Etherchannel through 3rd switch.

[martin.law]

I have a need to create a four-port Etherchannel between two Cat 6500 however two of the connections need to be presented transparently through a 3rd switch.

The reason for this is that the connections are fibre and I don't have enough SFP ports on one of the 6500. The plan is to use a 3750 effectivly as a media converter so the 2nd 6500 will see the Etherchannel on two fibre and two copper ports.

I need to know how to configure the 3750 to be transparrent to the 6500 whilst still retaining the integrity of the Etherchannel.

The is for a temporary solution so there is no option for increasing the number of SFP ports and the 6500s are in different buildings i.e. too far fro copper. The primary traffic type is iSCSI howver there are some 20 Vlans that need to be trunked.

Any thoughts would be appreciated.

[krahmani323 · Accepted solution]

Hello Martin,

I have never tested such configuration, but the idea woud be to configure Q-in-Q on the 3750 (In order for the pagp packets will be tunneled through the 3750).

The in and out interfaces of the 3750 would be defined as dot1q-tunnel with the correct options and recomendations => (l2protocol-tunnel point-to-point pagp ...).

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_58_se/configuration/guide/swtunnel.html#wp1005050

Best regards.

Karim

[martin.law]

Hi Karim

This looks like it is exactly what I was after. After reading the Cisco article I did a search and found another article which explains it very clearly.

http://blog.ipexpert.com/2010/07/12/etherchannel-over-dot1q-tunnels/

I will need to play arround with IOS versions and feature sets as I can find a switch that I have that cureently supports "

l2protocol-tunnel point-to-point".

Perfect answer, timely reesponse.

Thanks a lot

Martin

[Reza Sharifi]

Usually Etherchannl is formed between 2 devices that are directly connected together and not through a switch in the middle. I have never seen such a config.  You can however use a media converter to convert the SFP to copper and connected the copper to the second 6500.

Not sure exactly you need 1Gig or 10, but here is example of converting fiber to copper.

http://www.transition.com/TransitionNetworks/Products2/Family.aspx?Name=SGFEB1040-140-SGFEB4040-180&ProductID=33876

HTH

[martin.law]

Hi Reza

Already ruled out media converters as I am running single-core fibre full duplex (

1000Base-BX10).

L2 tunnel is the way to go.

Thanks anyway

Martin

[hobbe]

Hi

AFAIK this can not be done.

There is no way for the 3750 to be transparent in the way that you need.

The general way to fix this type of problem is to use a Media changer ie a small device that changes the media type from copper to fiber and vice verse.

Good luck

Hope This Helps