I've always liked hex myself. A hex mask of FF.FF.F8.00 can be written as FFFFF800 and still mean the same thing. You obviously can't do that with 255.255.128.0 (255.255.128.0 != 2,552,551,280). While binary works the same way as hex in this manner, it is much to long for my tastes. Plus, hex is used a lot in programming languages when using values in bitmasks, so I'm more familiar with it. Also, there are only 5 hex numbers that you need to memorize for masks, F 0 8 C and E.
Fred Reimer - CCNA Eclipsys Corporation, 200 Ashford Center North, Atlanta, GA 30338 Phone: 404-847-5177 Cell: 770-490-3071 Pager: 888-260-2050 NOTICE; This email contains confidential or proprietary information which may be legally privileged. It is intended only for the named recipient(s). If an addressing or transmission error has misdirected the email, please notify the author by replying to this message. If you are not the named recipient, you are not authorized to use, disclose, distribute, copy, print or rely on this email, and should immediately delete it from your computer. -----Original Message----- From: Howard C. Berkowitz [mailto:[EMAIL PROTECTED] Sent: Tuesday, September 09, 2003 11:32 PM To: [EMAIL PROTECTED] Subject: RE: Please Help - CIDR - How the bits work [7:75050] At 10:36 PM +0000 9/9/03, Dom wrote: >Fred, check out the archives for Howard's piece on the difference >between 'Rocket Science' and 'BGP' when at NASA. > >Best regards, > >Dom Stocqueler >SysDom Technologies >Visit our website - www.sysdom.org Seriously, I've fought a battle for many years with Cisco Training. I believe the fundamental problem they _create_ is insisting on teaching classful and dotted decimal notation first. When I've given private classes -- ICRC, the older RSC, etc. -- I always began discussing addressing in binary, got people used to the idea of prefix length, then introduced dotted decimal as a means of representation, and then introduced classful addressing as a historic concept. Students were always able to go right into classless routing without any trouble. There are some nice examples in RFC 1878. RFCs 1517-1520 give the main background, although there are some earlier papers on "supernetting". With all mercenary disclaimers, I also recommend my book, _Designing Addressing Architectures for Routing and Switching_, and my recent IPv4/IPv6 tutorial on Certification Zone. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=75185&t=75050 -------------------------------------------------- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
