[ Date Index ] [ Thread Index ] [ <= Previous by date / thread ] [ Next by date / thread => ]
On Wed, 12 May 2010 11:05:41 +0100 (BST) Gordon Henderson wrote: > On Wed, 12 May 2010, Grant Sewell wrote: > > > On Wed, May 12, 2010 at 8:57 AM, Gordon Henderson > > <gordon+dcglug@xxxxxxxxxx> wrote: > >> On Wed, 12 May 2010, James Fidell wrote: > >> > >> At least 15 years... > >> > >> I was working for an ISP in 1995 when the great debate was kicking > >> off and CIDR was "invented" Lots of routers back then (ie. cisco) > >> were buggy as they had all the netmasks for the old "Class A,B,C" > >> networks hard-wired into them. We were using BSD boxes as routers > >> back then, so didn't really have any issues with the > >> "experimental" /16's RIPE gave us (out of Class A space) to .. > >> er .. experiment with. (And people today still talk about Class A, > >> B, .. networks )-: > > > > Perhaps CIDR should be covered sooner but it still useful for > > students to learn about it in stages - start with classful and get > > 'em to setup a 2-router configuration with Class A on the LAN side > > of Router A, Class B between the 2 routers (ie pretend WAN side) > > and Class C on the LAN side of Router B - they can then easily see > > the differences between the 3 sections and should be able to > > visualise the process of data flowing from Router-A-LAN to > > Router-B-LAN via the pretend WAN. > > I disagree. In these enlightened days, classed addressing is dead and > should not be mentioned at all other than in history lessons. > > No-one uses classed addressing in todays real-life Internet. Networks > are just that - a network base and a subnet mask, or a /prefix. > Nothing more, nothing less. Anyone coming to me looking for a job and > asking about what Class C networks I have would be shown the door. > > Stop teaching classed network addressing. They went out of fashion 15 > years ago. > > Gordon Token Ring is also a dead technology, but it is still taught so that students have a grounding in *concepts* other than CSMA/CD. Just because something is dead doesn't mean it is not *useful* to learn about it - either from a historical point of view, to introduce concepts or to stagger the learning process. I still teach classful addressing for IPv4 - Class A, B, C, D & E. It would be kinda hard to explain why the multicast address ranges begin with 224 and are called "Class D" addresses without visiting classful addressing. A little way down the line I introduce CIDR and related topics and not one student has become confused by it. Grant. -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html