Talk:Classful network

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Contents 1 switch or router? 2 Loopback 3 the zero address range 4 I'm afraid of Americans 5 What? 6 192.168 Class 7 End of Class A range wrong?

[edit] switch or router?

the edit made on this date 21:58, 11 September 2006 203.145.184.222 seems awry.

they changed switches to routers and it seems to have stuck. note that they also changed the year from 1982 to 2006 etc etc.

Yeled (talk) 02:26, 24 January 2008 (UTC)

[edit] Loopback

I'm pretty sure 127.0.0.1 is the normal loopback address. Any ideas on resolving this? --217.204.169.167 15:56, 14 Mar 2004 (UTC)#

You are correct: 127.0.0.1 is the normal loopback address. However, it's the lowest usable address in the classful 127.0.0.0/8 loopback network which is reserved for local loopback, assuming the old rules of not using the all-zeros address (which requirement has been relaxed for CIDR). So both statements are valid. -- The Anome 16:02, 14 Mar 2004 (UTC)

Does anyone know what the Class E addresses (240.x.x.x-254.x.x.x) were reserved for? Experimental is what I seem to have found..anyone know what was meant by this?--Kcbnac 06:32, 13 October 2005 (UTC)

As a participant in IETF addressing work, I've never heard anyone explain the purpose of Class E, but there are so many implementations that would reject it as an invalid range, no one has ever really tried to make it work. Hcberkowitz 22:53, 25 June 2007 (UTC)

Not sure if I am right and guess this is the right place to bring it up, but I thought a class A address range ended at 127.0.0.0 in (ddn) not 126.0.0.0 as stated in the article?

[edit] the zero address range

An expansion of the purpose of the zero-address range by someone more in the know than I would be greatly appreciated. -- Jon Dowland 16:40, 16 January 2006 (UTC)

If you are speaking of subnet zero, that's an artifact of classful routing, in which you don't always have the subnet mask available but have to infer it from the first few bits. For example, without a subnet mask or CIDR length prefix, is 10.0.0.0 a "class A network", or is it subnet zero of a 24-bit prefix? You can't tell by looking at the address alone.

With CIDR notation, the first is 10.0.0.0/8, but the second is 10.0.0.0/24. There's no ambiguity for the all-zero subnet if you always know the mask. Hcberkowitz 22:51, 25 June 2007 (UTC)

[edit] I'm afraid of Americans

Ok, fair enough, Americans built the Internet alone and they believe they own it (built it alone after their military kids gave it to the tech and sci guys,because they didn't even thought to ask European or Asian cooperation to begin with), as they believe they own the world. But WTF why it would be so difficult to them to force their large companies to give up millions of unused IP numbers? Selfish Americans, no gou, naughty, naughty people... [Anonymous] —Preceding unsigned comment added by 201.19.199.6 (talk • contribs)

I suggest you become a bit more familiar with the history of the Internet. In point of fact, the military proper had relatively little to do with the original development of the ARPANET and Internet, but provided funding to academic research organizations, including European and Asian organizations. I suggest you look at the rules at which IP addresses were originally allocated, and the present roles of the continental Regional Internet Registries, such as RIPE-NCC, APNIC, LACNIC, AfriNIC, and yes, ARIN. You seem to have an idea that there is some American organization that can give and take IP addresses away. It's not. Certain companies and universities, involved in research early on, did get large blocks. Some, such as Stanford University, returned their original large space, but at their own initiative. One of the reasons the allocation was wasteful is a point of this article: classful addressing is inefficient, but that's how initial allocations were made. Techniques such as Network Address Translation didn't exist for the ARPANET.

There are perfectly valid technical reasons to have blocks of registered addresses that are not accessible in the public Internet, such as for international telecommunications and financial organizations that are sufficiently large to need a block they can allocate to new members, without fear of duplication.

Classless Inter-Domain Routing (CIDR) enormously increased address allocation efficiency. In any event, whether or not organizations give up IPv4 address space, there are good reasons to go, systematically, to IPv6 addressing. The obsolescence of the IPv4 address space is not merely a matter of exhaustion, but of issues such as aggregation. Hcberkowitz 22:44, 25 June 2007 (UTC)

[edit] What?

Say.. this article needs a couple of introductory sentences explaining what the hell it is about. As a general, non-tech, liberal arts reader, I have no idea what any of this article means. I understand that the more technical stuff is going to be incomprehensible to me, but perhaps just one or two sentences at the beginning to put it into context or something? Torgo 04:47, 31 March 2007 (UTC)

[edit] 192.168 Class

What class is the 192.168 subnet? On the special ranges table it lists it as a class C with a /16 mask, while the "Class ranges" table says that a /16 netmask is a class B. Which is it? Same goes for 192.18, I guess... --Poromenos 19:43, 23 June 2007 (UTC)

With due regard that classes are obsolete, 192/8 (in current notation) or 192.x.x.x are class C. 192/8 is also called the traditional Class C space, or, among service providers, "the swamp". At one point, before CIDR, addresses in 192/8 took up half the global routing table, and prefixes of /24 or longer (i.e., mask 255.255.255.0, 255.255.255.128, etc.) took up half of 192/8. The latter part of the "swamp" was called the "toxic waste dump" in CIDR slang.

192.168/16 is designated as private address space, not routable on the Internet. 192.0.2.0/24 is reserved for specialized testing.Hcberkowitz 22:48, 25 June 2007 (UTC)

While 192.168/16 appears to be a Class B subnet, it is actually a collection of 256 separate Class C subnets. The notations 192.168/16 is therefore somehow inaccurate, the correct approach would be to list the 256 subnets indivdually (192.168.0/24, 192.168.1/24, 192.168.2/24, ..., 192.168.254/24, 192.168.255/24).

This set of subnets was useful before CIDR appeared. With CIDR, the 192.168/16 range can indeed be used like a Class B subnet or whatever subnet sizes the user requires.

Before CIDR, some devices had hard-coded subnet class assignments. So they regarded 10/8 always as Class A, and it was not possible to split this subnet into smaller subnets. So 192.168/16 was created, for people who needed a number of small separate subnets. --80.134.14.19 (talk) 15:25, 9 April 2008 (UTC)

[edit] End of Class A range wrong?

Shouldn't the end of the Class A range (under "Useful tables") be 127.255.255.255 instead of 126.255.255.255? --195.37.212.230 (talk) 10:08, 21 January 2008 (UTC)

Oops.. 127.* is a special address range. --132.199.235.61 (talk) 17:28, 21 January 2008 (UTC)

The correct Class A range is 0.0.0.0 to 126.255.255.255, 127.0.0.0 to 127.255.255.255 is reserved per RFC 1700. —Preceding unsigned comment added by Phidjit (talk • contribs) 20:31, 12 March 2008 (UTC)