Microsoft email attachments over Frame Relay

[tduplantis]

Ok, hello everyone.. I have a very strange problem. Here are the details: Remote location in Corpus Christi connecting via frame relay to servers in Houma, LA. Corpus location has a 2620 Cisco with internal CSU/DSU. Here in Houma we have a 3620 with an external Adtran TSU, both routers are routing ospf. We have an pop3 server here in Houma that all of our remote locations connect to. Corpus is the only location that can't send Microsoft attachments, sometimes it works, sometimes it don't. They seem to be able to send any other type of file that isn't an .xls, .doc, or .mdb. They can zip up their microsoft attachments and send them. Here is what I have isolated so far:

1. Not their workstations, they can take a laptop to another location connected via frame and send attachments all day. Once they get back to Corpus, they have the problem again.

2. Not the server, we have about 250 people connecting to the same domain on the server and can send any type of email attachments.

3. There is no size limit on attachments for anyone, including the users in Corpus.

4. No router configuration anomonlies, on either side.

5. Virus? Don't think so, why would they be able to take the same pc somewhere else and have it work?

I'm totally stumped. Called Cisco, they said it isn't the routers. Called MCI, they say it isn't the circuit. I KNOW it isn't the pc's, or the server. We do have a PIX firewall, but that shouldn'g come into play on anything within our internal network, and I have checked the configuration anyway. Any entries that correspond to that particular location are no different than any of the other locations. What in the heck could cause this!!!

Thanks for you help,

Frustrated Network Administrator!

 

[wybnormal]

Well.. I would have to agree in princple with Cisco.. the routers really do not care a whit about the attachmemts.. it's just another TCP packet on the pipe. The frame is the same thing..

The PIX would be suspect or if ANY changes had been made to the routers like access-lists, IOS upgrades and so on. A sniffer would be a real help for this type of troubleshooting.. you could capture the actual datastream from the PC to the router and verify that it's at least getting there without out any errors. Are these folks running DHCP? if so, give one a static IP and info and see if that helps any. I'm assuming you have checked the counter in the router for any discards, que discards, other errors on EITHER the ethernet side or serial side?

Mike S
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin

 

[tduplantis]

Yes, I cleared the counters and had them try and send an attachment.. no errors. The router (10mb ethernet) in our main location had a few collisions, but they are normal on our network considering the traffic through that particular router. I also assigned a static IP, per your recommendation. That didn't work either. I guess I will find a contractor out there and let them sniff the local network. Thanks for your response.

 

[skelleywav]

I had a similar problem. It turned out to be some cheap NICs that came in some cheap clones. I swapped them with some 3COMs and it solved the problem. I hope the solution is as simple for you.

 

[tduplantis]

Well, this is even stranger... I had an engineer go out, unfortunately I had problems finding one with the ability to sniff, but regardless I got some good info from him. He was able to send any attachments other than Microsoft, even when it was a document saved from Word as a txt. If he saved a word document and saved it as a word document, then renamed it to a txt file, it wouldn't send. This was done multiple times. Now, it is definately limited it to ONLY microsoft attachments. Freaky.

 

[wybnormal]

Do you have any access lists? any UDP forwarding or IP helpers configured? MS likes to use multiple protocols even if you specify ONLY IP.. Look at a trace sometime how logging into the PDC looks like

I cant think of much that would block strictly MS attachments..

Mike S
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin