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Unanswered Question
Aug 21st, 2011
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we have 12410 GSR with PRP2 runinng cisco IOS, as internet gateway, running full internet routing table and peering with 7 internet BGP peers with full internet routing table update,there is high cpu utilization , and now we are planning to run dual stack IPv6/IPv4  on this internet gateway, we are not sure about the performance, please what you advise here,

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Laurent Aubert Mon, 08/22/2011 - 10:09
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Hi Ahmed,

CPU spikes are expected when BGP is processing a lot of path. If it's a real concern, you may think of moving some peers to another box or move to a more powerful machine like XR12k with PRP3. If the throughput stays globally below 40Gbps, you may also consider the asr1k family.

With the GSR, you should have only E5 LC before deplying IPv6. E5 supports 1M TCAM entries shared between IPv4 and IPv6. If A is the number of IPv4 unique routes and B the IPv6 ones, then make sure A+2B<1M

Please engage your Cisco account team as well for this discussion.



SaeedBakh_2 Mon, 08/22/2011 - 10:48
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the CPU utilization now is 55% not at BGP scaner ,at bgp scanner 100% , we have the 12410 with PRP2 with cisco IOS not XR IOS,and this is before running IPv6 , i do not know what will happend if we enable it.

i am not sure if PRP3 can solve the cpu issue and how much it will reduce.

what is the alternative chassis that can for sure solve the cpu issue and make us relaxe when we enable IPV4/IPV6 dual stack?

Laurent Aubert Mon, 08/22/2011 - 13:30
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First thing to do is to figure out why you have an average of 55% load and if this is expected or not. If it's not, you should consider feature like rACL and CoPP to protect your CPU:



PRP3 is much more powerful than PRP2 and XR by default offer better CPU protection mechanism but it's impossible to say in advance the gain you will have in your environment.

The only way to find the right gears is to test them unfortunately.

Also instead of focussing on a single hw, you may want to split the features among several boxes. Why not deploying IPv6 on dedicated lower routers like the ASR1k for example and keep IPv4 on the GSR ?



SaeedBakh_2 Mon, 08/22/2011 - 14:06
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q1) Thanks, what is the size of IPv6 full internet routing,

q2) what is more powerful In control plan and can handle more full internet routing table BGP peers with global ISP , GSR 12410 with PRP2/PRP3   or ASR9006?

we have 11 BGP peers with full internet routing table distributed in two GSR 12400 so it is difficult to invest more more in the uplinks for Ipv6 on different router just for IPv6 and also need to be redundant links

Laurent Aubert Wed, 08/24/2011 - 09:30
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Hi Ahmed,

q1: check this link out:


q2: Both PRP3 and ASR9000 RSP scale to similar number (4M IPv4 routes with 8G of memory), I don't know which one converge faster though.

Please engage your Cisco account team so they can work with you on those scaling concern you have.



SaeedBakh_2 Thu, 08/25/2011 - 00:25
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Hi is the total ipv6 for full Internet routing table now is 6000, is it 0.2 % of the full Internet routing table of ipv4, another question is prp3 ans asr 9006 with 8 giga memory what is the maximum ipv4 size support with good CPU utilization


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