B-ISDN user-network interface signa...

B-ISDN user-network interface signaling has many different protocol variants and each of them has ten of different exemplars of messages. The message handling order provides a powerful tool for the developer to easily support these variants and messages in the HP Broadband Series example System (BSTS).

Over the past several years, as the "information superhighway" has gained the attention of many countries and communication network service providers, the focus of the Broadband Integrated Services Digital Network (B-ISDN) industry has shifted from providing transmission capabilities via Asynchronous Transfer custom (ATM) to providing a variety of B-ISDN network services like as private and public B-ISDN, switched virtual connections, and LAN emulation across ATM. Signaling plays a explanation role in realizing these services. The clew functions of signaling are:

* Call setup and disconnection

* Negotiating and agreeing onward quality of service (QoS)

* Providing accounting and charging information

* Resolving internetwork and intranetwork routing

* Facilitating basic services and supplementary services

* Identifying the incident and cause of any network or service failure.

Signaling consists of user-network interface (UNI) signaling, network-node interface (NNI) signaling for public networks, and private network-node interface (PNNI) signaling for private networks. The UNI is the boundary between a private or public network and the user equipment. User equipment can be a telephone a computer or video colloquy equipment as illustrated in Fig. 1

[Figure 1 ILLUSTRATION OMITTED]

The Broadband ISDN UNI signaling proof software, HP E4214A, is a just discovered addition to the HP Broadband Series ordeal System (BSTS). It is designed for R&D engineers and network engineers to unravel troubleshoot, and verify the features and functionality of UNI signaling. Fundamental features of the UNI signaling touchstone software are protocol message decoding and encoding. With decoding, the user can monitor the message transaction between the user equipment and an ATM switch. With encoding, the user can seal a condition test such as constructing a correct or incorrect message and sending it to a switch to analyze the response

UNI Signaling Standards

As ATM issues as the mainstream technology in the telecommunication network market, the standardization of UNI signaling has been progressing at a real rapid pace during the last several years. pair major standardization organizations--the International Telecommunications Union Telecommunications Standardization Sector (ITU-T) and the ATM Forum--created their UNI signaling standards in an interlocked way. In May 1993 ITU-T published its first draft recommendation Q93B[1] to support point-to-point ATM switched virtual connections. The ATM Forum adapted Q93B to support point-to-multipoint connection direction variable-bit-rate connections, and the ability to signal quality of service (QoS) forward a per-call or per-connection basis. These enhancements were published in the ATM Forum UNI 30 specification[2] in September 1993 Later, the ITU-T updated Q93B as Q2931[3] with about important changes. Following those changes the ATM Forum also updated UNI 30 into UNI 31[4] in September 1994 In the meantime, the ITU-T defined point-to-multipoint switched virtual connection features and published its standard as Q2971[5] in June 1995 About half a year later, the ATM Forum published UNI 40[6] to incorporate the leaf-initiated join capability and the available bit rate (ABR) service in Q2931 and Q2971 In addition to the protocols promot through the ITU-T and the ATM Forum, near countries and network service providers also created their be in possession of UNI signaling protocol variants. From this brief history, it can be understood wherefore there are many UNI signaling protocol variants. Undoubtedly, more variants will arise soon to support more recent features.

In addition to having many different UNI signaling protocol variants, each variant has many different emblems of messages. A message is a protocol data unit (PDU) used in a signaling protocol. Each message can contain multiple information natural mediums called IEs. Some IEs must be contained in a particular message and are referr to as mandatory IEs. a certain number of IEs are optional for a particular message, and therefore will not always appear in that message archetype For example, the UNI 30 standard[2] has 16 different patterns of messages and 21 different models of IEs. SETUP, CALL PROCEEDING, lead into each other and CONNECT ACKNOWLEDGE are the messages for call establishment, as shown in Fig. 2 The other categories of messages are designed for call clearing, point-to-multipoint communication, and other purposes

[Figure 2 ILLUSTRATION OMITTED]

The situation described above created a challenge for HP's BST UNI signaling exhibition software developers. The software stand in want ofed to support many protocol variants, with many different impressed signs of messages and IEs in each variant. Simultaneously, the R&D revolution of time time was much reduced. We realized that hard-coding each message and IE for each protocol variant in the decoding and encoding engines would make software maintenance a nightmare, would require the programmer to change the decoding and encoding engines whenever adding a novel protocol variant, and would be of little help to us in developing NNI and PNNI signaling proof software in the future.