The IP over ATM Mailing List Archive by date

[Maryann Perez Maher <perez@isi.edu>]

] 	2) With NULL encapsulation, one needs some mechanism to distinguish
] 	ARP frames from IP frames, and we can't do this when connections are
] 	established because the draft signaling standard doesn't provide a
] 	mechanism.  Using LLC/SNAP encapsulation allowed this

The signaling RFC (1755) describes how to signal for both LLC/SNAP 
encapsulation and NULL encapsulation. It also describes how to
negotiate encapsulations so that VCs for IP can be established
among IP peers that 'talk' NULL encapsulation. NULL encapsulation makes
possible the use of _separate_ VCs for IP and ARP traffic, therefore
allowing endsystems to distinguish IP packets from ARP packets.

Maryann