Solved: ospf application?

sarahr202 · ‎03-18-2010

HI everybody.

I hope you guys are doing great. I have this silly question.

Is ospf an application?

If ospf isve an application, then it should interact with application layer to send its packet. But my book says ospf use ip packet directly which led me to believe ospf can not be an application since it is not using above layers such as tcp or udp.

I will appreciate any correction .

thanks and have a good day.

Jon Marshall · ‎03-18-2010

sarahr202 wrote:

HI everybody.

I hope you guys are doing great. I have this silly question.

Is ospf an application?

If ospf isve an application, then it should interact with application layer to send its packet. But my book says ospf use ip packet directly which led me to believe ospf can not be an application since it is not using above layers such as tcp or udp.

I will appreciate any correction .

thanks and have a good day.

Hi Sarah

Long time since you were on these forums. Hope your'e well.

OSFP is a routing protocol and not an application in the same sense as telnet/SMTP/HTTP etc. It has it's own protocol number at the IP layer - protocol 89 from memory and you are right in that OSPF does not utilise the TCP/UDP transport layer or any layer above it.

Jon

View solution in original post

Giuseppe Larosa · ‎03-18-2010

Hello Sarah,

nice to hear from you.

this is the usual dualism between a protocol role (OSPF is a routing protocol that works at OSI L3) and its own encapsulation (how an OSPF packet looks like).

OSPF uses IP protocol type 89 so OSPF packets are at OSI layer 4 like TCP or UDP packets.

To be honest I wonder why there is so attention on this aspect.

The only side effect of this is that an OSPF packet is an OSPF packet with ip protocol type 89 and usually with ip precedence 6.

This is important when you need to create a traffic class in QoS in order to give some resources to the OSPF traffic.

Hope to help

Giuseppe

View solution in original post

Jon Marshall · ‎03-18-2010

sarahr202 wrote:

HI everybody.

I hope you guys are doing great. I have this silly question.

Is ospf an application?

If ospf isve an application, then it should interact with application layer to send its packet. But my book says ospf use ip packet directly which led me to believe ospf can not be an application since it is not using above layers such as tcp or udp.

I will appreciate any correction .

thanks and have a good day.

Hi Sarah

Long time since you were on these forums. Hope your'e well.

OSFP is a routing protocol and not an application in the same sense as telnet/SMTP/HTTP etc. It has it's own protocol number at the IP layer - protocol 89 from memory and you are right in that OSPF does not utilise the TCP/UDP transport layer or any layer above it.

Jon

sarahr202 · ‎03-18-2010

Thanks Jon. I am glad to see you guys. I am 2nd phase of training which army call advanced individual training. I wish i could have more time to come this forum and learn from you guys every day but the daily routine here only leaves me 30 min or even less.I will try to spend more time on the forum during weekend.

You have a good night Jon.

Giuseppe Larosa · ‎03-18-2010

Hello Sarah,

nice to hear from you.

this is the usual dualism between a protocol role (OSPF is a routing protocol that works at OSI L3) and its own encapsulation (how an OSPF packet looks like).

OSPF uses IP protocol type 89 so OSPF packets are at OSI layer 4 like TCP or UDP packets.

To be honest I wonder why there is so attention on this aspect.

The only side effect of this is that an OSPF packet is an OSPF packet with ip protocol type 89 and usually with ip precedence 6.

This is important when you need to create a traffic class in QoS in order to give some resources to the OSPF traffic.

Hope to help

Giuseppe

sarahr202 · ‎03-18-2010

Thanks Giuseppe. It is nice to see again after a long time.