Talk:Application layer

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why bittorrent is here? —The preceding unsigned comment was added by 200.77.115.58 (talk • contribs) .

Because BitTorrent is an application layer protocol. — EagleOne\^Talk 18:49, 10 February 2006 (UTC)Reply

But then some other protocols such as eD2kFTP have to be added too, isn't it?

No, they are just examples, not a complete list.

why MIME is here? I understand MIME as the presentation layer format (or message representation protocol(s)). Also the OSI Model article puts MIME on the presentation layer. — MaBe\^Talk 16:03, 27 July 2006 (UTC)Reply

It is my understanding that many of the Application Layer Protocols actually perform the services of the Application, Presentation and Session layers of the OSI model. This is why the DoD model lumps the layers together. Someone correct me if I'm wrong. Rsduhamel 23:32, 18 September 2006 (UTC)Reply

Sounds correct to me, layers 5,6 and 7 are somewhat blurred. For example SIP (Session Initiation Protocol) should arguably be represented at layer 5, not at layer 7 as it is here.

jsut wanted to make note of a factual error....there aren't seventeen layers in the OSI model...only seven. Just thought someone might want to correct that.

66.129.232.2 16:12, 12 March 2007 (UTC)Marc M.Reply

^{Application Layer: Factual error}

there are only 7 layers in the OSI model. Just posting so that someone can correct this.

66.129.232.2 16:14, 12 March 2007 (UTC)Marc M.Reply

Just wanted also to ask, why MIME is here? For me it is one level higher. —Preceding unsigned comment added by 91.213.255.7 (talk) 00:44, 10 March 2011 (UTC)Reply

Following the link "application protocol" in the "Lightweight Directory Access Protocol" article redirected me to "Application layer". Am I to take that as a clear statement that "application protocol" is always synonymous with "application layer protocol"? If so, such a clear statement should be made explicitly. If not (for example, in reference to a protocol used by an application having nothing to do with communications), the redirect is simply wrong. Either way, simple redirection without explanation seems like the wrong way to go. Unfree 13:13, 1 December 2007 (UTC)Reply

Layer 7 in OSI is not layer 5 in TCP/IP!! Please, someone correct this.
One example: RDP (presentation layer 6 OSI / application layer 5 TCP/IP).
(also, I restored good ver. of page, just FYI)
G.

I see problems with the following entries that I think do not belong in layer 7:

(other person) : I'm a student electrical engineering just learning about DHCP so i was a bit confused when i saw this protocol in layer 7. — Preceding unsigned comment added by Louis Van hunsel (talk • contribs) 09:48, 18 January 2022 (UTC)Reply

• Basenet

(what's this? article successfully prodded in 2007)

• BOOTP, Bootstrap Protocol

(layer 3 management protocol)

• DHCP, Dynamic Host Configuration Protocol

(layer 3 management protocol)

• H.323, Packet-Based Multimedia Communications System

(a protocol stack ranging all the way down to MAC sublayer of layer 2)

• LDAP, Lightweight Directory Access Protocol

(layer 5)

• MIME (S-MIME), Multipurpose Internet Mail Extensions and Secure MIME

(layer 6, as mentioned above a year ago)

• NFS, Network File System

(layer 5)

• SIP, Session Initiation Protocol

(layer 5)

• VoIP, Voice over Internet Protocol

(certainly has a layer-7 component but reaches down to the LLC-sublayer of layer 2)

• VTP, Virtual Terminal Protocol

(Provides services to the application layer, hence likely layer 5)

• X.500, Directory Access Protocol (DAP)

(Provides services to the application layer, hence also likely layer 5)

I shall wait for a couple of days for complaints, an then I'll remove (or move) those entries. --Pgallert (talk) 13:31, 23 January 2009 (UTC)Reply

The article does not discuss Layer 7 protocols, but Application Layer protocols in general. Since the article is not model-specific to OSI or TCP/IP, most of these should be restored. Separate articles or separation into sections may be appropriate however. Kbrose (talk) 16:29, 29 January 2009 (UTC)Reply

_sigh_ That's why I put it on the discussion page a week ago... Still DHCP and BOOTP are not on the application layer of either model, and still H.323 is a set of protocols of which only some are on AL.

