Sun Microsystems 3U manual ATM Addresses and Address Registration, 1ATM Address Fields

The transparency to IP is enabled in different ways in Classical IP and LAN Emulation. Those differences will be discussed in later sections of this chapter.

SunATM signalling conforms to the user network interface (UNI) specification of the ATM Forum. Versions 3.0, 3.1, and 4.0 of that specification are supported. This signalling, called Q.2931, runs on top of QSAAL and uses VC 5 for signalling as specified in the Forum specification.

ATM Addresses and Address

Registration

UNI signalling uses ATM addresses for signalling. Every ATM interface has an ATM address in addition to its IP address.

ATM addresses, like Network Service Access Point (NSAP) addresses, are 20 octets long. The End System Identifier (ESI) field within the ATM address is a unique six-octet value; this can be the IEEE hardware MAC address conventionally associated with every network interface. The Selector field is one octet long. The 13 octets that make up the rest of the ATM address are called the Network Prefix, and are derived from the ATM switch fabric to which the interface is connected. Every ATM switch fabric is configured with a 13-octet prefix.

On a SunATM host, the prefix associated with the local switch fabric is represented by the $prefix variable. Its value is obtained by the system at configuration time.

1 octet

Determined by the ATM switch/13

ESI/6 octets

SEL

FIGURE 7-1ATM Address Fields

The UNI specification specifies the Interim Local Management Interface (ILMI) service interface for a client to learn and register its ATM address. The ILMI service interface is based on the use of SNMP over AAL5. In the SunATM software package, ILMI service is provided by an address registration daemon, ilmid.

66 SunATM 3U CompactPCI Adapter Installation and User’s Guide • February 2001