Label switching system

Abstract

A packet router in a label switching system includes a logical router configuring module for logically dividing a label switching router (LSR) into a plurality of LSRs each having a label switching function, and a module for specifying, when setting a label switched path on the basis of an explicit route specified, a port or a port group of an egress node. With this construction, a label switching architecture in an ATM network for actualizing MPLS (label switching) can be mapped to an ATM-Switch base system architecture, and a granularity of function (Constraint Base Routing) of specifying a variety of routes provided by MPLS can be attained.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates generally to a label switching system, and more particularly to an explicit routing method and a packet router in this label switching system.[0002]The label switching is a key technology for actualizing an Intranet / Internet backbone oriented high-speed transfer, traffic load sharing and band control on a full scale. The label switching also functions to match a routing process at an IP level (Layer 3) with a switching process on a lower layer (Layer 2) where ATM, a frame relay, Ethernet etc are conducted, and perform packet forwarding (transmission, exchange and transfer) on Layer 2 according to [labels] attached to IP packets.[0003]Standardization of this label switching are now being promoted as MPLS (Multi Protocol Label Switching) by MPLS-WG of IETF (Internet Engineering Task Force). Further, ITU (International Telecommunication Union) also examines the use of MPLS in IP over ATM (IP / ATM) in the public network.[0004...

AI Technical Summary

Benefits of technology

[0067]According to the present invention, it is feasible to actualize MPLS on the packet router taking the architecture of mounting an IP / MPLS forwarder in an adapter at an egress for packets in terms of a mounting space and a mounting cost. As a result, MPLS utilizing the existing system architecture can be easily mounted.

[0068]Further, according to the present invention, when setting an explicit LSP, it is possible to attain routing elaborate enough to specify the ports or the port groups of the relay node and of the egress node. As a result, there is yielded a effect of expanding a range of utilizing an application making use of MPLS such as traffic engineering etc.

Problems solved by technology

According to this method, however, the CPU analyzes the packets, searches a routing table and edits a packet header, and therefore high-speed forwarding can not be actualized.

According to this method, when actualized based on the ATM switch, a common unit needs a new piece of hardware, and there is a problem in terms of a mounting space and a mounting cost as well.

This method needs an addition of functions to the adapter (the problems in terms of mounting is smaller than a change in the common unit), and, as in the example of architecture shown in FIG. 2, there exists the problem in terms of the mounting space and the mounting cost.

Further, both of the adapter at an ingress for the packets and the adapter at an egress for the packets terminate the IP / MPLS, which is redundant control.

This method needs an addition of functions to the adapter (the problems in terms of mounting is smaller than the change in the common unit), and, as in the examples of architecture shown in FIGS. 2 and 3, there exists the problem in terms of the mounting space and the mounting cost.

To be specific, the label distribution protocols of both of hop by hop routing and Explicit Routing are incapable of indicating an intra-system specified adapter or port, and it is therefore unfeasible to set the LSP in which the specified adapter of the egress node is a terminal.

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