Talk:Classful network

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)

I'm afraid of Americans

Don't be, it is the American Government you need to worry about.[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)

I have to chime in regards to the 2007 reference to ipv6. It's 2011 and we don't have anymore IPV6 now than we did in June 25 2007. I also don't understand how ip numbers that aren't accessable by the internet are useful to banks and other sectors. Bank of America has 5 or so million and I would entertain anyone to explain the need for that. Is someone going to say all the atms need an ip or 2? I also don't know how accurate the statement saying "nat wasn't around" is. While the term nat may not have been around the technology needed for deployment would of been no harder back then so im sure they did have it to some regard.

We might have large numbers of ipv6 being assigned to isps and organizations but none of it is being used in a production setting. I have it with hurricane electric and their ipv6 won't talk to level3's. What good is ipv6 when it won't talk to it's neighbor? All the hype and money he.net invested in getting ipv6 out there apparently didn't also go to their peering relationships to make sure their ipv6 was of any use outside of their network. Woods01 (talk) 22:07, 20 March 2011 (UTC)

My workplace purchased a block of ipv6 a few years back now, and we show no signs of using it any time soon. This is 10 years after the last comment about not using it in a production setting.--Sombodystolemyname (talk) 00:48, 26 October 2021 (UTC)

Suggesting that some orgs should give up addresses is not the same as saying that IPv6 is a bad idea. If the exhaustion of addresses is occuring more rapidly than IPv6 testing and deployment, then adjusting some of the wildly inefficient allocations seems like a natural way to bridge the gap. —Preceding unsigned comment added by 204.87.16.4 (talk) 10:43, 17 March 2011 (UTC)

Lead

Normally I'd just do a little gnoming on this, but I'm not sure I understand the subject sufficiently to be certain I'm not mistaken... "defined a different size or type (unicast or multicast) of the network."

Shouldn't "the" be removed from that sentence, or else the "defined a different size or type" be changed to "defined the size or type"? —Preceding unsigned comment added by Dr.queso (talk • contribs) 04:21, 30 June 2010 (UTC)

I agree the wording of the lead was somewhat confusing, and I have reworded it. Part of that was to change the tense from "defined" to "defines" because although classful networks are no longer used on the Internet, and indeed are probably extremely rare if not non-existent, there is nothing to stop someone setting up a classful network, so strictly past tense is clumsy and inaccurate. Johnuniq (talk) 07:20, 30 June 2010 (UTC)

Why does Cisco still care?

As I study for my CCNA exam, after many years of doing this sort of stuff, I am repeatedly bumping on the fact that Cisco Certifications still care about classful addressing, and I just can NOT figure out why. Sure, it's an interesting historical note, but WHY do they insist on you learning about it? It seems a worthwhile note to add here, if anyone has any clue. Jbsegal (talk) 17:50, 27 September 2020 (UTC)

I agree - I use it absolutely never in my job.--Sombodystolemyname (talk) 00:44, 26 October 2021 (UTC)

It's also required knowledge in CompTIA's Network+ exam. — Preceding unsigned comment added by 38.147.234.117 (talk) 22:02, 28 January 2022 (UTC)

ARPANET network number

the most significant eight bits of the 32-bit IPv4 address was the network number field

As a consequence of this architecture, the address space supported only a low number (254) of independent networks.

If I have eight bits in the network number field, I'd expect to get 256 possible networks out of that. Were there two special network numbers that couldn't be assigned to networks? Similar to the network ID and broadcast address in the host part of IPv4? Mb720 (talk) 00:34, 16 December 2023 (UTC)