Drop packets on DS3 line

[tonyktone]

Hi all,

I have a DS3 line between two facility. The handoff from the local carrier is coaxial that goes to my 3Com S600 then ethernet over to the network...Same setup on both end.
For the past 3 weeks I have been having major issues with drop packets, also the line would drop totally. At the time of the drop packets there's no traffic going over the WAN. The drop could last up to 10 minutes at any time and is very sporatic as it happens anytime. I had the local carrier do a stress test which came back clean, I also check and rebooted all the network equipment...No errors.
I know I'm using 3COM equipment, and this is a Cisco thread. But the problem could be univeral.
I not seeing any errors on our network equipment that could indicate a problem.

This problem actually started when the local carrier came out to install additional data line, when they were out they actually dropped our DS3 line. But again the carrier is saying they show everything is clean on their end.

Any thoughts would be greatly appreciated, as I'm getting hammered by administration .

Thanks.

 

[jneiberger]

How is your clocking configured? Do you have one side configured to generate clocking and the other side configured to accept clocking from the line? I had a similar problem with a DS3 when I accidentally configured both sides to take clock from the line.

 

[tonyktone]

Hi,

Thanks for the input...Yes that was one of the first thing I checked, also the framing.
Everything checked fine on the Wan switch. When you had your problem was it sporatic, like every few hours or more continuous? Mine happens anything during the course of 24hrs, sometime up to 4 times a day. Also there's no pattern on the time to indicate a task or process is running at that particular time.

Any further inputs will be greatly appreciated.

 

[jneiberger]

My issue was sporadic. I had an entirely different issue on that same line a few weeks ago. We would see errors of varying ferocity and the line would drop from time to time. That turned out to be a bad cable upstream of our DS3 CSU/DSU. You might want to check your cable path, and have your provider check theirs.

 

[plshlpme]

how long of a test did you let the telco run?
it could still be a telco problem.

i would have them go out to both ends and do a real end to end test with bert testers...

if they can run clean for say 4 hours then youll have to look closer at your equipment...

 

[tonyktone]

Hi,

Thanks for the info...I did have the carrier come and did an end to end test for a little over 2 hours that came back clean.....I'm having a consultant come in with a sniffer for a couple of days to plug into our DS3 feed and see exactly what is going on.
Thanks for the info.

Any further info please let me know.
I will let you all know what ends up being the problem.

Thanks

 

[plshlpme]

do you see errors incrementing on the coax interfaces in the 3com equipment?

 

[tonyktone]

No,
I don't see any errors at all, which is totally weird. I'm starting look at possibly an application is causing the issue.
The problem tend to happen more during the course of the day, especially during peak time...in the morning, also in the afternoon. With very little problem over the weekend, and off hours.

 

[SloTCMS30]

We had the same problems with our DS-3 on AccuRing. We turned on 'scramble' and the problems ceased. Not sure this will help you, but it is worth a try because our was also clean to telco...