I've got a 2821 that is choking on my ISP's BGP table. But everything I see online indicates that I have enough memory. I understand that CEF uses the same space on the DRAM as the BGP table, but that CEF doesn't use much space. A sh ver output:
Cisco 2821 (revision 53.51) with 251904K/10240K bytes of memory.
I'd like to know what the two numbers indicate, and if it's possible to reallocate the memory. Any other light that someone can shed will be helpful.
Just to add something Terry's comment. If you are not advertising anything special to you ISP. The easiest solution would be just to remove BGP and configure a static default route, Since there is really no use for BGP at this point.
When you look at the numbers in the show version they tell you how much memory for main processing/how much memory for I/O packet processing. You add them together to get the amount of memory in the router. And it looks like your 2821 has 256 MB of memory.
You tell us that you are running BGP with your ISP but you do not tell us what the ISP is advertising to you. Based on the symptoms that you describe I will make a guess that the ISP is advertising the full BGP table to you. And I will suggest that your 2821 does not have enough memory to do that. I am not clear what you have been looking at on line, but what I see generally says you should have 512 MB to process full BGP tables.
If I am correct in understanding your problem there are several alternatives that you can consider to reesolve it:
- upgrade memory on the 2821.
- replace the 2821 with a stronger router with more memory.
- negotiate with your ISP so that they do not advertise the entire BGP table.
If you are single homed (connected to a single ISP) then I see little advantage in receiving the full BGP table from them. If they advertise just a default route (or perhaps a default route and their directly connected customer routes) then you have plenty of memory - and enough content in your routing table to process what you need.