From: Ian Stong (istong@stong.org)
Date: Sun Aug 07 2005 - 09:40:08 GMT-3
Have you tested a client locally connected to the same network as the
servers. If that worked then I would investigate the microwave link more.
If it doesn't work then it's a Microsuck problem.
If it works locally but not over the link the for your ping tests you should
run extended pings over the link and use various packet sizes as well as
different data patterns, with the DF bit not set and then set, etc.
Ian
www.ccie4u.com
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-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
chon_mon@nym.hush.com
Sent: Sunday, August 07, 2005 5:01 AM
To: ccielab@groupstudy.com
Subject: OT: Real world finger pointing at network
I have a simple issue with email. My exchange 5.5 clients and
servers communicate fine over a microwave link (building to
building) without issue. Everyone is happy with that. Recently,
the exchange server was upgraded to an AD 2003 clustered solution,
with updated clients as well. The upgrade did not go as planned,
and the finger is being pointed at the network as the problem.
Typically, I choose to go through the 7 layer model for
troubleshooting, however I am stuck with people who believe that
the MTU is the issue across the microwave link. So now, I am to
SPAN ports on each side to see the traffic coming and going with
large and small emails sent by the new outlook client.
I don't see the point to this, because what difference does it make
if its the old clients sending large and small emails, versus the
new test client sending large and small emails if they all have to
travel the same link between two routers, which don't distinguish
between different versions of Exchange (assuming, of course, no
access-lists or restrictions on traffic, etc.)? And if MTU was an
issue between buidlings, wouldn't that lead to other problems in
general? Don't Cisco routers fragment packets by default if they
are too big, and queue them?
There was a ping test, and it was successful in reachability to the
new clustered AD 2003 exchange IP address from across the microwave
link.
Now I can understand if packets are being sent across a link with
the DF bit set, and are dropped because they are larger than the
MTU size. However, I don't think Exchange sends packets with the
DF bit set.
Any input on this would be of help.
Server<----->Cisco router<----microwave---->Cisco router<-----
>Client
Thanks in advance.
-Sean
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