Monday, July 28, 2008

Dead Weekend + Switching Video

Last weekend was not very "usefull" to study... I´ve started working on friday at 08:00am, till saturday 09:00am, that plus travel time from home-work, work-home is more than 28hours straight! So I pretty much spent my saturday sleeping... When I finally woke up, with a terrible headache (anyone want to guess why?!), my wife had this "dinner" plan with a couple friends, so, well... I couldn´t say no... We went out. It was fun... but we came back home a little late, so I woke up late on sunday (again)!

Couple house things to solve, shower to replace, get something to eat, and that´s it, almost 07:00pm, and no study! Oh my! So I sit in front of my computer and started watching IPExpert CCIE R&S BLS Switching Videos. As usual I got impressed! The quality of the material is unquestionable, those videos are AWESOME!!!! Again, you feel like you´re in class! Cool! :)

Very good stuff in the video, one point was, a lab tip, for instance if you need to configure something that will take a few lines to do it, but the lab asks you to configure it using JUST ONE command, well, it seens weird, but possible if you have a pre-defined macro in the switch (that is already there, not one that you create!), use the command show parser macro to check if there are any pre-defined macros in the switch, so, you may be able to do it just applying the macro itself!

Also, anytime you see a topology with a Switch in VTP Transparent mode in the middle (like VTP Server  <--> VTP Transparent <--> VTP Server) be affraid. The VTP Transparent Switch will forward the updates between the other two switches, but, if, for instance you "prune" a vlan, that can cause us some problems! If the VTP Transparent switch doesn´t have this VLAN (or, if the VLAN is inactive) no matter if your VTP Server switches are using it or not, this VLAN will get pruned (in the VTP Transparent switch), and that can create some issues in our lab. Off course, we can solve this issue in a couple different ways, like removing those specific VLANs from the "pruning", for this  use the command  switchport trunk pruning vlan remove <VLAN List>

Another way to solve this is just create the VLANs in the VTP Transparent Switch, and activate them! Use the command vlan <vlan number> state active if you want to active the VLAN with no ports assigned! It´ll all depend on your lab restrictions and requirements!

It also talk about MST, and give us some good "insights" to avoid problems in the LAB itself, check this example configuration:

  • Enable MST
    • (config)#spanning-tree mode mst
  • Configure MST
    • (config)#spanning-tree mst configuration
      • Name (tree-name)
      • Instance 1 vlan (#-#-#)
      • Instance 2 vlan (#-#-#)
      • etc

This example is creating 2 MST instances, but, in fact your switch will be running 3 MST instances (do not forget about the MST Instance 0, it´s always there), so if your lab asks to have just 2 instances in your switch, well, that will force us to create just one new MST Instance and put all VLANs inside it! ;)

There are many, many other really usefull stuff and explanations! I´ll try to work on some really nice examples regarding Macros that is also in the Video!!! Wait and see!

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