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Community Member

BGP on a 4700 (memory/cpu concerns)

I've got a 4700 with 64 megs of memory and I'm planning on running BGP soon. I'm also currently using OSPF to do bandwidth averaging across two serial circuits and I see the CPU usage on my router get as high as 15% when these circuits close to 100% utilization..

Is a 4700 likely to be able to cope with the CPU and memory requirements of BGP? I'm assuming I'll need to do a fair amount of filtering which route announcements the router accepts?

Anyone out there currently running BGP on a 4700 with 64 megs of mem?

Community Member

Re: BGP on a 4700 (memory/cpu concerns)

How many AS/Peers and routing entries will be on the BGP network??? Will it be a very stable network?

4700 works fine for a small (or not too big) BGP networks. CPU will go up when you have a lot of routing lookup, or no CEF/fast switch. But, other than that, I have few 4700 work great for least few years.


Community Member

Re: BGP on a 4700 (memory/cpu concerns)

I'll have only 2 peers, and hopefully it will be a VERY stable network. :-) With one of the two peers we've started having some occasional outages (which is why we installed the 2nd circuit). The outages aren't very frequent, but they've been... well... less than stellar about getting the circuit back up quickly.

I need to have an access-list on each of the two interfaces going to the peers. And if memory serves this means CEF is disabled, right? So far the access-lists don't seem to impose much CPU usage, however.

Thanks for the reply!


Community Member

Re: BGP on a 4700 (memory/cpu concerns)

It depends how you intend to run your router, if you are going to take the full bgp routing table from your ISP you will need as big and as powerful a router as you can afford, the current routing table is 100,000 routes+, if you are also running CEF and other processes, you might struggle with 64Mb, if you get close to the memory threshold a lot of weird faults often occur. Solution: get your ISP to send you a default route.You dont want to do any filtering on your router ,because you obviously want to see all routes to the internet. The ISP will filter on its side to make sure you only send them the prefix you are paying and/or responsible for.

Community Member

Re: BGP on a 4700 (memory/cpu concerns)

Hi Brent,

Read "Achieve Optimal Routing and Reduce BGP Memory Consumption":

Best regards,


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