Packet filtering method

Details Packet filtering method Packet filtering method

1999-05-20

2001-08-07

Chin, Wellington (Department: 2664)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

Reexamination Certificate

active

06272133

ABSTRACT:

FIELD OF THE INVENTION
The present invention is related to packet filtering. More specifically, the present invention is related to packet filtering utilizing a table comprised of entries wherein redundant entries have been removed.
BACKGROUND OF THE INVENTION
In packet filtering, information for filtering the packet is commonly stored in tables. This information is searched to effect the packet filtering. The more information that must be searched, the longer the filtering takes of the packet. The information in tables is often full of redundancies. If the redundancies could be removed, less memory would be necessary to store the information, and the speed of the search for the filtering would increase.
SUMMARY OF THE INVENTION
The present invention pertains to a method of filtering packets having a class. The method comprises the steps of accessing a table comprised of entries that include an indication to which class a given entry applies. Then there is the step of searching the entries until an entry whose class indication corresponds to a current class of the packet. Next there is the step of forwarding a frame associated with the entry whose class indication corresponds to the class of the packet.
The present invention pertains to a data communication apparatus. The apparatus comprises a mechanism for routing or switching packets. The apparatus comprises a memory having information for routing or switching the packets. The apparatus comprises a mechanism for compaction of information in the memory which removes redundancies in the information.
The present invention can be utilized with any data communication device where packet switching/routing is performed. This invention addresses memory space concerns. Traditional packet filtering utilizes software implementations that have limited performance. Hardware-based filtering solution may require either CAM memories (expensive and of limited size) or very large search spaces. Frequently combining several packet header fields leads to very rapid growth of the number of connections.
The invention allows combining several independent search steps that result in a single compound operation that allows implementation of packets filtering. Such packet filtering is frequently required for network traffic monitoring and management and often requires fine granularity of the switching/routing decision. In practical applications several separate fields of packet headers are required to fully specify the switching/routing decision.
The present invention provides many advantages, including: (1) ASIC-based all hardware implementation is possible; (2) small size of memory space allows cost effective implementation with standard parts; and (3) small number of memory accesses per processed field allows very high performance (millions of packets per second) with readily available standard components, to name but a few. Other advantages will be recognized by one of ordinary skill in this art upon review of the description below of the accompanying figures.


REFERENCES:
patent: 4989134 (1991-01-01), Shaw
patent: 5610905 (1997-03-01), Murthy et al.
patent: 5805808 (1998-09-01), Hasani et al.
patent: 5918052 (1999-06-01), Kruskal et al.
patent: 5951651 (1999-09-01), Lakshman et al.

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