This article currently contains strange paragraphs like

"A network mask, also known as a subnet mask, netmask or address mask, is a 32-bit bitmask used to tell how much of an IP address identifies the subnetwork the host is on and how much identifies the host."

Which is, of course, completely false in the general sense. Has the author not heard of IPv6 for example?

... which raises this question: Should this article really have anything to do with specific protocols, or should it just be an explanation of the term subnetwork with pointers to specific articles about IPv4 subnetting etc? We already have the IPv4 subnetting reference so that seems logical to me.

I would understand links to specific articles from here (such as one for IPv4 subnetworks and another for IPv6 subnetworks), but this seems a bit illogical. How about lifting protocol-specific material out to the revelant articles and pointing to them?

When e.g. IPv6 becomes more common, we'd otherwise have to include that one here as well to be consistent. It's of course another option, but again, we already have a specific IPv4 article for this -- why not use it better? Just a thought. :-) Jugalator 18:39, Aug 21, 2004 (UTC)

My primary reason for clustering them together was too many sub-stub-articles were created as a result, all of which were being pointed to by different articles, usually intending the same (IP specific) idea (Ex: Subnet, subnet address, subnetting, subnetwork, Classful network). I just took the vast (and often quite vague) array of IP-Specific Subnetting articles, and crammed them into one larger, easier to understand page.

The protocol-specific information could be difficult to remove, since different protocols handle subnetting differently (if at all), and reducing it to an explanation of what subnetting means, might again reduce it to a stubby dicdef.

Still remaining is a slew of other articles on the topic Internet_Protocol, IP address, IPv4 subnetting reference as well as IPv4, IPv4 address exhaustion and IP address allocation to boot.

We could simply rename the article to something like IPv4 Subnetting (IMHO adding the word "reference" may be a bit too verbose), make a redirect, and hope that someone working on one of the other (poor, abandoned) Network protocol pages (like AppleTalk, IPX or *gasp* Xerox_XNS) makes an appropriate disambiguation page if nessecary. Gamera2 06:28, 23 Aug 2004 (UTC)

Follow up

It seems as though IPv4 and maybe IPv6 (The same thing, minus a few extra features and changes for the sake of easy conversion), are the only two protocols that use "subnetting" in the flexable sense. All the other protocols (or at least the ones anyone knows anything about, can't speak for BanyanVINES myself), appletalk or IPX for example, don't seem to support any kind of masking past the pre-set network half of the address (for obvious reasons). If someone wants to put in a paragraph (or change the top one accordingly) to describe network/host halfs of logical addresses, then they're more than welcome to do that. Maybe add tidbits about how it's handled in IPv6, etc. - Gamera2 18:23, 13 Oct 2004 (UTC)

I started to try and clean this article up before I saw all this. I don't think we should have separate article for IPv4 and IPv6 subnetting - after CIDR they are now close enough in mechanism that there's no point. It would result in several tiny pages - something the Internet Protocol area has enough problems with already. IPv4 subnetting has a lot of history IPv6 subnetting doesn't have, but other than that they are now the same. If people want to split this page up, and have a page called "IP subnetting", that would be fine - but the remaining material on the subnet page would only be a few sentences.

As for the Internet Protocol mess, I've been working on cleaning individual pages up, but we could probably use some rational design of how many pages we're going to have, and what's in each. Do we want to start a WikiProject page to coordinate this, rather than having comments scattered here and there on various Talk: pages? Noel 02:57, 27 Oct 2004 (UTC)

Actually, I was looking for technical-specific information. Perhaps that could be added in a section, albeit probably very large? To help readers understand better, perhaps an example, one being an overview another technical, of information traveling through the internet as a user browses webpages through their home network (ie: through a router). Great article nonetheless! 68.3.8.223 15:51, 25 March 2006 (UTC)[reply]

In

"Network address 204.4.32.0 Decimal = 11001100.00000100.00100000.00000100 Binary"

shouldn't the last eight digits be all zero?

Snip 14:11, 9 September 2005 (UTC)[reply]

Yes. Noel (talk) 17:52, 19 September 2005 (UTC)[reply]

Putting this here as data for anyone who cares:

The first mention of subnets, in the sense of subdivisions of a classful network, that I know of in Internet documentation occurs in IEN-82, "LCS Net Address Format", from February, 1979. (MIT was using subnets some years before anyone else.) This subnetting scheme, as eventually adopted by the Internet, was more fully described by Jeff Mogul in RFC 917, "Internet subnets", in October 1984.

The notion of subnet masks has to be credited to Dave Moon, though, I think. Although the early LNI hardware supported masks, we didn't really think of using them in the protocol; it was Dave Moon, at an early meeting on an otherwise forgotten piece of technogical detritus named 'MUPPETS' (the name is a play on PARC Universal Packet) - an attempt to deal with the multiplicity of protocol suites inside MIT at the time - who made the mask suggestion at the protocol level, and it was carried forward to Mogul's paper. Noel (talk) 17:52, 19 September 2005 (UTC)[reply]

I consider myself fairly technically savvy, but I’m no network admin. I found this article is highly technical and presents more theory rather then explanations. I might suggest it’s a challenging for anyone to understand this who doesn't already have an extensive knoweldge of networking terminology. I found the external link to the about.com article far more effective at describing what subnetworking really is with better examples. --Trode 18:31, 1 December 2005 (UTC)[reply]

