Monday, 15 December 2008

Study Update 15/12/08

As you can probably tell from the lack of posts the studying has not been going very well as late. Work was previously taking it's toll with every piece of work being rushed in before the Christmas change freeze but now things are slowing down a bit in work due to the freeze and the fact that things generally slow down at Christmas. However the family commitments tend to pick up at this time of year so it does not look like I will get much more free time in fact family commitments tend to be even harsher than work commitments. To tell you the truth I have not been helping myself very much as I have been spending a lot of the time I should be reading the Cisco documentation browsing the web for presents or reading up on the current financial crisis and agonizing over whether it really is a good idea to buy that many presents this Christmas.

I have been plugging away at a few mini labs from Narbik's Advanced Technology Workbooks. (whoops I think I was so busy that I forgot to mention that I bought these in November just before the pound plummeted to much.) The workbooks are really good (I promise once I am through them I will compare them with the Internetwork Expert and the IPExpert workbooks) although I am taking my time getting through them. I am using Dynamips to run the workbooks so I have a topology that seems to work for the moment. I am still going through the OSPF section so I have not made great progress but I am repeating several of the mini labs to see if I can understand them a bit better.

The plan is to try and finish the OSPF section before my Christmas holiday in a weeks time and then start up again in the new year. Also I hope to get some time to setup the IPExpert Dynamips topology for my different machines, and if I get any free time over Christmas the plan it to at least hit the CCIE Command Memorizer to ensure I retain a bit of knowledge over the festive season.

In case I do not get a chance to post again best wishes to you and your families where ever you are in the world over the holiday season.

Tuesday, 9 December 2008

Commands: ispf

Looking through OSPF I came across a command I did not know about before. The command I came across was ispf, which stands for incremental shortest path first. The benefits of ispf can best be summed up from Cisco's own page on the topic.

OSPF uses Dijkstra's SPF algorithm to compute the shortest path tree (SPT). During the computation of the SPT, the shortest path to each node is discovered. The topology tree is used to populate the routing table with routes to IP networks. When changes to a Type-1 or Type-2 link-state advertisement (LSA) occur in an area, the entire SPT is recomputed. In many cases, the entire SPT need not be recomputed because most of the tree remains unchanged. Incremental SPF allows the system to recompute only the affected part of the tree. Recomputing only a portion of the tree rather than the entire tree results in faster OSPF convergence and saves CPU resources. Note that if the change to a Type-1 or Type-2 LSA occurs in the calculating router itself, then the full SPT is performed.

Incremental SPF is scheduled in the same way as the full SPF. Routers enabled with incremental SPF and routers not enabled with incremental SPF can function in the same internetwork.

Looks like quite a useful command to remember, so I will be adding it to my configs in future.

IPExpert Dynamips Configs

IPExpert have finally released their Dynamips configs. I have just downloaded mine from the members site so hopefully will get a chance to do a bit more labbing then I have been the last few weeks. It looks like they have 15 routers in the topology so it might be a bit difficult for me to get it all to run successfully on one PC but I will give it a go. Anyhow if you have not downloaded your files you can get them from your Internetwork Expert members page.

Wednesday, 3 December 2008

IPExpert Announcement Arrives

IPExpert's eagerly awaited announcement finally turned up in my inbox tonight. The main news I was interested in was the everything IE beta and the support for Dynamips. I have emailed IPExpert quite a few times in the past asking when they would introduce support for Dynamips and I was always knocked back saying it was not a Cisco supported product. So I was very happy when I saw that they were finally going to support Dynamips with their products. I was even happier when I read the announcement and found out that existing customers would get the .net topology file for free, click here for the official announcement. Oh and if you want to read the complete official announcement click here.