netisr HP-UX 10.20 top process slow network

[Steven Sobkowski]

Following a facility shutdown and replacement of the system backplane in an K220 running 10.20 we began experiencing slow network traffic on different stations running off of the system. The netisr process is consistently the top process running on the system, which I know is usually an indication of a possible network issue / application routing issue. The system backplane was replaced, as well as the NIC card on the system, but the slow network issues are still present.

All network settings on the system seem fine. Full Duplex 100 MB are confirmed both at the system and at the switch level.

Can anyone shed some light on the netisr and what might possible be causing these very strange and spuratic problems, or at least confirm for me that netisr is the symptom of a network / application / routing problem and not the actual cause of the problem?

Thanks a bunch.
Steve.
sobkowski@bellsouth.net

[Hoefnix · Accepted solution]

I had once a problem like this, then the HP engineer suggested to replace firmware on the NIC. It was strange because we had only moved the system 2 meters in the computer room and swapped cables. Then we had networkproblems that were fixed by HP by replacing firmware.(????)

HTH,

Peter

[rick jones]

(insert the usual song and dance about the OS being obsolete here :)

high CPU consumption by the netisr's is an indication of a high packet rate into the system. if individual connections seem slow it could be that packets are being lost.

if most of your traffic is TCP, start with netstat -p tcp (ftp://ftp.cup.hp.com/dist/networking/briefs/annotated_netstat.txt)

you can also check the landiag statistics and see if there are inbound drops - it is possible that packets are being dropped off the ipintrq. if so, you might be able to use nettune to increase the size of the ipintrq and that _might_ help (really dimm recollections here - not 100% certain nettune knows about ipintrq_max - or even if that is what the setting is called).

there may be some tunes in some old SPECweb96 benchmark results online at www.spec.org that have ipintrq tunings

[Steven Sobkowski]

Thanks. Turned out we needed the latest NIC card patches because of the fact that the system backplane was changed. This stopped the netisr processe from being the top processes. We were still experiencing inbound packet drops, which were minimized using nettune to increase the ipintr settings.

Great Feedback -- Thanks.