Programmable transport and network architecture

Details Programmable transport and network architecture Programmable transport and network architecture

1998-07-16

2003-04-01

Hsu, Alpus H. (Department: 2665)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S258000

Reexamination Certificate

active

06542511

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to efficient transfer of digital information among nodes. In particular, it is directed to a novel digital network in which digital information is exchanged among nodes in containers of any number of data units.
BACKGROUND OF INVENTION
To date, communication networks have been primarily used for voice services and support limited data and computer services. In recognition of the predominance of voice traffic, a circuit switched channelized architecture evolved and was optimized for telephony. Data and computer communications access and transport have been provided as an overlay on this channelized infrastructure.
Although many data technologies have been developed, the advent and subsequent popularity of the Internet, coupled with its ability to support multiple services, including telephony, is changing the way users communicate and do business. Today, telecommunications networks are shifting from specialized networks toward multipurpose multi-functional networks.
The emerging data network must be able to grow to a much-higher capacity than the capacity of today's voice and data networks. In addition to the huge-capacity requirement, the emerging networks must provide diverse and versatile services. The multiplicity of connection protocols, and the effort required for their interworking, inhibit the ability of the network to provide service diversity. The simplest network would be fully connected, allowing every networking device to have a physical connection to every other networking device. However, as the network size grows, this fully-meshed structure rapidly becomes impractical. Due to the spatial variation of traffic loads, and the typically large modular sizes of transport links, a fully-meshed network normally leads to underutilized transport facilities.
Currently, transport-capacity sharing is based on coarse-granularity, where point-to-point connections are defined as multiples of standard tributaries, such as OC
3
, OC
12
, etc. This renders tandem switching—at a lower granularity—necessary to establish end-to-end connections with an acceptable quality-of-service (QOS) and an acceptable overall network efficiency. A low-connectivity network with excessive tandem switching may however lead to an uneconomical network, due to the increased number of hops between origin and destination and the cost of processing in intermediate nodes. Tandem switching in the multi-protocol environment is rather complicated, and several techniques have been proposed to reduce the processing at intermediate nodes by creating “short-cuts”, see for example, an article in IEEE INFOCOM, 1996, pp. 1251-1260, “Flow—Labelled IP: A Connectionless Approach to ATM” by P. Newman et al. In addition, tandem switching adds variable delay and increases latency.
The multiplicity of communications protocols and the need for coexistence between new networks and legacy networks complicate the network planning function. In addition, QOS is difficult to realize in such a heterogeneous network. Currently, IP-based networks do not take the QOS into account, and one of the approaches to provide QOS assurance is to interwork—at a prohibitive cost—with an underlying switch-based network, such as ATM networks. The complexity and fragility of such approaches are formidable impediments to network scaleability.
Traditional transport systems can offer a meshed network by providing direct interconnections between the networking devices. However, the connections would be based on channelized time division multiplexing, where the bandwidth allocated to a node-pair is fixed and dedicated to the node-pair. When the connection between two devices is inactive for some period of time, the transport bandwidth is still reserved so that it cannot be utilized by other active connections. Thus the networking device interfaces may not be as efficiently utilized as in the tandem approach which allows interconnections from many networking devices to share the interface to a given device.
U.S. Pat. No. 5,293,376, issued Mar. 8, 1994 (White), describes an upgradable telecommunication network which comprises a plurality of interconnected nodes or central offices, such as a SONET ring network. In its network, a unique controller enables a subscriber to change the central office or node in the network to which it is connected without changing the telephone number of the subscriber location.
U.S. Pat. No. 5,247,518, issued Sep. 21, 1993 (Takiyasu et al), teaches a high speed ring LAN system in which SONET subframes flow in a time-divisional n-multiplexed format. The respective node devices inserted in the transmission path have one or more ports to accommodate sub-LANs or public networks. Information is exchanged in units of a fixed-length container (packet) between a received SONET subframe and an asynchronous port, whereas information is exchanged in units of a byte between the SONET subframe and a synchronous port.
U.S. Pat. No. 5,406,401, issued Apr. 11, 1995 (Kremer) describes a technique of selective tributary switching in a bi-directional ring transmission system. The patent describes how selective switching in a bi-directional transmission system is used to realize selective tributary switching. A portion of bandwidth of a link that has been provisioned to be line-switched is governed by the set-up and take down procedures of full line-switching. The remaining bandwidth can be left unprotected but can be path-switched, because the line-switching functionality is combined with path-switching functionality in the same ring transmission system.
A fully-meshed network, as depicted in
FIG. 1
, is not scaleable to cover a large number of nodes, unless the link capacities are elastic and can be modified rapidly to follow the traffic-demand variation. With fixed capacities and fluctuating traffic demand, the transport utilization drops rapidly as the number of nodes increases. An elastic network, however, would allow all the connections to share a common pool of capacity through paths whose capacities are dynamically adjustable.
The envisaged network to be described herein has a high-connectivity structure. The basic requirements of such a network are simplicity, scale—ability, transport efficiency, the ability to accommodate existing legacy subnetworks, and—most importantly—high reliability. There are several candidate topologies which, primarily, fall into two main categories: cross-connection and ring sharing.
Both cross-connection-based and ring-based networks can be configured to be fully meshed or almost fully meshed. A cross-connection-based network would normally have a lower connectivity than a ring-based network and is not discussed in this disclosure. A ring structure lends itself to fine capacity partitioning with relatively simple controls. Ring sharing can be achieved in several ways; for example by using ATM nodes and SONET rings, as depicted in FIG.
2
. However, a flexible-transport layer as shown in
FIG. 3
would achieve a more economical solution. A path of controlled variable capacity for each node pair is established in the network, thus creating a flexible fully-connected network. Each path may carry multiple traffic classes, and the capacity of the path can be dynamically shared among the classes at the container-packing stage. The network can accommodate a mixture of data, voice, and video traffic of both unicast and multicast nature. The multiclass service discipline is decided only at the originating and terminating nodes.
A pending U.S. patent application Ser. No. 08/755,431 filed on Nov. 21, 1996 for “Transport Architecture and Network Elements” has inventors common to those of the present application and describes a ring structure with capacity partitioning. The invention described therein allows many networking devices to be interconnected with efficiently utilized interfaces, without incurring the cost and service degradation of a tandem device. A domain is defined where every networking device within the domain is connected to every other networ

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