ASR1001 Redundancy for multi-homed BGP setup

[0rsnaric]

We currently have a single ASR1001-X at our edge, peering with 3 different ISPs to share our public IP space.  The ISP connections terminate in to a switch, each on their own VLAN.  The ASR has a 10G interface, with sub-interfaces also in each VLAN.

We have a second ASR that I would like to add, preferably as a HA pair, active/standby.  I've been reading up on Interchasis redundancy, but can't seem to wrap my head around the BGP portion. 

Is this doable?

Thanks!

[Reza Sharifi]

You can't cluster the ASR series. You can install the second ASR and use HSRP between them for redundancy.

HTH

[mattjones03 · Accepted solution]

Hi,

I would suggest the following (high level);

1. Connect ASR(1) and ASR(2) to your WAN switch, ensuring each ASR is associated with the correct VLAN for each ISP.

2. Establish iBGP between each of the ASR routers.

3. Establish adjacencies with the ISP routers from both ASR(1) and ASR(2).

4. Work with your ISPs to establish a path preference [ASR(1) = Primary & ASR(2) = Secondary].

5. Based on point four, ensure that your first hop resilience (HSRP/VRRP) uses a tracking/ip spa statement to decrement it’s advertised priority should the ISP side interface fail. Also, ensure that you configure preemptive failover for when a priority change takes place.

6. Finally, ensure that you are advertising your networks from both ASR routers upstream to your ISPs

Here is some further reading that will provide some context, and greater examples;

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13762-40.html