Kevin Dorrell, CCIE #20765

12 Feb 2008

NMC Lab 07 (and other things)

Filed under: General — dorreke @ 16:32

I fully intended to start Lab 07 yesterday (Monday) evening, but it was not to be.  I took my 11-year-old to his bass guitar lesson at 7 pm.  Usually that half-hour wait on a Monday is the ideal time to read a scenario.  The lobby of the Conservatoire de Musique de Luxembourg is a great place to read – something to do with its studious ambience.  This Monday my wife had given me something else to read connected with her own studies.  By the time I had done that there were only 10 minutes left to read my lab scenario.  Then home, and phone call from a member of the family, then dinner, then a discussion about Darwin and Wallace, and then it was too late to get started.

So, awake at 5:30 this morning, I decided to try and get an hour in the lab before work.  Romped through the Frame Relay section, remembering there was a constraint in the OSPF that impacted the FR DLCI choices.

Romped through the switch VLAN section – there does not seem to be much to this one.  Tested local connectivity on each VLAN … oh!  No connectivity.  Of course there is no connectivity dum-dum, you just shut down all the trunks between CAT1 and CAT 2 like they told you to.  OK, read ahead to the section on 3560.  There is a lot there, but basically you just make the connection through CAT3 and CAT4.  For now, I’ll just do the trunks so I can get the IGPs up and running.  I don’t have 3560s – my CAT3 and CAT4 are 2950s – but at least they can do this bit.

QoS on the 3550.  Looks a straight-forward WRR configuration with a priority queue.  Which is the priority queue?  It’s queue 4, just like the 2950 I am used to.  So wrr-bandwidth 40 33 27 0. No, it doesn’t work.  In the 2950, you define queue 4 as being the priority queue by giving it a 0 bandwidth.  In the 3550, you do so with the command priority-queue out, then give a dummy non-zero argument for its bandwidth.  In the 4500s I use at work, it is different again – the priority queue is queue 3, and you do tx-queue 3 and priority high.

I have just also remembered that VLAN 20 extends into CAT2 as an SVI.    Does that mean I have to extend the QoS all the way round that chain of switches? Anyway, how could I apply the QoS requirements to an SVI?  No, luckily it says only traffic to R2 and R3 should be affected, so the ports are all on CAT1.

After all that excitement, I forgot to map the CoS values into the queues.  I shall do that this evening if I have time after the cub scout meeting.

And that is as far as I got.  My reading ahead, for what little I did, has alerted me to some upcoming problems with OSPF.  They want me to extent area 0 into R3, which means a virtual-link.  Area 234 is NSSA, so the virtual link will have to go through area 20.  Why have they done that?  I bet there is going to be some issue about which ABR gets to translate the type-7 into type-5.  I managed to do a redistribution diagram and there don’t seem to be too many issues there provided I look out for Lo103 which gets redistrubuted into both EIGRP 30 and OSPF.

Time’s up!



  1. Kevin, your Darwin and Wallace discussion may not have been as off topic as you think. Within the context of a CCIE candidate it may well be very relevant – Natural Selection, only the strongest will survive, ability to adapt to changing blueprints, and change will inevitably happen (albeit over a prolonged period of time) Lesson learned: Patience

    Comment by Paul Carvill — 22 Feb 2008 @ 08:08

  2. Thanks for the comment Paul. Wallace and Darwin can teach us some interesting lessons – not so much about evolution but about scientific method and the role of the scientist. Why is it that everyone knows the name Darwin, but fewer people know about Wallace?

    Wallace was eventually rejected by the scientific community of time because he chose also to investigate subjects that were considered “unscientific”, such as spiritualism etc. He may have been trying to approach those subjects too with an objective scientific eye, but the fact that he chose to investigate them at all made him pariah to the scientific establishment. The establishment (and to a certain extent today’s establishment were made up largely of “internalists”, who view scientific work as valuable only in as much as it contributed to the direction of a notion of “progress”.

    It is interesting having a member of the family studying something “off topic”. The next step is to get her to look at BGP!

    Comment by dorreke — 22 Feb 2008 @ 12:38

RSS feed for comments on this post. TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Create a free website or blog at

%d bloggers like this: