HSRP does not its number

[eigrpy]

Hi I notice some of HSRP configuration does not have hsrp number. Please see the below config. What is difference between having number and no number ? Thank you

interface Vlan3
 ip address 192.30.32.3 255.255.255.0
 standby ip 192.30.32.1
 standby priority 110
 standby preempt

[John Blakley · Accepted solution]

Without a specified group, the default is 0. If you do a "show standby", you should be able to see this by the interface description:

R2(config-if)#do sh standby
FastEthernet0/0 - Group 0
  State is Standby
    1 state change, last state change 00:04:23
  Virtual IP address is 192.168.12.2

HTH,

John

[Steve Fuller · Accepted solution]

In addition to John has said, remember that the HSRP MAC address is derived from the HSRP group number. If you have multiple interfaces on the same router each running HSRP without a group specified, these would all have the same HSRP MAC address.

This is not a problem as the MACs will exist in different subnets / VLANs, but it's something to consider. If you're looking for a MAC address during a troubleshoot, to find the same MAC address in different VLANs can sometimes confuse.

A common practice is to use the same number for the HSRP group as for the VLAN, but this scheme obviously only works within the limits of the HSRP group range i.e., up to 255.

Regards

[eigrpy]

Thank you for your reply. You  are right. We should use group number based on what you said. I notice that there are several groups of hsrp which do not use the number in one C6500. Why dont they use the group number ? what benefit is it if using non group number ? 

[Ganesh Hariharan]

Thank you for your reply. You  are right. We should use group number based on what you said. I notice that there are several groups of hsrp which do not use the number in one C6500. Why dont they use the group number ? what benefit is it if using non group number ? 

Hi , There could be many reason for that ..like they would be having small number of vlans required for redundancy. Better recommendation is to have hsrp group number aligned with vlan number for better troubleshooting purpose.

HTH

-- GI

Rate if it helps..