Re: network problem w/ ioc

["Dale L. Brewe" <brewe@pnc.aps.anl.gov>]

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

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Dale L. Brewe     PNC-CAT/U. of Washington
 ph: 630 252 0582         fax: 630 252 0580
 Mail:
 Argonne National Laboratory/APS
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