Hi there.
I'm wondering ospf advertising process.
R4 is DR and R5 and R6 area DRothers. there is no BDR.
as far as i know when some link changes occur in DRother, drother sends that change to DR using 224.0.0.6.
Finally DR relized there was change and send LSU to DRother using 224.0.0.5.
So i blocked that multicast 224.0.0.6 in R4's incomming inerface.
I thought since R4 doesn't recieved 224.0.0.6 from DRother, R4 doesn't know about that link change. and also doesn't advertise to other DRother.
But Still R4 recived that update and advertise to drother.
here is my configuration.
[R4]
int fa0/0
ip add 1.1.1.1 255.255.255.0
ip ospf priority 255
access-list 101 deny ospf any host 224.0.0.6 log (trying to block multicast from DRother)
access-list 101 permit ip any any
ip access-group 101 in
[R5]
int f0/0
ip add 1.1.1.2 255.255.255.0
ip ospf priority 0
[R6]
int f0/0
ip add 1.1.1.3 255.255.255.0
ip ospf priority 0
Neighbor status.
R4#sh ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
1.1.1.2 0 FULL/DROTHER 00:00:34 1.1.1.2 FastEthernet0/0
1.1.1.3 0 FULL/DROTHER 00:00:37 1.1.1.3 FastEthernet0/0
After configuring, I added Loopback interface and adversing on R5.
R5(config-if)#int lo0
R5(config-if)#ip add 5.5.5.5 255.255.255.0
R5(config-if)#ip ospf 1 area 0
I expected that R5 generate update using 224.0.0.6, but R4 block this 224.0.0.6 multicast. So R4 doesnt' know about that change and also doesn't advertise to R6
But Still R6 know that change.
Why R4 knows about that change even though i blocked 224.0.0.6 incomming multicast ?
access-list is working on R4
R4#sh access-lists
Extended IP access list 101
10 deny ospf any host 224.0.0.6 log (31 matches)
20 permit ip any any (429 matches)
Please correct me and explain and help me
Thanks in advance.
