BGP with HSRP

[fri]

Hi All,

Current we have 2 site point to point connection.

Site A and Site B is form BGP neighbour, and LAN with HSRP configuration.

Site A pri - A01 pri.txt

Site A Sec - A02 sec.txt

Site B pri - B01 pri.txt

Site B sec - B02 sec.txt

The issue is when we shutdown the port in LAN Pri in Site B the traffic is unable to passthrough via Sec router.

When we shutdown both Site A and B primary link then the traffic is passthrough correctly.

My question its possible if either Site A or B Primary link down and automatic failover via Sec link?

[Giuseppe Larosa]

Hello @fri ,

you are using iBGP everywhere and this is the root cause of your issue.

the BGP sessions between A0x ---- Box  should be eBGP sessions means that B routers should use a different BGP As number.

It is correct to have an iBGP session between co-located routers but to be effective inter site BGP sessions have to be of type eBGP.

A router can advertise a route learned by an eBGP peer to an iBGP peer.

A router cannot advertise a route learned from an iBGP peer to another iBGP peer ( this is called iBGP split horizon rule).

I would suggest to change your design accordingly using a different AS number on B0x routers.

In alternative you need to define a full mesh of iBGP sessions

A01 --> A02

A01 --> B01

A01 ---> B02

and so on ....

Hope to help

Giuseppe

[fri]

Hi @Giuseppe Larosa,

I have make it on different AS on other site, its can route now if we disconnect the LAN the HSRP is failover and traffic is pass correct.

But when we shutdown on WAN port example in A01 primary g0/0/0 100.1.1.1, the HSRP will refering the route to A01 since LAN is no down, how we can do if we want to either LAN or WAN is down then failover to A02 secondary.

Please advise.