I think UDP probably will have problem for multiple ospf instances implementation.

Thanks,
Jason

-----Original Message-----
From: Manral, Vishwas [mailto:VishwasMNETPLANE.COM]
Sent: Monday, February 18, 2002 5:35 AM
To: OSPFDISCUSS.MICROSOFT.COM
Subject: Re: OSPF over UDP .. why NOT!

Mareline,

OSPF running over IP, uses IP fragmentation and reassembly.

One disadvantage of running OSPF over UDP would be the additional UDP header
per packet(if that is what you meant by additional layer)which would be an
overhead in case congested situations.

However you do get the advantage of UDP checksum(with the UDP 8 byte header,
which has the UDP 16 bit checksum field), which is run for the payload
contents of the packet too, unlike IP which only has 16 bit header checksum
and no payload checksum, this would make it a second level of checksumming
besides OSPF packet checksum(also source/destination IP verification).
Reliability of flooding would still however need to be taken care of by OSPF
in case of running over UDP.

Do you see any advantage of running OSPF over UDP?

Thanks,
Vishwas

-----Original Message-----
From: Mareline Sheldon [mailto:marelinesYAHOO.COM]
Sent: Monday, February 18, 2002 2:15 PM
To: OSPFDISCUSS.MICROSOFT.COM
Subject: OSPF over UDP .. why NOT!

Hi,
RIP runs over UDP because of historical reasons.
BGP runs over TCP because the designers of BGP didn't
want the protocol to take care of issues like
fragmentation, re-assembly, reliable flooding, etc.

What advantages do we get in running OSPF over IP as
compared to running it over UDP. I was unable to find
many disadvantages except for the fact that by running
OSPF in UDP we bring an additional layer in between
the user and the protocol.

Another advantage which appears in running over IP is
that the intermediate routers need not support TCP/UDP
stack to forward OSPF packets.

I would like people experienced in this field to tell
me of the other advantages that we get in running OSPF
over IP.

with warm regards,
mareline s.

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