Determining counts or size of routing table? (netstat performance?)

Mykel Mykel at
Sat Nov 29 21:09:14 PST 2008

Sam Leffler wrote:
> Julian Elischer wrote:
>> Mykel wrote:
>>> Got a few 6.x machines running OpenBGPd with a few BGP full-feeds and a
>>> handful of peers... I'd like to determine the size of the FIB/kernel
>>> routing table. OpenBGPd does not give me this data, and on my
>>> duallie-Xeon 2.8s, it takes quite a while to use netstat & wc to count.
>>> I'm not looking for exact numbers, just something I can poll via
>>> NetSNMP
>>> and plot in cacti...
>>> I looked though netstat, route, sysctl, vmstat, even pored over an
>>> snmpwalk... can't find anything.
>>> Been asking around, and the only suggestion I've received was to
>>> write a
>>> daemon that dumps the table and then monitors the changes, but I'm
>>> not a
>>> programmer, nor could I find any tool in ports that might assist in
>>> this.
>>> I'd be happy with almost any metric that gives me some absolute
>>> reference as to how big my routing table is so I can get some nice
>>> pretty graphs done up. Not pounding the system every 60-300 seconds
>>> would be very nice.
>>> Any suggestions? Or does everyone just pipe netstat? Is there a MIB for
>>> sysctl or NetSNMP I'm missing?
>> no. It's a hard thing to do so that is why it hasn't been done yet.
> Perhaps I misunderstand his question but
> trouble% vmstat -m  |grep routetbl
>     routetbl    14     2K       -    33875  16,32,64,128,256
> should show memory allocated to the routing table.
I was also shown (privately) this:

# vmstat -z | grep "rtentry"
rtentry:                  120,        0,      198,      474,   
12190,        0

Either works for me, so I'm now happy. Thanks!


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