First let me say that I was looking for a book to recommend to a friend, and I picked up this same book in the store and thumbed through.... I actually happen to stop on the part where it talked about how a switch (bridge) builds a routing table etc....... I put the book down, pointed at it, and told my friend "Don't by this book!" I am appalled at what passes for techincal books (I guess I'm more sensitive about networking topics)..... but in the technical field, one must be careful about the terms they use because they can mean different things..... packet -vs- frame, etc.....
> Cisco calls the mac table a "content addressable memory" table. without > spending more time than I have at the moment, I can't find a history on CCO > as to why they do this. Here is some info I found on CAM....... basically, you can use the data to find itself in memory (as opposed to having to know it's address in memory)...... (all of the following info is from various web pages found through Google) Content-Addressable Memory (CAM): In this information-handling model, each possible piece of information has one and only one possible storage location. The data is its own key. It is important to differentiate CAM from a hash key or traditional index. With conventional indexing schemes the data content is used with a hash or index to produce the address location of the data. The address has no real or direct relationship with the information contained in the data. With CAM, the data describes its own storage location. This also means all like data will always be found close together in the physical data structure. There is a direct relationship between the information in the data and its location in the physical data store. In a symbolic system information is stored in an external mechanism. In the example of the computer it is stored in files on the disks. As the information has been encoded in some form of file system in order to retrieve that information one must know the index system of the files. In other words, data can only be accessed by certain attributes. In a connectionist system the data is stored in the activation pattern of the units. Hence, if a processing unit receives excitatory input from one of its connections, each of its other connections will either be excited or inhibited. If these connections represent the attributes of the data then the data may be recalled by any one of its attributes, not just those that are part of an indexing system. As these connections represent the content of the data, this type of memory is called content addressable memory. This type of memory has the advantage of allowing greater flexibility of recall and is more robust. You can compare CAM to the inverse of RAM. When read, RAM produces the data for a given address. Conversely, CAM produces an address for a given data word. When searching for data within a RAM block, the search is performed serially. Thus, finding a particular data word can take many cycles. CAM searches all addresses in parallel and produces the address storing a particular word. You can use CAM for any application requiring high-speed searches, such as networking, communications, data compression, and cache management. Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=44997&t=44649 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
