router design query

[Jonn cos]

Hi All,

Currently one of my client is using single ASR 1000 as its WAN core. Branhces have 2 ISPs, and both these ISPs are connected to this ASR. Now since its a single point of failure, we need to introduce another ASR 1000. But i am getting confused as how to design it. Shall i

• Bring one ISP on first ASR and second on the other ? will that be a good design
• Introduce a switch, terminate all ISP links on this switch and connect both ASRs to this switch, but then how to manage the ISP links (all links have /30 IP subnets). I thought of connecting both ASRs directly and via EEM, i thought of configuring a keepalive mechanism on new ASR. If the first ASR goes down, it will automatically turn on the links but than branches will face disruption.

What is the better design ? i tried looking at cisco validated designs but dont knw which document to look for

[Iqbal Shaikh]

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

I think this can help you.

[Joseph W. Doherty]

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Posting

If the device doesn't support hardware redundancy, then common solution is to use a second device.  So, using a second router, for the 2nd ISP, would be a common approach.  BTW, although you're using an ASR 1k now, the second device could be some other kind of device.

If you install a second HQ device, don't forget you want, if possible, not have other single points of failure.  For example, if both devices only connect to the same switch, and it doesn't support hardware redundancy, failure of that switch would drop you WAN.