Re: compare layer of RIP vs. OSPF


Choonho wrote:
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.

Hmmm ...
That is an interesting question to which I wish I could offer a good
answer with many adventurous tales. Alas, no such luck.

He's my best speculation.

Long before RIP was formalized, routed was being used as a routing
protocol. In effect, routed defined the RIPv1 protocol by default.

UDP was used to avoid the overhead of TCP and a separate IP protocol
type was not an option. You don't just go out and make your own IP
protocol types. Applications, like routed, are not limited in that
fashion and only need a "well known" port to run on.

OSPF was designed _before_ it was implemented and put in use widely.
The designers used the option to request and get an IP protocol type
assigned to them. Why this instead of UDP?

Overhead efficiency and flexibility are my candidates for an answer.
Why waste time passing through UDP?

sorry, that's the best I can do ...
prg

"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


.

Relevant Pages

  • Re: compare layer of RIP vs. OSPF
    ... I also know that OSPF has a protocol number in the IP header, but RIP does ... Every one knows that RIP and OSPF protocols are routing protocols. ...
    (comp.os.linux.networking)
  • Re: Redundant links between subnets
    ... protocol doesnt get events like interface state changes instantly using ... protocol to react quickly to outages. ... thought OSPF will help. ... does, and hello packets are frequent enough, my problem is solved. ...
    (comp.dcom.sys.cisco)
  • Re: I want my MOM
    ... >> 5) Require that the header MUST have the content-length ... >> again slam the server with never ending data until it dies. ... server to have a reason to boot bad clients. ... Another thing a pre-sized protocol does is make it much harder to have ...
    (comp.lang.ruby)
  • Re: Redundant links between subnets
    ... layer 2 links redundant. ... Then I've been digging around OSPF and EIGRP, ... default timers for OSPF are for 10 sec "tick" - so dead timer would give you ... protocol to react quickly to outages. ...
    (comp.dcom.sys.cisco)
  • Sygate Firewall warning
    ... Ethernet II (Packet Length: 76) ... Internet Protocol ... Header checksum: 0x76cd ... Source port: 1161 ...
    (alt.computer.security)