fcip link flapping priodically

Unanswered Question
Oct 2nd, 2007

We have a 9509 at the HQ site and a 9216 in the DR site connected via a DS3.

There are preiodic times when the fcip link will flap and come back up, sometimes it will continue for minutes and has happened for several hours with this error:

%PORT-5-IF_DOWN_TCP_MAX_RETRANSMIT: %$VSAN 50%$ Interface fcip1 is down(TCP conn. closed - retransmit failure)

originally the fcip profile was configured for 1000 max bandwidth and it was suggested to change it to something closer to the DS3 and this change was made:

fcip profile 1

ip address 10.1.2.1

tcp max-bandwidth-mbps 41 min-available-bandwidth-mbps 30 round-trip-time-ms 4

tcp send-buffer-size 5000

It made no difference at all. There is connectivity to the DR site during the flapping, I can see the bandwidth spike up, but there should be plenty to handle the load during the flapping.

Last night the serial interface of the DS3 was showing the tx load 65/255 and rx was 5/255 during the problem.

I am wondering, would the "min bandwidth" setting cause a "retransmit failure"?

That seems like more of a tcp/ip issue that an interface configuration issue, but I cannot find any reason for the flap.

No interface errors, but I have seen the ping response times go from 3ms to 25ms during this time, an indication of congestion somewhere.

Does anyone have any ideas?

There ar no errors on any of the interfaces for the DS3 or the fcip.

I have this problem too.
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sadbulali Mon, 10/08/2007 - 08:50

Try this, enabling ip compression, also change the Rx buffer to defaults 16, and disabled fccit.

wilson_1234_2 Mon, 10/08/2007 - 13:40

thanks for the reply,

Where do I make these changes and can you explain the logic behind them?

"enabling ip compression" I think compression is enabled in mode1 if I remember correctly

"and disabled fccit" what does this do?

"change the Rx buffer to defaults 16" is this in place of:

tcp send-buffer-size 5000

Are you talking about 16K rather than 5K?

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