Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!ncar!boulder!daemon
From: daly@cisco.com (Tom Daly)
Newsgroups: comp.dcom.sys.cisco
Subject: Re: cisco router 10baset (synoptics)
Message-ID: <26142@boulder.Colorado.EDU>
Date: 12 Sep 90 23:13:23 GMT
Sender: daemon@boulder.Colorado.EDU
Lines: 41

>> 
>> I received a message from pat@hprnd.hp.com.  It mentions 10baset incompatibility
>> and recommends not to attach cisco to synoptics.  Unfortunately, we does attach
>> all cisco to synoptics through ods.  Is it true?  If it is, how we can avoid
>> it.  Thanks.




Recently there has been some discussion on this list about
cisco's interoperability with various wiring concentrators
and/or Ethernet on twisted pair systems.  I would like to
clarify the situation:

cisco has many installations working and interoperates with
this equipment quite well in general.
There are some implementations of networks with repeaters which
violate 802.3 specifications by sending extra 'dribble' bits
at the end of a frame.  If these frames are received by a cisco
router, a framing error is (correctly) reported and the packet 
is dropped.

Since we found it easier for us to modify our microcode than for other 
vendors to correct their equipment, we have, starting with MCI 
microcode version 1.7 (which is currently shipping), modified 
our microcode to ignore framing errors.  This was done with the 
belief that it is better to allow interoperability in these cases, 
rather than enforce the 802.3 specifications.

To determine if this upgrade may be necessary, look for rapidly
incrementing frame input errors using the command "show interface ether xx", 
and examine the version of MCI firmware with "show controller mci".

If anyone believes that they are experiencing this problem, 
please contact customer-service@cisco.com to arrange for an upgrade.


Thomas Daly
Director, Hardware Engineering
cisco Systems, Inc.
daly@cisco.com