Ether-channel cross switches

Got 2 Catalyst 4006 with Supervisor Engine III in redundant spanning-tree setup.

Now my systemsadministrator needs a ether-channel but to keep his servers redundant he would like to have the interfaces in each Catalyst but as same ether-channel.

Is this possible?

Reply to
Bjarke Andersen
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Nope, channels need to be on the same switch.

Reply to
Brian V

"Brian V" crashed Echelon writing news:3MqdnX3NQOqpt4zYnZ2dnUVZ

And when saying that you mean ether-channel in general og just this model of switch?

Reply to
Bjarke Andersen

Etherchannel in general. The only 'cross-switch' Etherchannel possible is to different members of a 3750-series switch stack.



Reply to
M.C. van den Bovenkamp


I believe that some end stations use "Etherchannel" to achieve resilient network connections in the case where there are two connections, one to each of two different switches.

No bundling actually occurs and the station uses only one link unless it has failed in which case it uses the other one.

The station configuration is identical to "Bundling" and the switches get no special configuration at all.

Very nice I say.

IIRC it was HP servers with Windows.

I have no idea what happens if you were to use say 4 connections, two to each switch.

formatting link
Assisted Load Balancing (SLB)

Seems to describe it.

The article tantalisingly says: "If automatic port trunking is required, 802.3ad Dynamic team type should be used with an IEEE 802.3ad Dynamic capable switch."

But does not describe the behaviour.

Reply to

Etherchannel is explicitly defined to be a link between 2 devices, with 2 or more links in the bundle.

This may happen if the device can run Etherchannel, but isnt operating the active protocol. If the switch end is not hard configred to use EC on the same switch, or the switch doesnt allow the selected ports to be part of the same bundle, then the bundle will not come up, and you have 2 or more separate links.

EC in "desirable"? mode is default AFAIR

There may be other ways to do this - EC is there to allow the device to use the same MAC on each port and distribute the load - you can "team" with different MAC addresses per port at least for outbound traffic (which is all you need on many server setups). - some of the microsoft teaming schemes can use a source multicast MAC address, and if you can force your switch(es) to work with that it sort of can be made to work, although you have to be careful about background traffic. - not many servers can keep a GigE port busy - so a lot of the time the load balancing aspects are irrelevant......

Again 802.1ad is defined to have 1 device at each end of the link set. the LACP protocol is part of teh standard to control the protocol and bring up the group.

The only kit i know of that can run a 802.1ad group split across 2 devices is some of the Nortel switches - main one i worked on was the passport 8600.

Reply to
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