This is the follow up discussion for the post titled, “Have you seen my Router ID?”... [Read the rest of this entry -->]
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Archive for the 'IGP' Category
In yesterday’s post, titled “Have you seen my Router ID?”, a challenge section was provided. This post will focus on scrutinizing the section itself, from a strategy / analysis point of view.... [Read the rest of this entry -->]
There is more than one possible solution for this challenge. Feel free to post your proposed answer in the comments section. We will try to keep comments hidden from public view, so that the fun isn’t spoiled for others. Also, don’t feel bad if the answer(s) aren’t immediately apparent. A number of very bright people have been puzzled by this scenario. Answers will be posted on Friday, September 18th.... [Read the rest of this entry -->]
The feature we are going to talk about today may look a bit convoluted, but it demonstrates core OSPF behavior: combining link-state and distance-vector behaviors. The command capability transit was introduced in IOS 12.3T and is on by default. However, the description is rather confusing and does not explain the underlying mechanics. We are going to give an in-depth look at this feature now.... [Read the rest of this entry -->]
We have added a lesson to the 10-day ATCOD on EIGRP for IPv6. This is a key CCIE R/S Version 4.x topic. Enjoy!... [Read the rest of this entry -->]
One of the most popular series on this blog site is the Redistribution series by Petr Lapukhov.... [Read the rest of this entry -->]
CCIE R/S Written Sample Question – Part 2
Posted in CCIE R&S, CCIE R&S Written, IGP, IP Routing on Aug 29th, 2009
If you are interested in Part 1 of this blog series – click here.... [Read the rest of this entry -->]
Intro
There was a lot of blogging related to OSPF topics recently. In this post, I would like to clarify some common misunderstandings that many people have about OSPF route filtering. I have seen so many folks (some of them really experienced persons!) incorrectly understanding the underlying behavior so it’s about time to make this clear. Oh, as a matter of fact, making “everything clear” is one of the primary goals of the new 5-Day Kickstart Bootcamp (ad here!) which targets in-depth technology explanations [Read the rest of this entry -->]
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OSPF Areas, Part 5, the Totally Not-So-Stubby Area
Posted in CCIE R&S, CCIE R&S Written, CCNA, IGP, IP Routing, IP Routing - NA Level on Aug 5th, 2009
As a former English Major at the University of Massachusetts, Amherst, I really loved the oxymoron. You remember those…”sharply dull” or “cruel kindness”. Well, the OSPF protocol has one whopper of an oxymoron in its special areas – The Totally, Not-So-Stubby area!... [Read the rest of this entry -->]
EIGRP is based on the concept of diffusing computations. When something changes in network topology, the routers that detect a loss of network prefix will send out EIGRP QUERY messages that propagate in circular waves similar to the ripples on water surface. Every queried router will in turn query its neighbors and so on, until all routers that knew about the prefix affected. After this, the expanding circle will start collapsing back with EIGRP REPLY messages. The maximum radius of that circle may be viewed as the query scope. From scalability standpoint, it is very important to know what conditions will limit the average query scope, as this directly impact the network stability. You may compare the “query scope” with the concept of flooding domain in OSPF or ISIS. However, in contrast with the link-state protocols, you are very flexible with chosing the query scope boundaries, which is a powerful feature of EIGRP. ... [Read the rest of this entry -->]
OSPF Areas, Part 4, the Not-So-Stubby Area
Posted in CCIE R&S, CCIE R&S Written, CCNA, IGP, IP Routing, IP Routing - NA Level on Jul 31st, 2009
Click here for Part 3 of the series.... [Read the rest of this entry -->]