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

Sam Leffler sam at
Sat Nov 29 21:18:29 PST 2008

Mykel wrote:
> 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!

Yes, was looking for that but stopped when I found malloc's for the 
radix tree :-)


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