Paul Makepeace ;-)

April 21, 2005

Learning with humor

Posted in: Tech

In my quest to learn about redundant firewalls I've had to understand how Internet routing works. Another on my "vaguely understood for at least half a decade" list that's coming into much sharper focus. In the course of learning about HSRP, Hot Standby Router Protocol I discovered RouterGod, a series of articles on low-level internet arcana presented as... celebrity interviews! E.g. Paul Hogan tells us about HSRP! They are absolutely fantastic, especially 7 of 9 on OSPF

Once your OSPF routers have communicated with their neighbors, they begin to organize themselves into a military like hierarchy with routers occupying roles as Generals, Captains and Lieutenants. During this phase they are still weak. This is called "forming adjacencies". It is during this phase that you should rip your OSPF routers from their racks and beat them to death while you still have a chance.

In the next phase the OSPF routers will suddenly and without warning broadcast their message of doom to all other OSPF enabled routers. The OSPF Task Force calls this "Flooding Link State Advertisements". Once this occurs, every router knows what the entire battlefield looks like. Some people call this map of the battlefield a "link state database", but calling it an innocuous name does not make it any less threatening. Now they have knowledge, soon they will each run their Shortest Path First algorithm and they will posses intelligence. [...contd]

Crazy thing is, I've read half a dozen of them and remember almost all of it! Including never charge less than $1000 to set up HSRP and always get the money up front, before your customer sees that you fully configured HSRP on 2 routers in less than 5 min! #.

Posted by Paul Makepeace at April 21, 2005 18:51 | TrackBack

OSPF can be a canker to a network.
While working at a large ISP the fully meshed routers (using OSPF) decided to tell each other that the shortes path to anywhere was through themselves. So there we had it, a mesh of routers all telling each other "Psst.. the fastest route to anywhere outside of is via, pass it on"

Always check that SPF rule..

Possibly the worst day of my life.....

Posted by: bob.smith at August 2, 2005 09:36
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