10-10-2006 07:39 PM - edited 03-03-2019 02:18 PM
Hi, can you clarify this:
An exercise states:
"Imagine one of the WAN links on an OSPF
network has gone down, causing a topology
change. What's the reaction
to maintain route consistency
when OSPF notices a change in the
network ?
Answer: When a link changes state, a link-state advertisement (LSA) concerning that link (route)
is created by the device that detected the change and propagate to all neighboring devices using a special multicast address. This is
called flooding."
My question:
Does the Router which notices the link state change actually floods the network, or in reality the router sends the new LSA to the DR; then the DR would send out the LSA to all other routers in the network ? Thanks for your great help !
Solved! Go to Solution.
10-11-2006 10:06 AM
Yes, the LSA will be flooded out all OSPF interfaces on detecting link state change. One of the requirements of OSPF is all the routers within an OSPF area has to have an identical database.
HTH
Sundar
10-11-2006 02:05 AM
Hi marlon,
The DR & BDR are elected only in a multiaccess network to reduce the number of adjacencies to be formed.
So whenever there is a link state in a multiaccess network, the router would send the LSA to the ALLDRouters (224.0.0.6) which would then flood them to all its neighbor.
On the other hand if the network is not a Multiaccess network the LSA are flooded by using the multicast address of 224.0.0.5
HTH, rate if it does
Narayan
10-11-2006 06:02 AM
Very good observation about the Multiaccess vs NBMA environment.
In addition to the sending the LSA to ALLDRouters (224.0.0.6) upon link state change, doesn't the router also send the LSA to all its interfaces in order to notify adjancent routers ? Isn't that right ?
10-11-2006 10:06 AM
Yes, the LSA will be flooded out all OSPF interfaces on detecting link state change. One of the requirements of OSPF is all the routers within an OSPF area has to have an identical database.
HTH
Sundar
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