HSRP group

[jagdev.dhaliwal]

Hi All,

Is there any difference if i configure HSRP with a group or without a group

for ex:-

with group no.
interface Ethernet0
ip address 171.16.6.5 255.255.255.0
standby 1 preempt
standby 1 ip 171.16.6.1

without group no.

interface Ethernet0
ip address 171.16.6.5 255.255.255.0
standby preempt
standby ip 171.16.6.1

Thanks

JD

[Mahesh Gohil]

Hello,

The default group is 0(zero)  so if you already configured ip 171.16.6.1 for group-1 router will not allow you to configure

same ip for group 0 (default group).

Moreover both will be treated as different group.

Ans the group id will e bound to virtual-mac address of that group

for default group it will be : 0000.0c07.ac00

for group-1 it will be: 0000.0c07.ac01

Please let us know if this helps or you were searching some other info.

Regards

Mahesh

[IAN WHITMORE]

standby ip

To activate the Hot Standby Router Protocol (HSRP), use the standby ip command in interface configuration mode. To disable HSRP, use the no form of this command.

standby [group-number] ip [ip-address [secondary]]

no standby [group-number] ip [ip-address]

Syntax Description

group-number	(Optional) Group number on the interface for which HSRP is being activated. The default is 0.
ip-address	(Optional) IP address of the Hot Standby router interface.
secondary	(Optional) Indicates the IP address is a secondary Hot Standby router interface. Useful on interfaces with primary and secondary addresses; you can configure primary and secondary HSRP addresses.

Defaults

The default group number is 0
HSRP is disabled by default.

Taken from the command reference.

HTH,

Ian

[jagdev.dhaliwal]

i saw usually in every configuration there is group no is mentioned, why so

as per command reference if i do not configure any group no it should not make any difference.

[Mahesh Gohil · Accepted solution]

Hello JD,

Sorry for migguide in my earlier post.

Well configuring no group doesn't stop you to run HSRP.

I have done some testing and it works.

Interface   Grp  Pri P State   Active          Standby         Virtual IP
Fa0/0       0    100   Standby 192.168.14.3    local           192.168.14.1

But there is scenario with few of my customer where I need to configure standby group.

P1--------             -------CE1

            ---Switch-

P2-------             ------- CE2

I am catering multiple customer on switch with different vlan configured for each customer. In this case I am forced to configure vlan-id as group-id

so that I can differentiate different customer in each hsrp group.

I still agree that if there is only one hsrp group it is ok not to configure any group id (because it works with Default=0)

Hope this is helpful.

[IAN WHITMORE]

If you don't put a group it uses group no. 0 by default. Most guides put groups etc. because they use more than one group i.e. there are various groups of HSRP configured on the router.

If you only need one group, you don't need to put a no. and the router will use 0.

Regards,

Ian