MKLAB

multicast ip’s are : 224.0.0.5 and 224.0.0.6
uses IP protocol 89
External routes are defined as routes which were distributed in OSPF from another routing protocol

backbone area - area 0, the core of the OSPF network, all other areas need to connect to it, is responsable for distributing routing information to non backbone areas, must be contigous, can be contigious through virtual links
Stub area - does not receive external routes, stub areas typically need to rely on a default route to send traffic to routes outside the present domain
Totally Stub areas - (TSA)like stub areas but they do not get summary routes as well, inter-area routes are not summarized in totally stubby areas, default route is the only outside route advertised and it is a type -3 LSA

ABR - Area Border Router - connects one or more areas to the main backbone network, is a member of all areas it is connected too
ASBR - Autonomous System Boundary Router - A router that is connected to more the one autonomous system and exchanges routing info with routers of those other autonomous systems, Run typically when BGP is used on a site.
IR - Internal Router - only as OSPF adjacencies with routers in the same area
DR - Designated Router - the router elected to maintain a complete topology table of the network and send updates to other routers via multicast,
BDR - Backup Designated Router - The router that becomes the DR if the original DR fails or has a problem, has the second highest priority

http://www.geocities.com/Heartland/4394/work/ospf.html
http://www.ietf.org/html.charters/ospf-charter.html
http://en.wikipedia.org/wiki/Open_Shortest_Path_First
http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/ospf.htm
http://www.cisco.com/warp/public/104/1.html