OSPF and EIGRP hello on serial link

Answered Question
Dec 20th, 2009
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Hi,

When OSPF is enabled on serial point-to-point link how hellos are sent to other end router? Are hello packets are sent as multicasts?

If yes what is the IP address as destination and source ( source - most likely IP address of serial interface )

To form a neighbor relationship intial hellos are to be received from neighbor and periodic hellos are requred to sustain the already formed

adjacency.  What are the IP address of the hellos after adjacency is established or is it the same? Is it so that once adjacency is established hellos are sent as unicast to other end of router?

In short


Case 1. OSPF  Hello packet - source IP and Destination IP while adjacency is getting established ?

Case 2. OSPF Hello packet - soiurce IP and Destination IP after adjacency is established?


On similar lines how hellos are sent in EIGRP case?


Please share the experience.

Thanks

Subodh

Correct Answer by paolo bevilacqua about 7 years 5 months ago

Hellos are always multicast unless you configure an explicit neighbor.

All this is explained in the documentation that I recommend you to read.

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Correct Answer
paolo bevilacqua Sun, 12/20/2009 - 06:13
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Hellos are always multicast unless you configure an explicit neighbor.

All this is explained in the documentation that I recommend you to read.

vinodsharma7 Sun, 12/20/2009 - 12:23
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hello,


Ospf destination address for all routers: 224.0.0.5

ospf destination address for DR/BDR: 224.0.0.5

Eigrp multicast address : 224.0.0.10



thanks

vinod

paolo bevilacqua Sun, 12/20/2009 - 12:38
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small typo, ospf dr is 224.0.0.6

Muhammad Anser Khan Mon, 12/21/2009 - 02:07
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Dear Subodh,


You can also see the multicast packets by the following debug commands:


#debug ip packet detail


#debug ip ospf hello


Regards,

Anser

Muhammad Anser Khan Mon, 12/21/2009 - 02:09
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Dear Subodh,


You can also see the multicast packets by the following debug commands:


#debug ip packet detail


#debug ip ospf hello


Regards,

Anser

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