3850 network modules - Beware when configuring

[lcotter]

Just a heads up for anyone contemplating a port channel  with gig ports gi 1/1/3 & 4 using the C3850-NM-2-10G module.

You actually need to configure the te 1/1/3 & 4 ports even though they will only use 1gig or else you may get a  loop event.

Intuitive it is not!

see http://blog.router-switch.com/2013/11/cisco-catalyst-3850-understanding-interface-configuration-on-nm-modules/

[Ton V Engelen]

We use the C3850-NM-2-10G

Yes, when using these modules you ll have to keep in mind that

Gi 1/1/1 and Gi 1/1/2 are the one Gig uplink interfaces

Te 1/1/3 and Te 1/1/4 are the ten Gig uplink interfaces

when configuring these interfaces

And yes, there are still Gi 1/1 3 and Gi 1/1/4 interfaces in the config, which are the right interfaces for the C3850-NM-4-1G module. 

So is depends on which module is used, which interfaces to configure. . 

[lcotter]

Indeed, Ton, you said it "keep it in mind" and the rest of it too.

We network engineers shouldn't be making simple logical assumptions about something that should be so straightforward :-)