a2 is a very basic ospf assignment - due in 2 weeks

1. OSPF

Start off with a basic mesh of 4 routers, dexter/radia/tony/mrhorse.

1.1 implement basic ospf with a default route originating from dexter.
All routers are in area 0.  

	Show your default routing table at tony and dexter.  

	what are the important ospf commands for Cisco ospf?

	tony has two ways to dexter.  what command shows the ospf
		database and on tony what does that command show about
		how you might get to dexter?

1.2 tony has a next hop default route to dexter.  break the upstream
link on the next-hop router from tony's POV to the default route. 

	how long does convergence take?

	what if anything can you observe about how convergence
		was accomplished? 

1.3 hahaha has two ethernet links.  Figure out which link is associated
	with the physical cable for that link and that matches the 2nd
	i/f named xl1.  The IP address is 10.0.0.1.   (It is only
	needed to allow the tcpdump sniffer to work).

	You *may* move this cable to different ports on the routing/vlan/switch
	to watch traffic.

	Using # tcpdump -n -i xl1 try and capture the following packets

	note: tcpdump options -s <size> and -x (hex dump) allow you
	to get more data as tcpdump doesn't get all of the data, just
	the headers normally.

	1. an ospf hello

	2. an ospf LSA (what kind is it?)

1.4 put dexter and mrhorse in area 0, and radia and tony in area 1.
	Note: you also need to put radia's upstream interface in area 0.
	All of tony goes into area 1.  Look at the ospf database for all 4 routers?  What has changed
	from having them in the same area?

optional for extra gravy:

1. ospf can have a md5-based checksum authentication form.  How
is this implemented? 

2. design a multi-router ospf network using 3 areas.  put skynet and dexter
in area 0, and yakov in areas 1 and 2 (one interface per area).  Thus yakov is
a cross area router.  Put mandark and/or fenrir (don't need both of them) in
area 1.  Put radia/tony OR mrhorse in area 2.  dexter goes in area 2.
skynet goes in area 1.  Draw a text picture that shows your design.  

Now here's the tricky part.  Assume that mandark (or fenrir) is in area
1, and that you shutdown some upstream (towards area 0) interface
between mandark (or fenrir) and skynet in area 0.  How can yakov (and
the other routers) be manually configured so that mandark can still
reach area 0?