Posted by: Richard @ | April 22, 2008

Week 15 Summary

Another week, another technology….

Study time:

Study Hours = 15.5  inc.
Lab Hours = 1

Total study time so far:
Total Study Hours = 186.5  inc.
Total Lab Hours = 17

What I have studied this week:
Serial Links and Protocols
Frame Relay

Recent test scores:
23/27 – WAN



Last week was a success; although I had to squeeze a few more hours into the week I completed ‘WAN’ without any hiccups.  I enjoyed working through the Frame Relay section because up until a few weeks ago I would consider myself a complete novice, I now think I have a good understanding of the technology.


I noticed a new version of Dynagen has been released recently; amongst other features such as the ability to emulate a PIX using built-in PEMU software I was very impressed by one particular feature à confDynagen has now been embedded into Dynagen, and what this means is that Dynagen now supports “Dynamic Configuration Mode” or in real-terms you now don’t have to ‘down’ your lab to make a topology change! J


A step-by-step example can be found below:

Step 1
Run the Dynamips Server and launch a .NET file

Step 2
Telnet/Console to each of the routers

Step 3
From the Dynagen DOS window enter Dynagen’s new ‘configuration mode’ using the command conf localhost  (localhost is where the Dynamips server is running)

Step 4
Navigate to the configuration level you wish to make changes at (refer to the .net file – e.g. router R1)

Step 5
Make the topology change by entering the same command you would do when building a .NET file (e.g. s1/1 = R2 s1/1 à i.e. connect R1’s Serial 1/1 interface to R2’s Serial 1/1 interface)

Step 6
Watch in amazement as your change takes place instantly (My example = a second link between R1 and R2 comes up)

no ‘.net config line’ also works!  Think of the interface as IOS for Dynagen à remember copy run start to write back your changes!



I’m now studying IP Multicast and I’ve made a really bad start!  I have gone to the effort of putting together a study plan and yet I didn’t consult it before starting IP Multicast – I ended up reading the wrong book; I spent over an hour reading the first multicasting chapter of RSCG2 when I should have been reading Routing TCP/IP V2! L  Never mind, I’m sure it wasn’t a complete waste of time.


I quickly put this together today to aid my memorization of IPv4 Multicast Address Space allocation:

Lastly, here is a link to a very interesting Cisco TAC case regarding BGP – K10794084 à that’s a ‘gotcha’ that I’ll be adding to my notes.

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 )

Twitter picture

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

Facebook photo

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

Google+ photo

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

Connecting to %s


%d bloggers like this: