Re: compare layer of RIP vs. OSPF

Thank you for your apply.

I also know that OSPF has a protocol number in the IP header, but RIP does
not.
I want to know a historical reason why RIP does not have a protocol number
in the IP header.

"prg" <rdgentry1@xxxxxxxxxxxxx> wrote in message
news:1140791365.064710.227390@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Choonho wrote:
Hello

Every one knows that RIP and OSPF protocols are routing protocols.
My question is the difference between them.

RIP uses UDP port 520.
This means that RIP format in the network layer has following shape.

+---------------+----------------+-----------------------+
| IP header | UDP header | RIP header
|
+---------------+----------------+-----------------------+

However
OSPF is directly attached next to the IP header like

+---------------+-----------------+
| IP header | OSPF header |
+---------------+-----------------+

Both protocols have similar functions like routing.
Why does RIP use UDP header, OSPF does not use UDP header?

The IP header carries all the needed info, ie., OSPF does not need the
port numbers added by a UDP header.

Specifically, the IP PROTOCOL field for OSPF is 89. RIP has no
specific protocol field reserved for its use; it uses UDP (PROTOCOL
field is 17).

See:
http://www.networksorcery.com/enp/protocol/ip.htm#Protocol

hth,
prg



.

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