Giant packet on the 6513 EtherChannel

[cjrchoi11]

I configured EtherChannel between 6513 switches with three ports bundle and have a question for a giant packet.

--> 6513, SUP720, Native IOS, 12.2(17a)SX1

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File copy between servers which connected Server1 to 6513#1 and Server2 to 6513#2. there are many giant and received error on the EtherChannel ports even nothing on the server connected interface. I think this cause of overhead by the EtherChannel.

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Since I configure "system jumbo" globally and "mtu 9216" on the EtherChannel ports, no more received error but still increasing the giant packet.

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Looks the file copy working fine but not sure any non-visible issue(ex, performance,..)

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Can anybody explain my situation ?

Thanks,

[skarundi]

you are seeing a bug. bug id is CSCec62587.

Symptoms :

A Catalyst 6000 series switch running 12.2(14)SX or 12.2(17a)SX may report giants f

or packet size above 1496 bytes received tagged on a trunk over the sup720 ports.

The issue is cosmetic.

It is fixed in 12.2(17b)SXA.

[cjrchoi11]

No more giant on the EtherChannel port over the SUP720 since upgrade the 6513 SUP720 native IOS to 12.2(17d)SXB. it hits the bug CSCec62587 but still I have giant on the normal trunk port(not SUP720 port).

4006 and 6513(port g1/24) connected as trunk. nothing any kind of error(no giant also) on 4006 but increasing giant on 6513(g1/24) side.

My understanding is the rcv error accumulate all kinds of error include giant but the 6513 port only increasing giant and no other errors. pls correct me if I'm wrong.

SUP720 trunk port's giant resolved by IOS upgrade. Any idea on the normal trunk port's ? or idea to troubleshooting.

Thanks,

[#4]

A couple items to check. Did the Server lower the MTU size if a jumbo/giant frame was dropped by the switch? Some Servers retransmit frames that have been dropped with a lower MTU size. Like, a 576 size MTU. Make sure they aren't running the transfer with a lower MTU than is set on the port/interface. You can check with a trace on the server, sniffer, or Netstat. And, other points to check that might not be affected by the switch are retransmissions and windowing sizes.

[cjrchoi11]

The giant on the SUP720's trunk interface fixed by code upgrade to 12.2(17d)SXB --> CSCec62587.

But still I have giant on the WS-X6724-SFP module's trunk interface. nothing wrong in the sniffer trace. just increasing the giant(no rcv error increased). I suspect same sort of BUG as the above.

Any idea ?

[andy.steere]

This is a known issue (CSCed42859). It is cosmetic only. The CSE that had my TAC case says it will probably be a while before it is fixed.