There are two multicast addresses used for ospf routing.
22.214.171.124 used to send/receive hello packets among ospf routers.
If you have a network with DR/BDR the non DR routers send all their updates to 126.96.36.199 and then they get replicated to the others by sending it to 188.8.131.52.DR/BDR is only elected on broadcast/non broadcast network type.
In short these are the address OSPF uses in order to send Hello packets. These are not configurational parameters rather these are standard address used by OSPF protocol.
You could verify which address OSPF is sending the updated using "debug ip ospf events" as below
R1#debug ip ospf events
R1# *Mar 1 00:28:46.891: OSPF: Send hello to 184.108.40.206 area 0 on FastEthernet0/0 from 220.127.116.11 R1# *Mar 1 00:28:48.579: OSPF: Rcv hello from 18.104.22.168 area 0 from FastEthernet0/0 22.214.171.124 *Mar 1 00:28:48.583: OSPF: End of hello processing R1# *Mar 1 00:28:53.467: OSPF: Rcv hello from 126.96.36.199 area 0 from FastEthernet0/0 188.8.131.52 *Mar 1 00:28:53.471: OSPF: End of hello processing R1# *Mar 1 00:28:56.103: OSPF: Send hello to 184.108.40.206 area 0 on FastEthernet0/0 from 220.127.116.11
If the media of an OSPF interface is not broadcast-capable, OSPF traffic has to be send to unicast destinations, which have to be configured since the router cannot know them.
The advantage of Multicast is that the interface needs to send only 1 packet to reach multiple destinations of a multiaccess-network and there are no neighbor-statement needed; in other words: Automatic neighbor discovery.
Like the multicast addresses of other routing- and control-protocols, OSPF's AllSPFRouters and AllDRouters addresses belong to the Local Network Control Block 18.104.22.168/24:
[toc:faq]The ProblemOn traditional switches whenever we have a trunk
interface we use the VLAN tag to demultiplex the VLANs. The switch needs
to determine which MAC Address table to look in for a forwarding
decision. To do this we require the switch to do...
[toc:faq]Introduction:Netdr is a tool available on a RSP720, Sup720 or
Sup32 that allows one to capture packets on the RP or SP inband. The
netdr command can be used to capture both Tx and Rx packets in the
software switching path. This is not a substitut...
IntroductionOSPF, being a link-state protocol, allows for every router
in the network to know of every link and OSPF speaker in the entire
network. From this picture each router independently runs the Shortest
Path First (SPF) algorithm to determine the b...