Talk:Classless Inter-Domain Routing
Prefix/suffix
I'm not quite sure here, but shouldn't "prefix" be replaced with "suffix" instead? --Maik
I think the usual terminology is prefix, since you route packets destined for 193.137.7.30 (for example) through the shortest path to the 193.137.7/24 prefix (which itself is aggregated and reachable through the 193.136/15 prefix (which is composed of the 193.136/16 prefix and the 193.137/16 prefix)).
The term prefix makes sense when you consider how the netmask is expressed in binary Robertbrockway 04:40, Apr 18 2005 (UTC)
I added a new diagram which should help clarify this.
Confusion
How in the heck did I interpret 4 minutes as 3 months??!? - Lucky13pjn 19:48, Mar 14, 2005 (UTC)
Example
The example about the /22 mask lists a Class-C address (192.168.0.0) but the default mask for Class-C is 255.255.255.0 or /24. I thought that you could only add ones bits to the default mask, not take them away. Wouldn’t a /22 mask have to be associated with a Class-A or B address?
This is the example given:
“192.168.0.0 /22 could be written 192.168.0.0 255.255.252.0”
Should it have been something like:
“172.168.0.0 /22 could be written 172.168.0.0 255.255.252.0”
--addnet 18:51, 23 July 2005 (UTC)
The restriction on taking bits away from the default mask only applied in the classful networking scheme. Classless routing is just what its name implies — you really don't have any restrictions anymore on what can be done to a "class A" or a "class C" address. With the exception of class D/E, the entire address space is now administered uniformly throughout. So there are no more "classes". Really.
Origins of CIDR
The first person to suggest using a net-mask to cover a group of classful networks (as opposed to subnets of a single classful network) was Carl-Hubert Rokitansky (affectionately known as "Roki" to all :-), in his "Cluster Networking" proposal (which long predated CIDR). (See this message and this reply to the internet-history mailing list.)
I had thought for a long time that there were no original documents on line for this proposal; web searches revealed nothing. However, I have just discovered that the online copy (large [[Portable Document Format|pdf] file) of the Proceedings of the '1st' IETF (there was actually at least one earlier one) includes a copy of Roki's handwritten slides on the matter, on pp. 45-61 (pdf page numbers). Just noting this here for informational purposes! Noel (talk) 16:11, 16 September 2005 (UTC)
Order, Order
I like the way you use a notation ie : " ... sixteen contiguous /24 networks ... " which is meaningless until you read later what the / means. Maybe you could assume the reader is new to the ideas of Classless Inter-Domain Routing, which is why he/she came to the page.
Similarly " ... The class, and hence the length of the subnet mask ...", before explaining what a subnet mask is. Very odd. I assume you are writing this for the people who already know it all, and just need a reminder?
Point taken. I think it's better now.
External links
There are plenty of online network calculators, and the two ones in the external links are quite limited in functionalities. How about adding this one. --Olivier Debre 07:45, 14 April 2006 (UTC)