[c-nsp] Nexus FEXs and pinning max-links

[Bielawa, Daniel Walter]

For our N5k/N2k implementation, we choose to have our servers use port channels (via vPC) to connect to the N2k, and to then have an outbound vPC from our N5k's, instead of a vPC connecting the N2k's. 

Thank You

Daniel Bielawa 
Network Engineer
Liberty University Network Services

(434)592-7987

LIBERTY UNIVERSITY
40 Years of Training Champions for Christ: 1971-2011

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of -Hammer-
Sent: Wednesday, February 15, 2012 9:53 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] Nexus FEXs and pinning max-links

All,
     I've been playing with some Nexus gear in our lab and I'm confused on a physical layer issue. When defining the FEX, you define the max-links. Originally I set it to four and then built my port channel. 
Of course, it gave me an error

ERROR: FEX max-links not configured to be one

Which after googling and thinking thru makes sense. I'm defining the ports as a port channel so I need a max-links of "one". Not "four" (as in four wires between the N5K and N2K). That makes sense. What I'm struggling with is in what scenario I would NOT create a port channel. 
When would I just assign the physical links to the FEX and not build an etherchannel for them? Anyone?


!!!get your FEX on

!!!! define a FEX

fex 101
     desc FEX101
     !!! define maximum links!
     !!! trick question! If the link is a PO then your max links is 1.
     pinning max-links 1

!!!! define the port channel
interf po101
     !!! MODE!
     switch mod fex-fabric
     !!! associate it with the logical FEX
     fex asso 101

!!!! Bring the physicals (with the FETs connected) into the PO101 interf ra e2/1 - 4
     !!! MODE!
     switch mode fex-fabric
     !!! call the fex!
     fex ass 101
     !!! call the PO
     channel-group 101
     no shut


-- 


-Hammer-

"I was a normal American nerd"
-Jack Herer


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