""Michael L. Williams"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... snip a bit > 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.....
CL: having done a few technical reviews for various levels of publication now, I have a comment or two. Some publishers are better than others, but all are under severe pressure to get books to market, to cut the time from initial proposal to distribution to the absolute minimum. CL: There was one publisher who expected me to turn things around on a dime. The editor with whom I worked was furious that it took me more than an hour to rubber stamp what the author had written. The attitude certainly explains some of the idiot mistakes in a series of books by someone whom all of us on this list have used with great success in our certification pursuits. CL: there was another publisher who contracted me at the absolute last minute, and when I returned my review with a list of errors I had found, told me that it didn't matter - the work had already gone to press. that since this was for CCIE level certification, it would be a good exercise for the CCIE candidates to discover the errors for themselves. CL: I'm currently reviewing a book for a publisher who seems to appreciate my efforts to be thorough, and with an author who takes criticism well. As a result, when the book is published you will not be reading about how GRE is used in conjunction with L2TP to create secure VPN tunnels. Nor will you be reading what amounts to incomprehensible gibberish in certain places. The author knows his stuff in certain areas, but is unsure in other areas. The point being that the author wants to write a good book, and is willing to take avice on how to improve his writing, and the publisher wants a good book and is willing to accept that it takes a bit more time to create one. CL: Based on previous experience, I think it is safe to say that these attitudes are the exception, and not the rule. > > > 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=45039&t=44649 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
