ATM network addressing is similar to Novell Netware network addressing in that and endsystem has an address with two distinct pieces - a network piece and a local piece. It turns out this is a nice feature especially when analyzing and troubleshooting a network. Since ATM addresses are made up of a network part and a local part, a misbehaving client can be tracked down easily based on its ATM address. Contrast this to a mis-behaving IP network host. The IP addressing scheme is totally distinct from the local (LAN) addressing scheme -so knowing an IP address is not enough to isolate a misbehaving client in this case (you need to know the local address of the client).
This shows that an ATM address can be represented in a naming format much like an IP address. Note that ATM device names will use the same domain name services (DNS) that IP hosts use - with an extension that maps 20-byte local addresses to a name.
As is the case for IP addresses - there is a process in place for network managers to acquire unique network name and address space. In the case of ATM there are several registration authorities from which one can acquire ATM code points (in the US) - namely, the National Institute of Standards and Technology (NIST) and the American National Standards Institute (ANSI). Basically, ANSI or NIST assigns a 3-octet organization identifier (ORG) code point. This ORG field follows 4 octets of identification bits which identify the country and registration authority (e.g., ANSI). Thus, once an organization obtains and ORG value, the 7 most significant octets of the ATM address uniquely identify the ATM network of that organization. The owning organization is then responsible for the encoding of the remaining 6 octets in the ATM network part of the ATM address. Recall that the least significant 7 octets of the ATM address are locally (client) significant and associated with the ATM client device.
