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Nortel 8300 and slow performance after delay

We have two Nortel 8300's with split multi link trunking (I think I said that right) between them. Servers are plugged into both Nortel's and have either switch assisted load balancing or NFT.

There are other Nortel switches (55xx/3xxx series) which sit plugged into both core's. These have workgroup machines as well as machines that can only support a single NIC.

When I copy over 30GB of traffic from one machine to another on this setup, the initial 500MB or so is very quick, but then it drops down from around 250Mb/s to about 10Mb/s and stays that way. The server I am copying to becomes unresponsive from a network point of view, though the copy continues.

We have an old Cisco 6509 plugged into one of the 8300's. It appears that if I copy through a PC->Nortel 3xxx ->Nortel 8300->6509->server then I don't have this issue.

I am more in the role of end user in this scenario. I'm the one having the problem. Any suggestions on what to check? I've been working w/the network guy and we're looking at this, but nothing we've tried has helped.

Thanks!

Edwin

Reply to
edavid3001
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Hi Edwin

Do you set any filters on ERS8300 or ERS3510? Or, you can post the topology and configuration if you don't mind. It's too hard to know what makes this issue without log, configuration, or topology.

Reply to
Dophi

QoS and Filtering are turned off. These are overkill for our environment. We have three VLANs, #1, #2, #48, and #52 with almost everything on #1, a TV broadcast on #2, the split mlt on 48, and nothing on #52 but an empty port.

We did find one of the management cards in the 8300 negotiated to 100/ half. The other 8300 is at 100/full. So we're going to fix that, but I don't think that's the issue. there are 100k/s avg on that interface. Nothing else has a duplex mismatch. Everything is either

1000/full or 100/full in the core -- both at the switch and at the device.

More tests. Plugging my PC into the 6509 and copying the file to a server on the 6509 has the same results. However, plugging together using a cross over cable and the problem goes away.

Odd problem.

Reply to
edavid3001

I believe we've narrowed the problem down to old servers. The server's disk performance is very good up to a certain point, and then it goes to crap. If we turn on disk write caching, it's a little better. It's not the network, apparently.

Reply to
edavid3001

It's so weird. You didn't turn on disk caching and connect to two different end point on 8300 or 6509. How come you could get different test result? :S

Reply to
Dophi

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