HSRP version 2 is not available for ATM interfaces running LAN emulation.

HSRP version 2 will not interoperate with HSRP version 1. An interface cannot operate both version 1 and version 2 because both versions are mutually exclusive. However, the different versions can be run on different physical interfaces of the same router. You cannot change from version 2 to version 1 if you have configured groups above the group number range allowed for version 1 (0 to 255).

and check out the link on HSRP version 2 hope that clear your query !!

http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gthsrpv2.html

Regards

Ganesh.H

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