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

Sam Leffler sam at
Sat Nov 29 21:04:35 PST 2008

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.


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