[e2e] What should e2e protocols know about lower layers?

[Joe Touch]

Erik Nordmark wrote:

> Joe,
> 
> 
>>IPv4 certainly has a notion of local - the subnets to which you are 
>>directly connected. This is why, IMO, broadcasts are permitted there.
>>
> 
> If IPv4 has such a notion from a congestion control
> perspective then something is broken.


See RFC1112.


> RFC 2002 (Mobile IP) uses IPinIP tunneling to make what you thought was 
> local (in the same subnet prefix) be capable of being anywhere in the Internet.


Who said it had to be in the same subnet? IPinIP tunnels are 
point-to-point links, which means if they use subnets they are by 
definition misconfigured.

>  The only notion of "local" I've seen in IETF standards for IP
> is whether to ARP (or similar mechanisms for link-layers that don't
> use ARP) or send to a router. 


All broadcasts rely on the same notion of local - including BOOTP, RIP, 
RARP, etc.

Joe