topic Re: Networking issue in Operating System - HP-UX

Networking issue

Jamal Al-Hammadi — Thu, 17 Aug 2006 05:09:10 GMT

Dear Support,
we have HP UX 11 and we are facing a problem with networking causing applications failure.
the problem is that HP UX cannot detect if another computer inside its SUBNET is turned off or not, if we tried to ping that computer while its off it doesnt reply AT ALL and it doesnt return "not reachable" or "time out" in the contrary it stays waiting while it PINGS that computer when its turned on.
are there any time-out parameters in HP ux for TCP communications. or should we do any other action?
your quick response is appreciated.
thank you,
Jamal Hammadi

Re: Networking issue

RAC_1 — Thu, 17 Aug 2006 05:17:43 GMT

Do as follows.

ping your_remote_host -n 3 ; echo $?
Base on return code, you can do what you want to.

Re: Networking issue

Peter Godron — Thu, 17 Aug 2006 05:19:51 GMT

Jamal,
man ping shows:
-n count The number of packets ping will transmit before
terminating. The -n is not needed if also specifying
packet-size. Range: zero to 2147483647. The default
is zero, in which case ping sends packets until
interrupted.

-m timeout Override the default timeout value (10 seconds) which
ping uses to timeout (in seconds) when a host or
network is unreachable. This option is valid only
with the -n option or when count is specified. The
-m option should not be used with count equal to 0.

The -m option is not effective for reachable hosts or
networks.

Re: Networking issue

rick jones — Thu, 17 Aug 2006 19:54:32 GMT

What RAC said :) HP-UX does not behave like Linux where it will cause ping to emit destination unreacable messages when the ARP resolution fails. It will just sit there dutifully trying until ^C or the -n limit is reached and set the return code.

On linux one cannot rely on the ARP timeout bit anyway for remote destinations.

And if there is something doing proxy-ARP, or if someone has hard-coded an ARP setting, the ARP timeouts won't happen for a powered-down local subnet system either, so even on Linux one should probably be using request limits.

Strictly speaking, ping is not TCP communications. ping is ICMP, which is below TCP.

Re: Networking issue

Steven E. Protter — Thu, 17 Aug 2006 20:23:46 GMT

Shalom Jamal,

This is the way things are with ping on many flavors of Unix/Linux.

On certain ISP based servers, an alias was created that made ping form the commands recommended above. This was done to prevent inexerienced users from clogging systems and support with questions.

As with many things, its left for the administrator to decide what the best practice is for their system.

SEP