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vAndrew
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Port Channel and LAGs

Can anyone shed any light on the configuration of LAGs and port channels?

We have configured port channels on cisco switches and created a vDS VMware end. Within the vDS we have created 2 LAG groups, one for each host within the LACP, however we can only set one of the LAGs as Active and the other can only be set to unused as anything else such as active, or standby gives an error saying not supported.

The current setup is 2 stacked cisco switches with separate channels for both ports using ports as follows:

Ports 1 and 2 (both switches) port channel 1

Ports 3 and 4 (both switches) port channel 2

Ports 5 and 6 (both switches) port channel 3

Ports 7 and 8 (both switches) port channel 4

2 LAG groups configured on a single vDS (maybe this is the problem?).

LAG group 1 contains all the ports from port channel 1

LAG group 2 contains all the ports from port channel 2

etc etc

The issue seems to be when vMotioning a VM the destination host doesnt have an active LAG, so cant communicate even though the port groups are configured (i believe) correctly.

So how are we meant to configure the LAG groups? One big group with ALL ports in and then set it as active? As obviously cant have 2 active LAGS, which then causes an issue?

If i create another vDS and add a LAG to that for one of the hosts, then that wont allow me to create the port groups with the same name, so that sort of defeats the purpose.

Any ideas, what am i doing wrong or any pointers for this. Maybe the one big channel is the way to do it?

-- Andrew (VMware VCP-DCV, MCSA)
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5mall5nail5
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The issue you're having is that you can only have one active LAG/port channel per vDS.

It would seem that you can configure multiple but only one can be active.

In order to utilize more than one LAG/port channel you need to create more vDS with dedicated uplinks/LAG per.

I guess more importantly it might be worth discussing the need for LAG/port channel.  Are you going for HA or are you trying to increase bandwidth?

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vAndrew
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Yeah i read that earlier about the single LAG per vDS, but then wondered why it lets you create more, especially if they are only able to be set as unused, seems a bit pointless.

If i create another vDS and add another LAG to it, then how does that work with the port groups as it wont allow them to have the same name, so wouldn't work, surely?

Sort of worked out why it doesnt work, but stuck trying to actually get a way to get it to work. Weve created a port channel per host for 4 NICs each, would we be better creating a single port channel for all the hosts and adding the NICs into that on the vDS?

Using it to increase bandwidth with a bit of redundancy included.

-- Andrew (VMware VCP-DCV, MCSA)
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vAndrew
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Ok so i backed all that out and created a single LAG group on a single vDS and added all the active uplinks to it, so 4 from each host and now its working. That still seems a bit odd to me, especially as there are only a maximum of 32 active adpaters allowed per LAG... which at the moment should be fine, but what about for expansion later down the line?

-- Andrew (VMware VCP-DCV, MCSA)
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vAndrew
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Just out of interest, what other way would be good if not using the port channels?

-- Andrew (VMware VCP-DCV, MCSA)
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