Simple link upgrade from 1Gb to 10Gb,
SiteA Sw1 has a 1Gb link to Core
Sw2. We want to upgrade it to a 10Gb link.
Easy enough right? Just copy the
configs off ports G0/1 on the SiteA Sw1, and the Core Sw2
Then paste them on to ports
TenG0/24 on each Sw.
Unplug the fiber at both Sws,
and plug into the new ports.
(Now we did a lot of leg work before the upgrade.
We made sure the fiber was good and would support the TenGig
We installed the new optics)
So when we switched over the
fiber and the ports lit up,
We just know we were good-to-go.
Buy when we tested the link by
shutting down the port to Core Sw1.
…. Was all we got, no eigrp
routes, but I could see Core Sw2 with Show CDP neighbors.
Of course this is not good, and
I starting thinking what could be wrong.
A quick thinking colleague, said “passive-interface” and sure enough
because Site1 had
Access Layer ports so it was
using default passive interface under the EIGRP config.
Core Sw2 was not because it did
not have any Access Layer ports.
No default passive-interface
t0/24 on SiteA Sw1 worked like a charm.
!!!! All day long.
Just goes to show you how not
thinking about the big picture and a little command,
Can sneak up and bite you.
