Cross-Stack EtherChannel is Funky - why only available on low end switches?

Unanswered Question
Feb 20th, 2008

Hi,

I think the "Cross Stack" Etherchannel feature in the 3750 is awesome.

The ability to loadbalance a server across two switches and obtaining double the bandwidth too .... a truelly fab design for 'redundancy'.

Why is this not available on the 4948, or 4500s ... or even the flagship 6500s ?

I just purchased two 4948s and I am gutted.

Thank you

matt

I have this problem too.
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Edison Ortiz Wed, 02/20/2008 - 11:35

The stackwise technology allows multiple switches to become one logical switch. Once it's a logical switch, you can configure features such as 'cross-stack' etherchanneling.

The feature is now available in the 6500 VSS.

__

Edison.

Its even a little more than that. More like multiple switches become one physical switch. Especially with the non-E 3750s since they actually have to put a frame through the whole stack even if the destination port is on the same switch.

To the OP: That's because >1 interconnected 4948/4500 etc does not constitute a stack. They don't sync their mac tables/FIB/RIB, they each run their own instance of CDP, HTTP, SNMP and IP stack.

Joseph W. Doherty Wed, 02/20/2008 - 12:49

When you refer to 3750 cross stack etherchannels, you mean across members of the same stack, don't you? I don't think such multi 3750 etherchannels are supported otherwise.

I believe, the 6500 also supports etherchannels across line cards on the same chassis. (As Edison notes, also across two different 6500s when using VSS.)

Unfamiliar with 4500 chassis etherchannel capabilities.

Since the 4948 can not be stacked, likewise the 3560 series, they too don't support multi member etherchannels but likely the far side could connect with multi 3750 members in the same stack, multi 6500 line cards in the same chassis, or multi 6500 line cards in different 6500s connected via VSS.

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