IPexpert Volume 1 section 5 - L2 protocol tunneling

Not gonna say much here just that this teeny lab kicked my butt. I must say I fell pretty comfortable when it comes time do anything with BGP, OSPF, EIGRP and routing. Even multicast and IPv6 I feel comfortable now. QoS, I am getting there. I thought l2tunneling was cake until I started this lab. That was Sunday. Today is Wednesday and I finally hammered it out. Two online rack sessions and a bunch of researching in between. I didn't just follow the proctor guide on this!

I tried it my own way - didn't work.
Tried to fix it - didn't work.
Saved configs
I copied the final configs to the switches just to make sure the solution worked - it worked.
Recopied my configs over and progressed from their.

Repeat about a dozen times.

Troubleshooting, debugging, I learned a lot along the way.

I even found out a lot about how LACP works, by exchanging your mac and the partner mac - a lot like the OSPF adjacency INIT stage.

Also, the solution doesn't quite follow what you read in the DocCD, another reason it is good to get a taste of more than one vendor, because there are many ways of doing everything.

I swear I know this lab inside-out. It's got me searching for different scenarios. Hopefully come lab time, I am well prepared for anything.

Resolving precedence names to numbers

I had a task to configure WRED for all packets with the precedence of "routine" but doesn't give you the precedence number...so to find it I did this:

Rack1R1(config)#class-map TEST
Rack1R1(config-cmap)#match precedence ?
<0-7> Enter up to 4 precedence values separated by white-spaces
critical Match packets with critical precedence (5)
flash Match packets with flash precedence (3)
flash-override Match packets with flash override precedence (4)
immediate Match packets with immediate precedence (2)
internet Match packets with internetwork control precedence (6)
network Match packets with network control precedence (7)
priority Match packets with priority precedence (1)
routine Match packets with routine precedence (0)

Routine is 0!

Task Interpretation (probably part 1 of many)

Recently I had a task that told me a serial link between two routers will only be used if the Ethernet and frame-relay links between these routers went down. Detection of the failed links and convergence should happen within 10 seconds. Immediately I thought of the backup interface command, however:

R4(config)#interface e0/0
R4(config-if)#backup interface s0/1
Serial0/1 is already a backup for Serial0/0
R4(config-if)#

You can only have an interface be a backup for one interface!

What the task was really asking for was to make OSPF detect the failed neighbors within 10 seconds and thus install the direct serial link route. We do this by adjusting the hello-interval on the Ethernet and frame-relay links to 2 seconds (2 x 4 = 8 second dead interval).

Another reason it is important to think a little outside the box and try to understand what the goal of the task is.