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Pause Frames in 2950-LRE

Hello experts,

I have an eight port 2950 Long Range Ethernet switch, model WS-C2950ST-8-LRE, with sw image c2950lre-i6l2q4-mz.121-22.EA5a.bin. I have CPE585 on the other end of the lre link. The distance is about 250 meters. When I issue the command,

sh controller ethernet-controller, I see the following on one of the lre ports (this is a partial output, it details on all the lre ports).

LRE Enet Stats on Switch:

Transmit

1971984524 Bytes

176387421 Frames

14274008 Pause frames

Can somebody please tell me what does the Pause frame mean? Why am I seeing these? How can I eliminate this pause frame?

The applications (especially MS Project) running on PCs on the other side connected to the CPE have very slow response time. Some of them time out due to slow response time.

I have rate selection sequence LRE-SEQ-COMPLETE-REACH and profile LRE-15LL for each of the LRE port. Is there anything else that I can do to improve the performance and get rid of the pause frames? Thank you for your assistance.

Murali.

2 REPLIES
Bronze

Re: Pause Frames in 2950-LRE

Pause frames are actually a pretty decent concept for ethernet but hasnt really stepped into the data world. Usually pause frames are generated from transport kit e.g. Nortel Gig links, Cienna Ethernet links. What it does is if you have two systems compatible with the Pause concept then it is identical to becns in frame relay. The transmitter receives a pause which tells it to stop sending so much data so it backs off from transmitting and starts buffering more on the output. I turned that feature off on the Nortel kit which was attached to Cisco devices as it was just a total waste of effort in my case.

Community Member

Re: Pause Frames in 2950-LRE

Thanks for the reply. In my case, the lre sits between two 2950T switches, i.e., uplink via g0/1 port and downlink via an etherchannel with CPE 585 on the other end (2 lre ports connecting to two fast ethernet ports on 2950T). I am not sure what setting I should use and where to turn off this feature. Or is this normal on an LRE switch where the uplink is a faster link and the downlink is a slower link (according to the profile on the lre links, I should be getting 18 MB transmit and 16.67 MB uplink on each of the lre link of the etherchannel).

Looks like it is not a bandwidth issue because the Ciscoview shows the utilization on the interface to be less than 10%. It has to be something to do with latency or other feature on the lre that I am not aware of.

Any suggestion is greatly appreciated. Thanks.

Murali.

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