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Cisco Employee

Connecting L2 etherchannel to a L3 etherchannel


I have got a query on Etherchannels. Is it possible to make an L3 etherchannel on one side connected to the L2 etherchannel as a trunk on the otherside.

if so, Whatz the reqd configuration.

Any links with detailed config would be helpful.




Re: Connecting L2 etherchannel to a L3 etherchannel

Why would you want to do that , you can't route anything across if it doesn't match, not sure it would work anyway. If you need to route across it then create layer 3 SVI's on each side and then just create a layer 2 trunk/etherchannel and allow the required vlans across the trunk , this way it will still get routed.

Cisco Employee

Re: Connecting L2 etherchannel to a L3 etherchannel

This would be required in a case where Pure L2 switch is connected to a L3 router.

I am not able to establish a L2 PAgP portchannel with ISL trunking to an L3 port-channel.

I am able to establish L2-portchannel with Dot1q encapsulation but not ISL.

Re: Connecting L2 etherchannel to a L3 etherchannel

Yes this is possible. Recently we had to connect some Catalyst 6500's together physically using EtherChannels but logically routed links. Some of the Catalysts were Hybrid and some were Native so we had access ports on the Hybrid side with the Layer-3 being configured on the MSFC separately and routed ports on the Native side.

Everything worked although due to STP the Hybrid end took a little time to start forwarding. STP could be disabled on the particular VLAN though as long as you are sure it isn't on any other access ports.



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