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FollowMeNet
Beginner

Configuring HSRP for specific subnets only in an existing enviroment.

I have two 6800s that have layer 2 and 3 links between them. I want to configure HSRP for specific subnets only on the two routers located 10 miles from each other. I want the existing subnets not to participate in the HSRP Active/Passive redundancy.

 

If I have subnets, for example, R1-Active (10.1.1.0/10.2.2.0) and R-2 Passive (10.3.3.0/10.4.4.0), and I add HSRP(New) for one subnet (10.20.20.0) will it treat all the subnets that are not configured for HSRP as Active Passive, meaning if R2 is passive, will it be able to pass traffic to other networks? Does it automatically make the router/subnets A/P?

 

Is the only way to get this going is to have all the SVI's configured for HSRP on both ends? We have many subnets\SVI's on both locations.

 

I tested It in a virtual lab, but it appeared that subnets that were in the passive router were unable to ping.

 

 

 

 

At each location, we have a collapsed core. All-access switches connect directly to the core.

 

3 REPLIES 3
Reza Sharifi
Hall of Fame Expert

I add HSRP(New) for one subnet (10.20.20.0) will it treat all the subnets that are not configured for HSRP as Active Passive,

No, you configure HSRP per SVI. So any other SVI/subnet that does not have the HSRP config will not be part of HSRP active/standby.

HTH

Actually, you can create multiple HSRP groups on one L3 interface. Each device participating in the group has a priority which decides what the Active is going to be for that group. The second best will become Standby, all the others will become Listeners.

If you add the new group (10.20.20.0) it will only become Active on the device with the highest priority for that group. The other groups are not affected.

For instance, if you configure the groups as follows:

Router A:

interface VLAN10
 ip add 10.1.1.253 255.255.255.0
 !
 standby 10 priority 100
 standby 10 preempt delay minimum 30
 standby 10 ip 10.1.1.254
 !
 standby 20 priority 90
 standby 20 preempt
 standby 20 ip 10.2.2.254
!

Router B:

interface VLAN10
 ip add 10.1.1.252 255.255.255.0
 !
 standby 10 priority 90
 standby 10 preempt
 standby 10 ip 10.1.1.254
 !
 standby 20 priority 100
 standby 20 preempt delay minimum 30
 standby 20 ip 10.2.2.254
!

Router A will be Active for group 10 (10.1.1.0) and router B will be active for group 20 (10.2.2.0).

MHM Cisco World
Collaborator

if you want to make the router is HSRP of specific VLAN not the MLS,

only don't config any SVI in MLS and config router interface connect to MLS with HSRP.

in this way the MLS will be as L2 for router HSRP.