Link Aggregation across cluster switches

[rvincenty]

Does a 4500G cluster support creating port groups using ports on different switches in a cluster ?

I want to have a host Ethernet connect to different switches for redundancy.

This message was edited by rvincenty on 10-8-09 @ 1:10 PM

[Fred_Mancen_1]

Hi.



No. The 4500G stacks or clusters don't supports distributed link-aggregation. A few weeks ago I faced the same problem when implementing 4500G stacks. I've tried to setup MSTP, it works well initially; but when one of the links is disconnected and then reconnected the stack doesn't converge, it lost connectivity and just after 30~40 seconds it came up again.



You can use link-aggregation connected straight to the master switch; this was the better way I found to provide resilience and stability to the stack.



Regards

[rvincenty]

What I am looking for is Link Aggregation for Hosts. Connecting each Ethernet port on different switches.

[Fred_Mancen_1]

Since the 4500G does nos support distributed link aggregation, you cannot connect links distributed in the stacked switches, even when connecting hosts.



Regards.

This message was edited by Fred_Mancen on 10-15-09 @ 1:56 PM

[aaguiar]

That is right, 4500G's master/slave stacking model wont support distributed link aggregation(DLA).



Since we are talking about servers, alternatively, you could bridge your two network cards(if we are talking Windows).



I believe gnu/Linux's bonding feature has an operational mode setting that wont rely on LACP and that is specifically used when there is no support from a switch. (its called balance-alb).

I can not predict what would happen if you used that mode on your stack.



Either way, it wouldnt be seen by the stack as single logical unit. =-z

[Michael_Stacks]

Can you tell me if the A5120's or A5500's support Distributed Link Aggregation?  I'm having a devil of a time finding clear specifications on them.  My thoughts are to connect the switches via an IRF/XRN link and use distributed link aggregation to connect to my ISCSI storage array.

[Fredrik Lönnman]

Yes, both A5120 and A5500 supports DLA.