6500 Etherchannel 10Gb card question

[dan_wiebell]

Scenario - 6509 connected via multiple etherchannels to a number of 3560s, 3750s and 3120s. I changed the etherchannel load-balancing algorithm, at which point the ports that were members of the etherchannel to the 3750Es all dropped out, but none of the other etherchannels were affected. The 3750Es are connected to a 10Gbps line card, whereas all the others are on 1Gbps line cards.

Is there any reason the 10Gbps line card should behave differently to the 1Gbps line cards for etherchannel?

Details of 6509:

NAME: "WS-C6509-E", DESCR: "Cisco Systems Catalyst 6500 9-slot Chassis System"

NAME: "WS-F6K-PFC3B Policy Feature Card 3 sub-module of 5", DESCR: "WS-F6K-PFC3B Policy Feature Card 3 Rev. 2.3"

NAME: "5", DESCR: "WS-SUP720-3B 2 ports Supervisor Engine 720 Rev. 5.4"

NAME: "2", DESCR: "WS-X6748-GE-TX CEF720 48 port 10/100/1000mb Ethernet Rev. 2.6"

NAME: "8", DESCR: "WS-X6708-10GE CEF720 8 port 10GE with DFC Rev. 1.6"

System image file is "disk0:s72033-ipservicesk9_wan-mz.122-33.SXI5.bin"

[kapathak]

Hi Dan,

When the members dropped out, did you have to intervene to make them join the port-channel again or did they automatically rejoin?

Also, anything interesting recoreded in the logs during that event?

Regards,

Kapil

[dan_wiebell]

Nothing unusual - the ports physically go down, then come back roughly one minute later. The etherchannel also goes down (which I suppose is entirely expected since the ports go down), then is restored when the ports return. There are no tracebacks or unexpected log entries. For all intents and purposes it looks in the logs as if someone had unplugged all the cables then reconnected them a short while later.

[kapathak]

Looks like a TAC case has been opened for this :-)

[kapathak]

Hi Dan,

Looks like this is an expected behavior on linecards with DFC daughter boards.

--snip--

If you change the load-balancing method, EtherChannel ports on DFC-equipped switching modules or on an active supervisor engine in a dual supervisor engine configuration will flap.

--snip--

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/channel.html

[dan_wiebell]

Correct - I had the TAC case raised and this was the answer.

[kapathak]

Please mark the case as resolved if this has answered your query :-)