1. Field of the Invention
The present invention relates to content addressable memories, and more specifically, to content addressable memories having bandwidth allocation for use in high speed data communication networks.
2. Brief Description of the Related Art
Modern communications systems transmit data over digital networks. System resources are finite, so allocation of those resources becomes necessary. For example, system capacity limitations may restrict the amount of data that can be transmitted by the network, or a user may wish to give priority to certain categories of data over others.
Practically all digital networks make use of some form of packet or block type data format to dynamically route data packets or blocks through the network. The data contained in the packets can be categorized in various ways, including type of packet, packet content, size, creation date, and urgency of delivery, for example. Depending on the purpose of the communications system and the preferences of the user, it may be necessary to limit or expand the amount of bandwidth to be allocated to a particular category of data.
Content addressable memories (CAMs) are used in communications systems as search engines for routing paths in data network routers and switches. The packets being routed can be viewed as belonging to a particular category. Typically, a CAM issues a single search result that is independent of a packet category. Consequently, it is necessary for the user to handle bandwidth allocation, for example, by discarding search results for certain categories. A significantly more efficient way of utilizing a CAM as a search engine is needed.