MDS Port-channel with different fiber connection lenghts

[Luis Perez]

Hi experts

I want to confirm if i can establish a port-channel between 2 MDS 9396V using 4 ports each side.

A consideration to have in mind is that 2 interfaces have fibers with 7km lenght and the other 2 interfaces have fibers with 10km lenght. (Same mode E, same speed 32GB)

[marce1000]

   - FYI : https://www.cisco.com/c/en/us/td/docs/dcn/mds9000/sw/9x/configuration/interfaces/cisco-mds-9000-nx-os-interfaces-configuration-guide-9x/configuring_portchannels.html#wp7656457700
             https://www.cisco.com/c/en/us/td/docs/dcn/mds9000/sw/9x/configuration/interfaces/cisco-mds-9000-nx-os-interfaces-configuration-guide-9x/configuring_portchannels.html#wp3683799485

      In all circumstances , ==> must be tested before business operations are considered ,

 M.

[Luis Perez]

Thanks @marce1000 already checked the Configurating Port Channels section in the Interface Configuration Guide but not finding any related with the fiber lenght of the connections, so concluding it will be posible. 

Looking for any other documentation or anyone have tried tested that before to know about the behavior.  

[marce1000]

  - Make sure to not exceed the specified cable length according to the cable's specifications,

 M

[twigs]

Luis.

I have and environment where each fabric has 4 LW transceivers, 2 are for Trunking ISL-1 and 10Km and another two for the second Trunking-ISL and 20Km. In your case the maximum distance is 10Km, I think according to your LW-SFP, so @marce1000 advise to you about cable specification, this is important, and another factor mixing distances in the same ISL is the quality of the communications, in the past I had problems with this scenario, mixing 4 ISLs 2 with 8Km and another 2 with 10Km in one aggregate.

[Jason Mooney · Accepted solution]

My recommendation is to have 2 separate port-channels, Put the 7km distance links in one port-channel, and the 10km links in a different port-channel.  

Internally the MDS uses equal cost multipathing.  This means the ISL traffic will be distributed between both port-channels.

Having all four in a single port-channel can cause frames to arrive out of order, and this causes discards.

These are my personal responses and do not represent official guidance by Cisco Systems, Inc.