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LACP between Cisco/IBM Bladecenter Switch and Alcatel OS7700

Hi there,

we've got a problem with setting up an etherchannel between a Cisco Switch (built-in in a IBM Bladecenter) and a Alcatel OS7700. More specific, we do not have a problem to set it up - by verifying the channel status on both sides everything seems to be ok. See the attached drawing for details, how everything is connected. The problem is as follows: When a client in Subnet (behind a Cat4006) tries to ping a Server in Network, which is located in the Bladecenter behind the Alcatel Switch, it works for some servers, but not all. That means, for example, you are able to ping and .101, but not .102 and .103. When we use only one single Gig Link, everything works fine...of course.

So my first thought was, there must be a problem with the load-balancing algorithm. i found out, that the blade center switch does load-balancing by default with src-mac. The Alcatel Switch does src-dest-IP. So i changed to src-dst-ip on the bladecenter switch as well. But it still doesn't work correct. Now i'm able to ping, for example, the .100 and .102, but not .101 and .103.

When i issue a show lacp internal detail and show lacp neighbor detail, the only thing which _might_ be a problem is that the cisco switch says: "i request slow lacpdu's" and alcatel says "i request fast lacpdu's". As i'm not such detailed in LACP, i'm not sure if this might cause the problems.

When we try to set up that in our LAB (but with a 3750 instead of the blade center switch), everything seems to work fine :(

Has anyone experience with that blade-center switches and LACP? Or any clue/hint, what might cause the problems?




Re: LACP between Cisco/IBM Bladecenter Switch and Alcatel OS7700

LACP Timeout value from the partner and will adapt to either Slow or Fast LACPDUs (when receiving 'Partner_Oper_Port-state_LACP_Timeout' set to Long timeout).

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