Difference of Protocols between running directly over IP and UDP

[karenmelkonyanstu]

Hello,

There are protocols which run directly over IP for example  VRRP or OSPF.
However there are protocols which do the same thing but are running over UDP(HSRP) or TCP(BGP)
For example HSRP and VRRP are both First Hop Redundancy protocols but for some reasons one is using UDP and another runs directly over IP.
So my question is - What is advantage or disadvantage running protocol directly over IP VS over UDP?

[MHM Cisco World]

First the IP is layer 3

And tcp/udp is layer 4

And protocols run over layer 4 is also run over layer 3.

Hsrp also use udp 

And as a rule any protocol use multicast is use udp.

And any protocol use unicast between two peer and need high reliability use tcp like bgp. 

MHM

[karenmelkonyanstu]

Thanks for prompt response.
May be I will re-phrase it.
RIP is Routing Protocol
EIGRP is also Routing Protocol
OSPF is Routing protocol
But for some reasons RIP is using UDP , OSPF runs over IP , EIGRP also runs  over IP , BGP is using TCP.
So my question is weather there are any advantages or disadvantages between all three options?
For example Why they didn't run OSPF over UDP or TCP? Why they didn't run RIP over TCP? Why VRRP  is not running over UDP?
Is it just a matter of preferences of Developers who invent protocols or there are some valid reasons behind the scenes ?

[Joseph W. Doherty · Accepted solution]

"Is it just a matter of preferences of Developers who invent protocols or there are some valid reasons behind the scenes ?"

Usually, it's a choice between not reinventing the wheel vs. the "flexibility" of not being restricted by the limitations of someone else's wheel.

Similar logic for any software.  For example why tftp uses UDP while FTP uses TCP?