Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
2000-03-20
2004-08-31
Olms, Douglas (Department: 2661)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S389000, C370S401000, C370S351000
Reexamination Certificate
active
06785273
ABSTRACT:
FIELD OF THE INVENTION
The present application relates to the field of computer network traffic. It is more particularly directed to network traffic in which communication between applications occurs using a connectionless protocol.
BACKGROUND OF THE INVENTION
Traffic Engineering refers to the capability of sending packets along different paths on a network in order to obtain particular performance goals such as uniform traffic load distribution in the network. A uniform load distribution is useful for networks which are required to meet a desired level of service and/or are required to conform to specific service level agreements.
The Internet Protocol (IP) constitutes the bulk of network communication in the current age, and it would be beneficial if packets belonging to the IP protocol could be redirected as desired along different paths of the network. However, the basic IP protocol is not designed to permit traffic engineering in this manner. IP is a connectionless protocol which uses the destination address for forwarding packets. IP packets are routed solely based on their destination addresses. As a result, all packets that are destined to go a specific set of destination addresses are constrained to follow a fixed path in the network.
If there is enough capacity in the network, then the path taken by all the packets does not constitute a problem. However, there are many cases where the traffic on a specific path exceeds the capacity available on the path. As a result, it is quite common to experience network congestion and packet loss in an IP network. In many of these cases, an alternate path with extra capacity is available on the network. However, it is not possible to send packets on that path using the normal IP protocols.
In order to achieve traffic engineering, many traffic operators depend on other protocols such as Frame Relay (FR) or ATM to establish connections which can be routed in the network according to the capacity available in the network. ATM and FR are examples of connection-oriented protocols. The IP packets are then multiplexed onto the different ATM or Frame Relay connections. Another connection-oriented approach is the multi-protocol label-swapping (MPLS) approach. MPLS also depends on establishing connections at a layer below the IP layer.
While schemes such as building IP over ATM, Frame Relay or MPLS can be used as effective schemes for traffic engineering, they require the development and operation of a different network which effectively supersedes the IP network. These approaches are unable to work over IP networks which are built upon faster but different underlying link technologies. Another example is the fast Ethernet or the Gigabit Ethernet, which can form part of a network backbone, but does not use the connection oriented paradigm of ATM, FR or MPLS. Another problem associated with these approaches is that they require an extra layer of encapsulation of IP packets. The additional layering adds headers which can result in potential packet fragmentation, and reduced bandwidth.
SUMMARY OF THE INVENTION
Accordingly, an aspect of the present invention presents methods and apparatus by which traffic engineering is supported in a connectionless protocol network constituted by a core of plain routers, without dependencies on the underlying link protocol. The IP is used as an example of a connectionless protocol.
Another aspect of the present invention presents an apparatus for an access router with which a network operator can support traffic engineering on a core network of plain routers supporting a connectionless protocol.
REFERENCES:
patent: 6266335 (2001-07-01), Bhaskaran
patent: 6560236 (2003-05-01), Varghese et al.
patent: 6598071 (2003-07-01), Hayashi et al.
Aker David
Herzberg Louis P.
International Business Machines - Corporation
Olms Douglas
Wilson Robert W.
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