[ih] Why was DVMRP put into IGMP?

[Steve Deering]

John,

I don't remember why, but if I had to guess, it was probably because I had obtained the assignment of the the IP Protocol number for IGMP from Jon Postel, but didn't think I could justify, to Jon's satisfaction, getting another Protocol number or well-known UDP port number for what was just a grad-student's experimental protocol.  Similarly, extending the RIP specification probably seemed above my pay grade.  So, likely no architectural reason, just a convenience at the time.

Steve


On Sep 1, 2015, at 2:03 PM, John Kristoff <jtk at depaul.edu> wrote:

> I'm curious why DVMRP was put into IGMP, as opposed to being put on top
> of UDP or perhaps even as an extension to RIP, which DVMRP's close
> cousin used.
> 
> Maybe the use of IGMP by DVMRP was just to keep IP multicast protocols
> essentially together, or was there some other rationale?
> 
> No other IP multicast routing protocol that I'm aware went this route
> and only a small handful of little used measurement features ended up
> going into IGMP, performing something beyond its core functionality of
> group membership maintenance.
> 
> Perhaps Steve Deering or something who was involved in this early work
> can shed some light on the original ideas?  Thank you,
> 
> John
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