Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
2002-09-30
2004-06-01
Pham, Chi (Department: 2667)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S367000
Reexamination Certificate
active
06744768
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates in general to the field of communications, and in particular, by way of example but not limitation, to using broadband transport for narrowband telephony and data communications.
2. Description of Related Art
The increasing interest for high band services such as multimedia applications, video on demand, video telephone, and teleconferencing has motivated development of the Broadband Integrated Service Digital Network (B-ISDN). B-ISDN is based on a technology known as Asynchronous Transfer Mode (ATM) and offers considerable extension of telecommunications capabilities.
ATM is a packet-oriented transfer mode which uses asynchronous time division multiplexing techniques. The packets are called cells and traditionally have a fixed size. A standard ATM cell comprises 53 octets, five of which form a header and 48 of which constitute a “payload” or information portion of the cell. The header of the ATM cell includes two quantities that are used to identify a connection in an ATM network over which the cell is to travel. These two quantities include the Virtual Path Identifier (VPI) and the Virtual Channel Identifier (VCI). In general, a virtual path is a principal path defined between two switching nodes of the network; a virtual channel is one specific connection on the respective principal path.
At its termination points, an ATM network is connected to terminal equipment, e.g., ATM network users. In between ATM network termination points, there are typically multiple switching nodes. The switching nodes have ports which are connected together by physical transmission paths or links. Thus, in traveling from an originating terminal equipment to a destination terminal equipment, ATM cells forming a message may travel through several switching nodes and the ports thereof
Of the multiple ports of a given switching node, each may be connected via a link circuit and a link to another node. The link circuit performs packaging of the cells according to the particular protocol in use on the link. A cell that is incoming to a switching node may enter the switching node at a first port and exit from a second port via a link circuit onto a link connected to another node. Each link can carry cells for multiple connections, with each connection being, e.g., a transmission between a calling subscriber or party and a called subscriber or party.
The switching nodes each typically have several functional parts, a primary of which is a switch core. The switch core essentially functions like a cross-connect between ports of the switch. Paths internal to the switch core are selectively controlled so that particular ports of the switch are connected together to allow a message to travel from an ingress side/port of the switch to an egress side/port of the switch. The message can therefore ultimately travel from the originating terminal equipment to the destination terminal equipment.
While ATM, because of the high speed and bandwidth that it offers, is envisioned as the transport mechanism for more advanced services such as B-ISDN, it nevertheless must be recognized that the current narrowband networks (e.g., Public Switched Telephone Networks (PSTN), ISDN, etc.) will remain in use (at least in part) for quite some time. It has taken decades for the present voice switched telephony networks (e.g., PSTN, ISDN, etc.) to reach their present advanced functionalities. While ATM networks are being built, the ATM networks will likely not easily acquire all the functionalities of advanced voice communication. Therefore, at least initially, ATM networks
odes will in some instances be added to parts or will replace parts of circuit switched telephony networks. In such instances, ATM will be used for transport and switching. ATM can actually be used as a single transport and switching mechanism for multiple other networks, including multiple other different types of networks. For example, a single ATM network can be used to transport and switch communications from mobile networks (e.g., Public Land Mobile Networks (PLMNs)), Internet protocol (IP)-based networks (e.g., the Internet), etc., as well as landline networks such as PSTNs and ISDNs.
U.S. Pat. Nos. 5,568,475 and 5,483,527 to Doshi et al., for example, incorporate ATM switches for routing telephony voice signals between Synchronous Transfer Mode (STM) nodes. The ATM switches use a signaling system No. 7 (SS#7) network to establish a virtual connection, rather than a circuit switched connection, as would be the case in a pure STM network. The signaling system No. 7 (SS#7) network of U.S. Pat. Nos. 5,568,475 and 5,483,527 includes signal transfer points (STPs) that are connected by special physical links to each of the ATM switch nodes. For call setup, for example, signaling messages are relayed through the signaling system No. 7 (SS#7) network In such relaying, a non-ATM STP receives the signaling message and advises its associated ATM node of the call setup. The associated ATM node may then identify idle resources to be used for forwarding voice signals to the next ATM node once the call has been setup, and it may prepare its own signaling message to be used in the relay.
The signaling message for the relay that is prepared by the ATM node is returned to its associated STP, which forwards the signaling message via the signaling system No. 7 (SS#7) network to another STP associated with the next ATM node. Such relaying continues until the signaling message reaches an STP of an STM local exchange carrier (LEC). Once the call has been set up, the ensuing speech (or voice-band data) is transported via the ATM nodes. STM/ATM terminal adapters are situated between the STM network and the ATM network for packing samples of voice signals as received from the STM network into ATM cells for application to the ATM network, and for unpacking ATM cell payloads to obtain voice signals for application to the STM network from the ATM network. The incorporation of ATM into an STM network in the particular manner as described above thus involves a non-ATM signaling network alongside the ATM nodes. Furthermore, each STP node associated with an ATM node performs only call control functions in the network of Doshi et al. Otherwise and in general, call control and connection control is traditionally combined in conventional communication nodes.
With reference now to
FIG. 1A
, a conventional unified communications node is illustrated at
100
. The conventional unified communications node
100
may represent any general purpose switching node in a telecommunications network such as a PSTN. Within the conventional communications node
100
, the call control
105
functions and the connection control
110
functions are united. The call control
105
and the connection control
110
functions together encompass the entire seven (7) layers of the Open System Interconnection (OSI) protocol. These seven (7) layers are denoted as the physical, data link, network, transport, session, presentation, and application layers. Accordingly, the conventional communications node
100
may perform all functions related to both switching intelligence and switching fabric. Conventional communication nodes
100
are not, however, capable of handling the interworking between (i) narrowband telephony and data communications and (ii) broadband communications using faster and higher bandwidth networks, such as ATM networks.
With reference now to
FIG. 1B
, a conventional approach to separating functions of the conventional unified communications node of
FIG. 1A
is illustrated generally at
150
. Conventional approaches attempt to meet the stringent demands of interworking narrowband telephony and data communications with broadband networks using ATM by separating control functions. Specifically, call control
155
functions are separated from connection control
160
functions. The call control
155
functions are thereby made independent of any particular set of connection control
160
fun
Nylander Tomas
Vikberg Jari Tapio
Pham Chi
Telefonaktiebolaget LM Ericsson
Waxman Andrew M
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