Sorry about that. I was trying to leave it pretty simple, but I'm sure it can be dumbed down some more. Taking too much away from the article would leave a lot of room for explanation, but simplifying the basics at the start would probably help. Strip away too many of the details and it becomes little more than an overglorified dicdef. Math articles tend to have the same problem. --Gamera2 20:59, 3 December 2005 (UTC)[reply]

I agree, Trode. I can't make head or tail of it. Maybe add more explanation 88.111.52.30 15:17, 29 December 2005 (UTC)[reply]

This article really needs more clarity. There is, for instance, no clear definition of what the subnet mask is or what role it plays in networking/ TCP/IP. Why are there only certain numbers allowed? How does it work exactly? The article assumes a certain amount of knowledge on behalf of the reader, which is fallacious encyclopedic practice.--Hieronymus 09:04, 20 April 2006 (UTC)[reply]

I agree it could be much clearer. I have an EE degree and do a bit of network administrating on the side, but still found this a very difficult read.—The preceding unsigned comment was added by 71.113.121.17 (talk • contribs) 06:51, September 28, 2006.

I also agree that this article needs some rewording and cleanup. Its certainly not very clear even for someone who knows what subnetting is and how it is done.--Crossmr 16:27, 28 November 2006 (UTC)[reply]

The current article says that The 127.0.0.1 Network ID is left out because it is designated for loopback and cannot be assigned to a network. Are there really not more reasons to be mentioned here? It looks very inefficient to take out 2²⁴ IP-adresses, and then use only one of them. Bob.v.R 09:03, 15 May 2006 (UTC)[reply]

127.* is loopback; I can't see any other reason if all the range already has a known and common meaning. Actually, it's not entirely true that only one of them is used. You can use whatever IP in the range to refer to loopback (and I guess using different IPs has some use). There're other inefficiences in the IP, so why not this one :P --Outlyer 17:48, 15 May 2006 (UTC)[reply]

In the example of the chapter "subnetworking concept" it says:

"Determining the number of hosts and subnets on a particular network is quite easy, if you know the subnet mask. Say you have the network address 154.4.32.0 with a subnet mask of 255.255.224.0. This network address can also be written as 154.4.32.0/19

Network address 154.4.32.0 (decimal) => 10011010.00000100.00100000.00000000 (binary) Subnet mask 255.255.224.0 (decimal) => 11111111.11111111.11100000.00000000 (binary) The subnet mask has 19 bits for the network portion of the address, and 13 bits for the host part.

2¹³ = 8192 possible subnets available according to RFC 1812, otherwise using the old RFC 950 standard the number of usable subnets is 6. This is due to RFC 950 (section 2.1, page 5) not supporting subnets with either all 1s or all 0s."

Shouldn't this be 2¹⁹? - Otherwise, an explanation of why a mask of 19 bits only gives us 2¹³ possible subnets would be nice. (Admitted - I did not read the RFC's, which is also why I didn't just start editing the article on my own, but I think, this explanation goes against a basic sense of math...? — Preceding unsigned comment added by 62.107.132.247 (talk • contribs) 18:46, 11 July 2006 (UTC)[reply]

The length of the netmask is 19 (out of 32), so the length of the network part if 19 and the host's is 32 - 19 = 13. Right?

Why ? I mean, why 3? Should we assume this is a class B (/16) network, and we're trying to fit that many /19 in it? So ?

Several people have been expressing concern that this was hard to understand. I've spent the last 90 minutes rewriting this article in, what I hope, an easier to understand method. I included some binary examples. I found that when I learned how to subnet seeing it as binary really made things easy for me to understand and grasp the concept. I've only copy edited it a small amount, so I'm sure it does require some of that. I've kept the links as I didn't have the time right now to go through them and make sure they all apply and I've kept a few of the paragraphs and one of the tables that was there before. I've tried to lay down a foundation of what a subnet mask is, what a network address is and how they work together. Any comments are welcome.--Crossmr 17:47, 28 November 2006 (UTC)[reply]

A graphic representation of relationships and source of the various variables representing a chunk of C subnets

"chunk" is an unprofessional term being used here, and that wording is confusing for someone who doesn't already understand subnets, IPv4 and all the terms associated with it. Referring to it as Class C makes it more clear what is being talked about. The other wording:

A graphic representation of the possible lengths of subnets in a class C network

Is a more accurate and concise description of what it is. They are indeed possible lengths, its possible you could have a subnet mask of any of those lengths in a class C network. It will certainly be one of them, but it its possible to be any of them. The image is certainly educational, which is why I didn't remove it, but it needs to be described better.--Crossmr 16:56, 30 November 2006 (UTC)[reply]

I agree that my description suffers from substandard wording but it does so for the higher purpose of acuratelly describing the image, to work on a better description i would like to highlight the features of the image that need to be reflected in it's description.

1. it represents the last of the 4 octet blocks forming ALL of the 32 possible CIDR blocks , all 4 blocks being variations of a base data which is represented here , half of the C class (hence chunk and C)
2. it depicts the way one value can be extracted from another and where do all the values come by color code and formula's in the header (hence relation and source)

i have nothing against anyone crafting a description to both reflect these and be fluent--Mancini 17:28, 30 November 2006 (UTC)[reply]