Now, what can be done? split into separate entities like

1. Application layer (OSI model)
2. Application layer (TCP/IP model)
3. Application layer (disambiguation)

Might be the only option as there are more notable models around, eg ATM. --Pgallert (talk) 07:29, 30 January 2009 (UTC)Reply

Application layer protocols convert user info into data. DHCP and BOOTP do not do that, they are on the network layer of OSI and TCP/IP models. See e.g. Forouzan, Behrouz A (2007). Data Communications and Networking. McGraw-Hill. pp. 612–620. ISBN 007-125442-0. --Pgallert (talk) 08:40, 3 February 2009 (UTC)Reply

Unfortunately, your reference is wrong. This text's discussions has other defects as well and is not a reliable source (however, it is ok to quote 'wrong' sources and state the controversial nature of a topic) Nowhere is the application layer (at least in TCP/IP) defined as converting specific types of info into data. What do those terms mean anyways: "user info" and "data"?. The only distinction that OSI makes is the separation of data w/r/t to the functions of the presentation and session layers. But obviously this has caused much confusion already, because in many instances this distinction is very murky and controversial. The extensions of the original OSI model do consider a network management section in the network layer, but TCP/IP has nothing like that. There is nothing special about providing boot information to a system, it's an application and the delivered info is 'user data' like any other application. Kbrose (talk) 15:03, 3 February 2009 (UTC)Reply

For the distinction of information and data, see the respective articles on WP. The difference is the abstraction levels. For a definition of the Application Layer in TCP/IP, see RfC1123, for the other layers RfC1122. And no, DHCP does not deliver user data. There is a difference between management protocols and application protocols. The management protocols do not easily fall into any layer, but if they must they are commonly sorted into the layer they manage, except by you. Have fun. The payload defines layering, not the transport mechanism.

It would of course have been nice had you come forward with any source to back your view of the matter instead of repeatedly reverting me because you think I'm wrong. Every text book has defects, and the one by Forouzan is (in my personal, utterly inferior view) not the worst of them all. But never mind, I will now step aside from this discussion as it seems I must first correct your misconceptions before I can correct the article itself, which is neither my intention nor apparently in my power. While I do not match his acumen, I now understand what frustrated Howard Berkowitz. --Pgallert (talk) 09:48, 4 February 2009 (UTC)Reply

yes, you do have the source of definition of the TCP/IP layers correct, which are already quoted in almost all relevant articles here and which support this model. BOOTP is specifically mentioned and it is not placed in the Internet Layer, but grouped as a support protocol discussed in the same context as application protocols, otherwise it would have been in RFC 1122, and not in RFC 1123. There is no intent evident in any of the RFCs to support the concept of management layers or sublayers. DHCP and BOOTP do not manage any layer in particular, in fact they (DHCP in particular) go far beyond just providing IP addresses. TCP/IP defines the layers not by data or payload type, but by operating scope. Kbrose (talk) 15:58, 4 February 2009 (UTC)Reply

[[${\displaystyle File:Example.jpg]}$^[1]] —Preceding unsigned comment added by 85.14.31.215 (talk) 11:14, 25 February 2010 (UTC)Reply

Application Layer is working on the TCP. Its works to prepear data to show on human reading form when recving it presentaion Layer and change it on when give presantation Layer. — Preceding unsigned comment added by 180.151.3.178 (talk) 08:16, 2 June 2011 (UTC)Reply

Why are the layers in capital letters? I know Standards Like to Cpaitalize Every Word But That Is Not Wikipedia Style. This certainly sounds like a general concept, since there are so many of them, and even different concepts in the ISO vs. TCP models, for example. W Nowicki (talk) 21:49, 27 September 2011 (UTC)Reply

Did you see the discussion at Talk:OSI_model#Capitalized_layers? — Dgtsyb (talk) 22:09, 27 September 2011 (UTC)Reply

There is a move discussion in progress which affects this page. Please participate at Talk:Physical Layer - Requested move and not in this talk page section. Thank you. —RM bot 03:45, 19 October 2011 (UTC)Reply