File Transfer Speeds

[dfrohman]

We have five switches in our network. (1) 3550, (1) 3750 and (3) 2950T. If we plug into the 3550 or one of the 2950T we can sustain file transfer speeds at wire speed (100MB/sec). If we plug into the 3750 or one of the other two 2950T switches we can only achieve file transfer speeds of 200KB/sec. There is no QOS in place. We are using PVST. Any ideas? If more information is needed please let me know.

[lgijssel]

Please check all links for duplex mismatches.

This kind of very slow response is typically caused by a link somewhere in the path where one side is at full duplex and the other side is only running half duplex.

Good hunting!

Leo

[dfrohman]

Both sides show 100Mb/s Full-Duplex

[glen.grant]

Seeing any kind of line errors on either side of the link ?

[dfrohman]

No errors what so ever.

[glen.grant]

Are these all starred off the 3550? The only thing would be to compare line for line the 2950 that works to the one that doesn't work and see if anything catches your eye . Are they all on the same subnet or are they being routed off to another destination when you are doing the file transfers ?

[dfrohman]

They are all connected to the 3550 as well as the 3750.

The only difference is on the one that works duples is set to auto, on the other two duplex is set to full. Cable was tested. They are all trunk ports carrying multiple vlans to the 3550/3750.

[glen.grant]

You say the other is set as full, is this on the 3750 ? If so the 2950's would need to be set as full also. Best bet is to set both ends as auto for speed and duplex , autonegotiate generally works pretty reliably between cisco devices now .

[dfrohman]

Did this and performance was the same. We also tried setting the switch and servers to 100/FULL and performanced actually decreased.

[anand]

I hope Jumbo frames might be enabled in 3750. once if the jumbo frames are enabled it affects all the ports & you cannot enable jumbo frames for individual ports. by default all 100Mbps NIC will supports only 1500Bytes,where as 1000Mbps NIC will support maximum of 9000Bytes, so probably jumbo frames might hav enabled in 3750, try disabling the jumbo frames & set to 1500 Bytes(requires restart).

[dfrohman]

Jumbo frames does not appear to be enabled

System MTU size is 1500 bytes

What is strange is one 2950 works great. Same IOS as the other 2950s