paket loss on freebsd router if (b)snmpd is running##SPAM

[Thomas]

Hello Harti

Harti Brandt schrieb:
> On Fri, 27 Oct 2006, Thomas wrote:
> 
> T>Hello
> T>
> T>I use several 5.4 and 6.1 FBSD machines as router (with quagga). The
> T>average traffic is 300mbit/s (em interfaces with polling enabled). It
> T>works more or less.
> T>
> T>Problem:
> T>If bsnmpd is running and I'm doing a snmpwalk from a remote machine the
> T>router has some significant packet loss. We are talking about 3-15% of
> T>packet loss. It's a simple snmpwalk (ipRouteTable and the interfaces stats).
> 
> Does this happen also if you walk only the interface tables? What size is 
> your routing table?

The routing table has approx. 200k entries. I've to correct my
statement. I don't walk over the RoutingTable.

It's only an interface table walk (IF-MIB). bsnmpd consumes approx.
6-10% cpu. I already have significant packet loss if bsnmpd is started.

bsnmpd not running:

ping www.switch.ch

--- oreius.switch.ch ping statistics ---
44 packets transmitted, 44 packets received, 0% packet loss
round-trip min/avg/max/stddev = 6.825/7.425/8.007/0.252 ms

zero packet loss.


netstat -w 1 shows no error.

            input        (Total)           output
   packets  errs      bytes    packets  errs      bytes colls
     39877     0   34330807      38614     0   34087518     0
     45522     0   38730142      44124     0   38424881     0
     44671     0   38783909      43455     0   38604698     0
     43140     0   36939542      42059     0   36691583     0
     43428     0   36858817      42213     0   36700954     0
     43748     0   37994949      42687     0   37780190     0
     42698     0   36451927      41409     0   36270936     0
     38695     0   32184588      37119     0   31791417     0




bsnmpd started:

ping www.switch.ch
--- oreius.switch.ch ping statistics ---
57 packets transmitted, 53 packets received, 7% packet loss
round-trip min/avg/max/stddev = 6.715/12.638/95.183/19.041 ms

7% packet loss.


netstat shows some errors too.
netstat -w 1
            input        (Total)           output
   packets  errs      bytes    packets  errs      bytes colls
     33597     0   27508009      32433     0   27344720     0
     38204     0   32117848      36950     0   31852251     0
     39171     0   33870984      37999     0   33696346     0
     32160     0   26825650      31065     0   26591079     0
     26915   726   20902878      25771     0   20791170     0
     35167     0   29173014      33945     0   28904867     0
     33282   370   27478393      32140     0   27297079     0
     29738     0   23859586      28464     0   23524984     0
     38456   598   31559055      36881     0   31313396     0
     34738     0   28088584      33247     0   27743827     0
     38193   648   30854513      36657     0   30556948     0


A snmpwalk makes it a bit worse but not much. I already have packet loss
if bsnmpd is just started without any walks.

Regards,
Thomas