NSAP address
Encyclopedia
A Network Service Access Point address (NSAP address), defined in ISO/IEC 8348, is an identifying label for a Service Access Point
(SAP) used in OSI
networking.
These are roughly comparable to IP address
es used in the Internet Protocol
; they can specify a piece of equipment connected to an Asynchronous Transfer Mode
(ATM) network. A specific stream, analogous to a TCP/IP port
or socket
, is specified by using a Transport Service Access Point (TSAP). ATM can also use a Presentation (PSAP) and Session (SSAP) Access Point, but these may also be unspecified; this is up to the application.
NSAP addresses are allocated by the International Organization for Standardization
(ISO), through a system of delegated authorities, which are generally national standards organizations. One of the schemes to generate NSAPs uses E.164
which is the addressing format describing telephone numbers.
NSAP addresses do not specify where a network terminal is located. Routing
equipment must translate NSAP addresses to SNPAs (SubNetwork Point of Attachment) to route OSI packets; VCI
(Virtual Circuit Identifier) numbers are an example of a datalink layer SNPAs in ATM; when OSI packets are sent encapsulated in IP packets the IP address is considered an SNPA.
Currently SDH/SONET networks are a major part of the network infrastructure and NSAPs are used extensively. They are usually assigned by the Network Management/NOC personnel and agreed upon within an organization to be unique (to that organization and based on geographical location using country code telephone prefixes) and are required before any operational connectivity is established at the commissioning stage.
NSAP addresses are used in the following OSI-based network technologies:
NSAP-style addresses are used in the IS-IS
routing protocol.
Service Access Point
A Service Access Point is an identifying label for network endpoints used in Open Systems Interconnection networking.When using the OSI Network Layer , the base for constructing an address for a network element is an NSAP address, similar in concept to an IP address...
(SAP) used in OSI
OSI model
The Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...
networking.
These are roughly comparable to IP address
IP address
An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...
es used in the Internet Protocol
Internet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
; they can specify a piece of equipment connected to an Asynchronous Transfer Mode
Asynchronous Transfer Mode
Asynchronous Transfer Mode is a standard switching technique designed to unify telecommunication and computer networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells. This differs from approaches such as the Internet Protocol or Ethernet that...
(ATM) network. A specific stream, analogous to a TCP/IP port
Computer port (software)
In computer programming, port has a wide range of meanings.A software port is a virtual/logical data connection that can be used by programs to exchange data directly, instead of going through a file or other temporary storage location...
or socket
Berkeley sockets
The Berkeley sockets application programming interface comprises a library for developing applications in the C programming language that perform inter-process communication, most commonly for communications across a computer network....
, is specified by using a Transport Service Access Point (TSAP). ATM can also use a Presentation (PSAP) and Session (SSAP) Access Point, but these may also be unspecified; this is up to the application.
NSAP addresses are allocated by the International Organization for Standardization
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
(ISO), through a system of delegated authorities, which are generally national standards organizations. One of the schemes to generate NSAPs uses E.164
E.164
E.164 is an ITU-T recommendation that defines the international public telecommunication numbering plan used in the PSTN and some other data networks. It also defines the format of telephone numbers. E.164 numbers can have a maximum of fifteen digits and are usually written with a + prefix...
which is the addressing format describing telephone numbers.
NSAP addresses do not specify where a network terminal is located. Routing
Routing
Routing is the process of selecting paths in a network along which to send network traffic. Routing is performed for many kinds of networks, including the telephone network , electronic data networks , and transportation networks...
equipment must translate NSAP addresses to SNPAs (SubNetwork Point of Attachment) to route OSI packets; VCI
Virtual Circuit Identifier
A Virtual Channel Identifier is a unique identifier which indicates a particular virtual circuit on a network. It is a 16-bit field in the header of an ATM cell...
(Virtual Circuit Identifier) numbers are an example of a datalink layer SNPAs in ATM; when OSI packets are sent encapsulated in IP packets the IP address is considered an SNPA.
Currently SDH/SONET networks are a major part of the network infrastructure and NSAPs are used extensively. They are usually assigned by the Network Management/NOC personnel and agreed upon within an organization to be unique (to that organization and based on geographical location using country code telephone prefixes) and are required before any operational connectivity is established at the commissioning stage.
NSAP addresses are used in the following OSI-based network technologies:
- ATMAsynchronous Transfer ModeAsynchronous Transfer Mode is a standard switching technique designed to unify telecommunication and computer networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells. This differs from approaches such as the Internet Protocol or Ethernet that...
switched virtual circuit networks - X.25X.25X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
(see ITU-TITU-TThe ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
X.121X.121X.121 is the ITU-T address format of the X.25 protocol suite used as part of call setup to establish a switched virtual circuit between Public Data Networks , connecting two network user addresses...
for addressing in public data networks) - Frame relayFrame relayFrame Relay is a standardized wide area network technology that specifies the physical and logical link layers of digital telecommunications channels using a packet switching methodology...
- IS-ISIS-ISIntermediate System To Intermediate System , is a routing protocol designed to move information efficiently within a computer network, a group of physically connected computers or similar devices....
- SDHSynchronous optical networkingSynchronous Optical Networking and Synchronous Digital Hierarchy are standardized multiplexing protocols that transfer multiple digital bit streams over optical fiber using lasers or highly coherent light from light-emitting diodes . At low transmission rates data can also be transferred via an...
& SONETSonetSonet may refer to:* Sonet Records, European record label* Synchronous optical networking * Saab Sonett...
networks.
NSAP-style addresses are used in the IS-IS
IS-IS
Intermediate System To Intermediate System , is a routing protocol designed to move information efficiently within a computer network, a group of physically connected computers or similar devices....
routing protocol.