Why is UDP needed?

I got to thinking of this when I was doing some packet captures. Why is UDP header used with a unique port number instead of just assigning each application a unique ID in the IP header?

Wouldn't this still allow application multiplexing and allow less packet overhead?

Find more posts tagged with

Free for TechExams community: Cybersecurity salary guide

Compare cert salaries and plan your next career move

Button

Comments

UnixGuy

I thought each UDP (or TCP) packet has the port number of the application it's destined to ?

tiersten

The IP protocol field is only 8 bits. Most of them have been preassigned in RFC790.
You'll end up with nasty hacks and special cases because you're overloading the field and not using it for its intended purpose. The layers are split for a reason. IP is for routing.

tiersten

UnixGuy wrote: »

I thought each UDP (or TCP) packet has the port number of the application it's destined to ?

It does. gojericho0 wants to know why you don't just use the protocol field in the IP header as a port number.

gojericho0

tiersten wrote: »

The IP protocol field is only 8 bits. Most of them have been preassigned in RFC790.
You'll end up with nasty hacks and special cases because you're overloading the field and not using it for its intended purpose. The layers are split for a reason. IP is for routing.

Thanks! this cleared things up greatly.