Default Router Trouble

[Nathan Sims]

It seems that my HP-UX machine doesn't like to stay connected to the net. Every 15 minutes or so it seems to fall off, and I have to delete the default router with route delete default then I have to re-add with route add. This seems to happen way more frequently than it should with a fresh install of hpux 11.00. Can someone help me pinpoint the issue here? I'd appreciate it very much. Thank you.

[harry d brown jr]

You could be experiencing many different problems, but some of the top would be lan-card issues, cable, router, OS network patches, etc... From the console, can you ping your router or other hosts on your sub-net? What kind of network services are you running (ie: arpd, named, nfs, gated...)?

[Nathan Sims]

Yes I can ping the router so long as it's in the mood to work. If i ping and it says unable to resolve name, I have to route delete default, then route add default and the connection comes back. The only service I'm running on it is nfs, nothing has changed. This is a brand new installation of HP-UX on a c180. It works for a while and then stops working.

[harry d brown jr]

Is it possible that you might have duplicate IP's or duplicate MAC's?

Are you using /etc/resolv.conf ?

[Nathan Sims]

I am using /etc/resolv.conf
It has the correct name server in there and everything. No I don't have duplicate IP's. The machine did not have this problem when it was running 10.20. Only after I installed 11.00 did this show up.

[Vincent Fleming]

1. Check it with linkloop
2. patch the system
3. check if ping works to the router's IP address so you don't attempt to resolve the name

It sounds like you need a patch to me, though. linkloop should help identify if you've got a network card problem or a software problem. My guess is that you'll find that it's a software problem and bringing the system up to current patch levels will fix it.

[Nathan Sims]

I was trying to get the Quality Patch Bundle for 11.00, Is this what you're referring too should I look for individual patches?

[Sanjay_6]

Hi Nathan,

If you are covered by HP software contract you can do a patch analysis on your system, create a patch budle and download directly from the hp web-site.

That is better than patching your system using the quaterly patch bundle.

Follow the link below to reach the customised patch bundle section on ITRC.

http://us-support.external.hp.com/wps/bin/doc.pl/sid=06a1af85135297982b

Hope this helps.

thanks

[Anthony deRito]

Nathan, my guess is that packets headed toward your default router are no longer routable using that particular hop. This is causing your default router to produce an ICMP redirect notifying your machine that it cannot deliver your packet to its destination any longer and that there may be another "better" route to use.

What does your routing table look like? Typically, you can easily identify a modified route when you see an "M" in the flag field of the route as follows:

# netstat -nr

default 204.104.63.30 UGM 42 3086056 lan0 1500

M means modified. This usually happens to dynamic routes. To be honest, I have never seen this happen to static routes but its a thought.

You can turn on logging on your router to check if ICMP redirects are being generated. If they are, you do have the option to turn it off on your router if its doing more harm than good.

Tony

[Nathan Sims]

Aha! Here's the fix for anyone who's interested.

HPUX 11.00 supports multiple gateways using route add. It will use default first and check to see if the default router is available by sending it a ping. If it doesn't get a reply, it will consider the route dead and move to the next gateway defined. If there are no other gateways defined then it will shut down all outbound traffic. The fix is to make sure that your router responds to ICMP requests or to run this command to turn probing off 'ndd -set /dev/ip ip_ire_gw_probe 0'
then add an entry in /etc/rc.conf.d/nddconf to turn the probing off at each reboot. Then re-add the route and everything works