Cisco Backup Link Question

Carlton Patterson · ‎07-16-2012

Hello Experts,

This is going to be tricky to try and find the words for this question, but here we go.

Is it possible to have a backup link that when the primary link goes down the backup link will assume the ip address of the primary link. In this particular case, the primary link has a number of sub-interfaces, encapsulated with dot1q with an ip address.

The device is a 12000 GSR.

I would like to know if it's possible for a backup interface to assume the role of the primary interface and take the primary interfaces ip address or in this case all the sub-interfaces?

Cheers

Carlton

Hello Experts,

This is going to be tricky to try and find the words for this question, but here we go.

Is it possible to have a backup link that when the primary link goes down the backup link will assume the ip address of the primary link. In this particular case, the primary link has a number of sub-interfaces, encapsulated with dot1q with an ip address.

The device is a 12000 GSR.

I would like to know if it's possible for a backup interface to assume the role of the primary interface and take the primary interfaces ip address or in this case all the sub-interfaces?

Cheers

Carlton

Giuseppe Larosa · ‎07-16-2012

Hello Carlton,

my understanding is that you would like to build redundancy at the access layer / edge

The use of backup command for replicating a main interface with vlan based subinterfaces is not supported. in my opinion, in 12000 GSR either running IOS or IOS XR.

Also IRB is not supported on 12000 GSR, your only option at access layer is to use an etherchannel configured as a L3 portchannel with subinterfaces

in this way IP addresses are associated to the port channel, if one member link fails you still have one member link active

the etherchannel requires that both links are terminated on the same network device so you can only achieve link fault tolerance (unless you are facing a VSS or a C3750 stack or a Nexus pair that can terminate links on different member devices)

Hope to help

Giuseppe