ATM addressing

  • Article

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

ATM addressing

ATM addresses are needed to support the use of switched virtual connections (SVCs) through an ATM network.

At the simplest level, ATM addresses are 20 bytes long and have three distinct parts:

  • Network prefix

    The first 13 bytes identify the location of a specific switch in the network. The use of this portion of the address can vary considerably depending on its address format. Each of the three standard ATM addressing schemes provides information about ATM switch locations differently. These schemes include the data country/region code (DCC) format, the international code designator (ICD) format, and the E.164 format proposed by the ITU-T for international telephone numbering use in broadband ISDN networks.

  • Adapter media access control address

    The next 6 bytes identify a physical endpoint, such as a specific ATM adapter card, using a media access control layer address that is physically assigned to the ATM hardware by its manufacturer. The use and assignment of media access control addresses for ATM hardware are identical to how this addressing works for Ethernet, Token Ring, and other IEEE 802.x technologies.

  • Selector (SEL)

    The last byte is used to select a logical connection endpoint on the physical ATM adapter. Although all ATM addresses fit this basic three-part structure, there are significant differences in the exact format of the first 13 bytes, depending on the addressing format or whether the ATM network is for public or private use.

All of the three ATM address formats that are currently in widespread use (DCC, ICD, and E.164) include the following characteristics:

  • They comply with the Network Service Access Point (NSAP) addressing plan as proposed by the Open Standards Interconnection (OSI) protocol suite of the International Standards Organization (ISO).

  • Each can be used to establish and interconnect privately built ATM networks that support switched virtual connections (SVCs).