Re: Network Problems Big Time Update

[Gary L Peskin <garyp@xxxxxxxxxxxx>]

Guy --

Then why weren't you having these problems before the attack?  Were the
Cisco routers reconfigured or updated after the attack and was it new
router software that brought this problem to light?

Gary

> "Murphy, Guy" wrote:
> 
>         FYI...
>         The problem was subtle but we have a solution in place and it
> seems to be working.  It has to do with Ethernet hardware protocols.
> It seems that the Cisco routers may be having a problem with the 802.3
> protocol.  The AS/400 can and does recognize all of the protocols but
> when it communicates to the router, it's sends the 802.3 protocol
> packet last. Since this is the last handshake it sees, the router
> assigns 802.3 as the protocol to the AS/400.  This would be fine
> except that the router then seems to send packets to the AS/400 with
> conflicting information in them.  The AS/400 sees these packets as
> corrupt and discards them. This happens so frequently that the
> connection is eventually lost.   Other machines have not been affected
> either because they don't send 802.3 as the last handshake or they
> have a higher tolerance for bad packets.  The AS/400 is much more
> strict about what it will accept.
> 
>         We've reconfigured our Ethernet cards to recognize only
> Ethernet V2.  IBM reports that Cisco does have a patch for the problem
> and our campus networking people are contacting Cisco.
> 
>         I hope no one else is having problems like this but if you are
> then this may be of some help.
> 
> Guy Murphy - FACTS system
> University of Illinois
> 217-333-8670
+---
| This is the Midrange System Mailing List!
| To submit a new message, send your mail to MIDRANGE-L@midrange.com.
| To subscribe to this list send email to MIDRANGE-L-SUB@midrange.com.
| To unsubscribe from this list send email to MIDRANGE-L-UNSUB@midrange.com.
| Questions should be directed to the list owner/operator: david@midrange.com
+---