Icnd2 ospf

alliasneo

I thought I would try and start a thread on everything I've been learning for the CCNA on OSPF.

So far I know that:

Hello and Dead Timers must match.
On a non-broadcast segment (such as serial interfaces and Frame-relay) you won't have a DR/BDR.
DR & BDR are elected on broadcast segments such as Ethernet.
Subnet masks much match for neighbor adjacencies.
Area 0 is backbone.
Updated are multicast to 224.0.0.5
Wildcard Masks are used in OSPF network statements.

......

MrXpert

NBMA Do elect DR/BDR but you must manually configure them

Point to point and point to multipoint do not elect DR/BDR

Hello timer and dead timers for point to point and broadcast are 10/40 seconds by default
Multipoint and NBMA are 30/120 seconds

Internal routers=a router which has all its OSPF enabled interfaces in one area apart from area 0
Area Border Router=a router which has an ospf enabled interface in area 0 and an interface in another area
ASBR=router which performs route injection/redistribution into OSPF area. These routers contain a connection to a seperate AS such as the internet.
All ABRs are Backbone routers but not all backbone routers are ABRs.
Some discussions amoung CCIEs say that backbone routers can be internal routers.

martell1000

all areas must be connected to area 0
DR and BDR election goes by priority, router id, highest loopback, highest physical interface
routers not elected DR or BDR are displayed as DROTHER (which can be quite confusing if you dont know what it means)
if there is just one router interface in a subnet ist automaticly gets DR
routers send their updates to the DR and the BDR using 224.0.0.6 which only these two listen to
DR and BDR send their updates out on 224.0.0.5
all routers execpt the DR and BDR reside in the "2WAY" state so dont be scared they are not stuck

Ltat42a

FF02::5 - IPv6 multicast transport address
FF02::6 - IPv6 DR multicast transport address

MrXpert

martell1000 wrote: »

are displayed as DROTHER (which can be quite confusing if you dont know what it means)

RUN FOR YOUR LIVES!!! THE DROTHERS ARE COMING!!! lol. Thats what I always think of when I see or hear that word. Sounds like some alien life form. I can imagine Worf saying things like "we must launch an attack on the Drother Homeworld, captain"
"The Drothers are a peaceful people, Commander, I seek to try negotiations first" - Captain Picard
Or if it was Ben Sisko "I'm going to blow them right out of the water and give them something to drother about"

Sorry i digress.:D