ISR 921 Tunnel GRE performance

[m.castricone]

Hi all,

I need some branch routers to encapsulate multicast traffic over a GRE Tunnel to route the traffic over a WAN MPLS network. I used the 1941 model over the last year, they perform quite well until 70-80 Mbps. I'm going to replace them with the new ISR900 routers. What would be the expected performance of these family ? I hope that they can overtake the 1941 and manage over 100 Mbps of throughput with lower CPU usage.

Thanks in advance

Massimo

[balaji.bandi · Accepted solution]

here is the performance FAQ for the 921 :

https://www.cisco.com/c/dam/en/us/products/collateral/routers/900-series-integrated-services-routers-isr/q-and-a-c67-741630.pdf

[Deepak Kumar]

Hi,

Check the details here:

https://www.cisco.com/c/en/us/products/collateral/routers/900-series-integrated-services-routers-isr/datasheet-c78-741615.html

https://www.cisco.com/c/dam/en/us/products/collateral/routers/900-series-integrated-services-routers-isr/q-and-a-c67-741630.pdf

[Joseph W. Doherty]

In addition to performance documentation references provided by the other posters, doing GRE will likely diminish maximum throughput (don't believe I noticed a mention of this in the referenced documentation). If so, I would suggest perhaps allowing for up to a 10% additional CPU load if packets don't need to be fragmented and also perhaps up to about 25% if packets do need to be fragmented.

If case you've not already seen in, an excellent Cisco technote, dealing with avoiding fragmentation on tunnels, can be found here: https://www.cisco.com/c/en/us/support/docs/ip/generic-routing-encapsulation-gre/25885-pmtud-ipfrag.html