Chassis /FEX Discovery policy

[Dragomir]

I am looking at the global policies and noticed that I have my Chassis/FEX Policy set to only 1link and link group preference to None

Should it be set to port channel instead?

I am current using 4 ports out of the 2208xp to the 6248up as server ports

thanks

[Walter Dey · Accepted solution]

It is best practise to configure port-channel between IOM and FI; be aware, that this is only supported for FI 62xx and IOM 220x.

Without a pc, a chassis discovery policy set to 1 means, that at minimum 1 link must exist; if you had 4 links wired up, only link came up; it was necessary to a chassis ack to bring the remaining 3 links up; and this chassis ack disrupts any traffic for about 20-40 seconds (no server reboot !)

[Dragomir]

is there any issue with changing the chassis/fex discovery polciy from 1 link and linking group preference none to 

4 link port channel? will it reboot the FI?

[Keny Perez]

Not at all... Chassis Discovery Policy will just affect how new IOMs are discovered and Link Group will just define how FI-to-IOM links will behave...

-Kenny

[Dragomir]

ok thanks. what should i be choosing for action link? 1,2,4, or 8?

[Keny Perez]

Tony,  what you choose depends on what you want...  I, personally, rather have only 1-link and reack a chassis cause in that way I am sure that if I add a new IOM to the chassis it will be discovered and I will then just need to reack the chassis...  But if in the other hand you want to ensure that, whichever IOM added to your chassis has at least, let´s say 20Gbps, then I would choose 2-Link... I hope I made my point :)

-Rate ALL helpful answers

Kenny

[Dragomir]

yes that makes sense. thanks

[Keny Perez]

sure, anytime Tony

[Keny Perez · Accepted solution]

Walter is totally right with the statement made... Just one thing to add is that if you add 2nd gen adapters to your servers, a Port Channel is created from the server´s adapter.  In other words, having 2nd gen adapters + 2nd Gen IOMs + 2nd Gen FIs and vPC/VSS, you have a huge PC from the servers to the upstream switches 

-Kenny