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<== Date ==> <== Thread ==>

Subject: Re: network problem w/ ioc
From: Maren Purves <m.purves@jach.hawaii.edu>
To: "Dale L. Brewe" <brewe@pnc.aps.anl.gov>
Cc: Chip Watson <Chip.Watson@jlab.org>, tech-talk@aps.anl.gov
Date: Wed, 25 Aug 1999 08:14:42 -1000
Dale,

yes, the routers could act differently depending on how they are/were 
programmed. We don't use "routeAdd" as long as we stay on the same 
subnet. I just looked up an old startup file where the ioc (temporarily, 
we were still testing then) was on a different subnet than the devices 
it was connected to, and in that case we used a routeAdd that had the 
router's address and the subnet specified.
My understanding is that a routeAdd "0" , "x.x.x.x" tells the router 
that all traffic is going "out" (and the programming of the router
decides whether "out" really means "out" or not).

Maren Purves


Dale L. Brewe wrote:
> 
> Chip
> Well, something along these lines seems plausible, I guess, altho the
> gateway has not changed, nor have the ioc parameters. However, these
> problems surfaced a few days after a new main switch/router was installed.
> Clearly the problem seems to be at a pretty basic level, as I have troubles
> pinging the ioc with no CA clients running. I haven't found anything that
> looks bad in either hardware or software. In the  ioc startup, I have
> routeAdd "0", "x.x.x.x"  for our subnet gateway. Is this correct? It worked
> before, but could the routers be acting differently for some reason?
> Dale
> At 08:08 AM 8/25/99 , Chip Watson wrote:
> >Dale,
> >
> >Your problem is similar to one I tracked down at PSI. If you
> >have a gateway (default routing node) improperly set in the
> >boot parameters of the IOC, then the following scenario can
> >happen:
> >
> >(1) the first client connects, but the ioc sends all traffic for
> >that client through the gateway
> >
> >(2) the gateway eventually sends a message to the ioc telling it
> >what the correct ethernet address for that host is (it doesn't want
> >to carry traffic unnecessarily)
> >
> >(3) the ioc mistakenly updates the gateway address instead of
> >installing an explicit host entry
> >
> >(4) the second client connects, and the ioc attempts to route
> >all traffic through the gateway again, but now it uses the
> >"updated" address for the gateway, which is client one
> >
> >(5) client one refuses to forward the packets (lazy, huh?), so
> >the ioc appears to drop off the net for everyone except the
> >first client to have connected
> >
> >Log into the ioc via the console if you can, and you can watch
> >this scenario play out.  Then, check your boot parameters and
> >either fix or remove the gateway entry.
> >
> >Chip


Replies:
Re: network problem w/ ioc Dale L. Brewe
RE: network problem w/ ioc Jeff Hill
References:
network problem w/ ioc Dale L. Brewe
Re: network problem w/ ioc Dale L. Brewe

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