Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1997-12-02
2001-08-14
Olms, Douglas W. (Department: 2732)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S400000
Reexamination Certificate
active
06275492
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to systems for routing data through one or more networks. More specifically, the invention provides a system for routing data packets through a network using router identification information contained in the data packets.
2. Background
Data communication networks may include various nodes, routers, switches, hubs, and other network devices coupled to and communicating with one another. Data is communicated between network devices by utilizing one or more communication links between the devices. A particular data packet (or data cell) may be handled by multiple network devices and cross multiple communication links as it travels between its source and its destination. Additionally, multiple networks may be coupled to one another by common network devices or common links.
Various protocols may be used to communicate routing information through a network. One type of protocol is referred to as a link state protocol, in which each node in the network knows the network topology such that the node can calculate routes through the network using the known topology. The link state information is distributed to network nodes using a series of Link State Advertisements (LSAs) originated by routers and other nodes in the network. For example, a router may advertise LSAs into the network area in which the router resides. These advertised LSAs may indicate that the router has connections to one or more network nodes. These LSAs are received by other routers and nodes in the network. Thus, the other routers and nodes learn of the connections described in the advertised LSAs. All routers in the network may generate and advertise similar LSAs.
Since each router “learns” the network topology by receiving various LSAs, each router is capable of independently calculating routes through the network. Typically, when a router forwards a packet, the router determines the best “next hop” router by consulting a routing table maintained by the router. Known routing systems use the data packet's destination address as the lookup key in the routing table to determine the next hop router. Since the exact destination address may not be stored in the routing table, the router selects the closest match. This type of matching may be time consuming, especially if the routing table has a significant number of entries.
Another routing approach, referred to as “tag switching” (or “tag routing”), forwards data packets based on “tags” inserted into the data packet rather than based on a packet's destination address. The router then uses a “tag table” to lookup the tag. Each tag in the tag table is bound to a route. Each tag-route pair must be distributed to other nodes in the network before the “tag switching” system can be used. This binding of tags and routes, and the advertisement of the tag-route pairs may take additional time, thereby delaying the transmission of network data. Additionally, each change in a tag-route pair must be advertised to other nodes in the network.
It is therefore desirable to provide a system capable of performing tag switching, but that does not require the binding of tags and routes, and does not require the advertisement of the tag-route pairs to other nodes in the network.
SUMMARY OF THE INVENTION
Embodiments of the present invention provide a system for routing data packets through a network using router identification information contained in the data packets. The use of router identification information does not require the binding of a tag to a route and does not require the advertisement of tag-route pairs. Instead, the tag switching system of the present invention uses the router identification information as a tag when switching or routing packets.
An embodiment of the present invention provides a system for routing data through a network by determining whether router identification information is associated with the data. The system identifies a next hop router from a router table if router identification information is associated with the data. The system identifies a next hop router from a routing table if router identification information is not associated with the data.
Another embodiment of the invention determines whether a match exists between entries in the router table and the router identification information when identifying a next hop router from the router table.
In a particular embodiment of the invention, the data is contained in a data packet and the router identification information is contained in the data packet.
One embodiment of the invention provides a network device having a routing table, a router table, and a routing engine coupled to the routing table and the router table. The routing engine is configured to forward data toward a destination in response to router identification information associated with the data.
REFERENCES:
patent: 5675741 (1997-10-01), Aggarwal et al.
patent: 5881246 (1999-03-01), Crowley et al.
patent: 5917820 (1999-06-01), Rekhtov
patent: 5951649 (1999-08-01), Dobbins et al.
patent: 5987521 (1999-11-01), Arrowood et al.
patent: 5999536 (1999-12-01), Kawafuji et al.
patent: 6069895 (2000-05-01), Ayandeh
patent: 6078963 (2000-06-01), Civonlav et al.
Blakely , Sokoloff, Taylor & Zafman LLP
Nortel Networks Limited
Olms Douglas W.
Vanderpuye Ken
LandOfFree
Method and apparatus for routing data using router... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for routing data using router..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for routing data using router... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2550460