[quagga-users 11000] Re: Linux kernel support for large FIB

Stephen Hemminger shemminger at linux-foundation.org
Thu Aug 6 17:08:27 IST 2009

On Wed, 5 Aug 2009 15:30:38 -0700
"Anirban Sinha" <ASinha at zeugmasystems.com> wrote:

> Hi All:
> We need to support about 512K routes in the kernel FIB for the BGP
> routing software built in-house. We are using off-the-shelf linux kernel
> 2.6.26 from linux-mips.org for our mips platform. Since you guys are
> already working on this BGP routing space, I am wondering if you guys
> can answer two of my questions:
> (a) Is the Linux kernel able to support the large FIB size? If not, are
> there any patches available for this support?
> (b) Are there any known performance implications for having a  very
> large number of routing entries in the kernel? We are uing about 4 gigs
> of memory (RAM).

You will get much better performance if kernel is compiled with the
FIB_TRIE option, (the default is FIB_HASH).


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