IOM to FI Port channel failure clarification

[abdul basit]

Dear Members,

I have searched a lot but i am unable to find the exact information about the port channel from IOM to FI. In discreet mode of UCS, the uplinks role of 1 2 4 and 8 is clear and also if one link fail and the chassis is re acknowlege, the links are adjust to the power of 2. In port channel mode i do not understand,

Why is still there 1 2 4 and 8 links condition when the HIF interfaces are pined to port channel instead of individual links ?

Thanks and Best Regards.

Abdul

[Walter Dey]

Hi Abdul

Initial setup procedure:

Chassis discovery policy should be set to 1;

Wire up 2, 4 or 8 links between IOM and FI (4 is seen in many cases)

Create port-channel

ack the chassis (and since 2.2.4 this can be done per IOM in the chassis) resp per fabric/IOM in the chassis.

After that, there is no need for any chassis / IOM ack, even if links are failing.

Walter.

[abdul basit]

Hi Walter,

Thanks for your comment. I completely agree and understand what you said. What i don't understand is the 1 2 4 and 8 link condition for port channel case. In discreet case it is fine that the 8 blades can not be equally distribute. But why is this for the case of port channel where the load will equally distribute even if there are 3 links.

Thanks and Best Regards

Abdul

[Marcelo Morais]

Hi,

please take a look on this link.

Hope this helps.

[abdul basit]

Hi Marcelo, 

I have gone through this document and also some very good from UCSguru. I searched about it  a lot but still i am unable to find the answer to my question. 

Thanks and Best Regards

Abdul

[Walter Dey]

Hi Abdul

I believe there is a easy, non techncial answer.

1. Gen hardware didn't support port channel, and as you said, 1,2,4,8 links mapped to the 8 slot chassis makes sense.

with Gen 2 hardware, Cisco introduced port channel, which of course could support 1,2,3,4... links, as with any NX-OS switch platform.

However, UCS to be backwards compatible, required 1,2,4,8 links ! you could actually have a mixture of Gen 1 and Gen 2 IOM, with Gen FI and therefore port channel with Gen 2 IOM and discrete mapping with Gen 1.

Walter.

[Keny Perez]

1,2,4,8-link is the chassis discovery policy and it is meant to tell the system how many working cables/links need to be present to discover the IOM (this is a "per-IOM" policy and not the total of links between Chassis and FIs).

The "Discrete" and "Port-Channel" modes are meant to tell the system how those links will work, individually or in Port-Channel.

HTH,

-Kenny