i remembered this please look one second

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i asked about tcp and http

and something came into my mind

http port is 80 ftp port is 20 21

they depend on tcp ?

 

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Yes - those are TCP port numbers.

Harry.

 

but forth layer of the OSI is transport and for delivering
so no need for http or ftp ?


then think on the other side if http is for web pages and ftp is for files for transport why do we need tcp ?


for reliable transferring for flow control for congestion
avoidance ?

 

Considering TCP is a Transport layer (Layer 4) protocol, what do you think handles transport and delivery at that layer of the OSI model? Magic?

THIS is why you need to sit down and study the fundamentals... you wouldn't have these questions if you'd just take our advice and study them.

 

Find a good book on Networking and read it.

The Network Stack, OSI 7 layer model etc, is like an onion or a russian doll. Each layer adds more functionality, or going the other way each layer removes functionality. Its a datapayload that get wrapped by lower level protocols.

The OSI 7 layer model is a theorectical model, depending on the hardware and software design / arch the exact number of layers will be different, however the same basic functions will generally be performed.

http://en.wikipedia.org/wiki/OSI_model

TCP is at the transport layer, there are other transport protocols, you don't have to use TCP, its just everyone pretty much does. It supports the functionality needed to route data across the network.

FTP and HTTP are application level protocols, they support the functionality necessary to transfer files / navigate directories or transfer web pages.

Its a layered or modular design, the higher protocols rely on the services of the lower protocols, HTTP and FTP are simpler because they can rely on the functionlity in TCP/IP.

Unless you are prepared to get learning materials and read them, or spend a long time designing your own network hardware and software from the ground up you won't make progress. I reccomend the first !

 

at that time it can be like this

transport layer will have to know what it moves , if it is a web page , NEEDS for HTTP , if it is a file , NEEDS for FTP


did i understand?

 

i know the things you said man!

 

Dios MIO this is frustrating.

Look Kobem me old mate - BUY A BOOK!!! You will NOT learn anything that you need to know by posting on a forum when you don't have a fundamental grasp of networking.

Why do I feel like Charlie Brown?



Look - it's like this. A client application (like a web browser) communicates with a server application (say, a web server). Now, the client application knows how to 'talk' HTTP, but doesn't know about TCP, IP or any other protocols 'further down' the stack. In order for the HTTP rerquest to be transmitted, it needs to be sent using a medium that can be passed along a wire. This means sending it inside a TCP packet. TCP communication is achieved by ports (hence - HTTP = port 80, FTP = port 21, SMTP = port 25 etc etc etc)

That isn't exactly a scientific explanation of what happens to data in the TCP/IP stack, but it should enable you to see that, without one, the other cannot function.

Now please, please, for the love of holy God buy a book

 

HTTP and FTP are not Transport layer protocols; they are Application layer protocols. TCP is a Transport layer protocol.

Zeb's right... you really, really, REALLY need to study a beginner networking book a bit... otherwise, we're just taking time to type everything you're going to learn there.

 

Well, at least we agree on something, zeb....

 

i didn't mean http and ftp are transport layer protocols

..........

i meant this : transport layer is for transport(delivery)


but transport layer can't know on its own what it (web page or a file) carries

for example (not only tcp can be, also udp but consider tcp)

so if it is a web page , transport layer needs "http" application layer protocol

if its a file , transport layer needs "ftp" application layer protocol to work with

 

The layers don't know or need anything above them.

The knowledge goes downwards only, theres an implied dependancy in most cases, sometimes its concrete like TCP/IP.

For instance TCP knows nothing at all about FTP or HTTP.
HTTP piggybacks on TCP/IP, HTTP knows that TCP/IP exisits, the browser knows about sockets, IP addresses and TCP ports, it does not need to know TCP/IP internals like how reliable transmission is implemented. Its like a layered architecture with API's, you only need know the contract between the layers you depend on.

Each layer merely encapsulates or unwraps the data from the previous layer depending if its transmit or receive.

Some layers are co-dependant like TCP/IP they join to form one protocol. But UDP can also be layered on top of IP. ARP for instance could be a layer but is part of IP in Network layer in OSI model.
See this :- http://en.wikipedia.org/wiki/Address_Resolution_Protocol

It shows TCP/IP stack as a 5 layer model instead of the classic 7 layer model. Some people refer to 'sublayers', the truth is the layers are arbitary, the real implementations are like an ecosystem, the various models are just taxonomies representing them.

 

ROFL - I haven't laughed that hard in ages

and just when you've had enough......

 

Dear gods, its all gibberish to me anyway, but my brain REALLY hurts now.

Kobem, you really, REALLY need to go out and buy one of the (many) TCP/Networking basics books that have been recommended to you (or at least an equivalent in your native language). Your posts to this forum seem to be going in circles. round, and round, and round, and round, ad nauseam. From the viewpoint of someone who also doesnt know this stuff, you seem to be punching above your weight, and getting yourself more and more confused with each answer to your query.

Then you pointedly ignore the (repeated, quality) advice of those who ARE in the know to read up on the subject from basics, either via website or by book (and i mean pointedly. you dont even acknowledge, in any of your threads, that they have supplied you with the resources). To top that all off, When people get annoyed because you arent listening, you switch to a new thread, slightly rephrase the query and repeat (again and again). You then go silent for a few weeks/days, before popping up with a new query that is miles away from the last topic you were 'studying'.

I make no judgement on your continued use of Braindump sites, simply because I see a single obvious BD usage in your post history, and none beyond that. I dont say you are still using them, and I dont say you arent. either way, it makes no odds to what people are telling you here.

This forum is a great resource, and people are MORE than happy to share their hard earned knowledge on a topic with everyone else visiting the site. But its clear that your ignoring the advice given is trying those peoples patience. And, if you continue in this line, you will find less people willing to give you any form of answer to your queries, even so far as an acknowledgement.

Im sure everyone here will agree that they dont WANT to do that, they WANT to help you develop your knowledge and skills, they want to help you develop into a knowledgeable member of this community, who in turn can offer others the same advice given to you. But you HAVE to listen to the advice given to you.

First, forget everything you have 'learned' so far. Get it right out of your head. Then, get a book on the basics of networking. read it (such as the many mentioned already), and ask any questions on those topics you dont get. Pursue a single topic until you fully understand it (both by asking here, and by searching the web, etc), THEN (and only then) move onto the next topic in the book.

And please please please PLEASE stop posting in bold, italics, underline, colours, and caps. Its not necessary. And its downright annoying. Instead, frugally use these punctuation aids to enhance your posts (use bold/italics to highlight an important word/phrase in your post for instance). Use Caps only when required (such as when referring to an abbreviation - eg RAID), or as another aid to emphasise a particular word/phrase. Personally, I have never found a suitable use on this forum for multi-coloured text.

Mods, I've pointedly tried to stay away from this as much as possible and, now that I've made the break, if you feel any of what I've said to be out of line, please let me know and I will happily amend this post.

 

Fergal, your response here seems to be well thought out and courteous.

kobem, you aren't going to get the answers you seem to need by endlessly posting questions about a subject you don't have a basic grasp of. Please stop, re-read all of the advice you've been given, get some quality books on networking and use the links that have been posted in your threads.

Do your homework. Keep reading and studying. There is no such thing as an "instant answer". You're going to have to do the same sort of studying that the rest of us have done to lay the foundation of what you are trying to learn. When you do that, your questions will make more sense to the members of the forum.

 

No... the Transport layer doesn't care what Application layer protocol it's carrying. It doesn't need ANYTHING but TCP. That's why there's a Transport layer, and that's why there's an Application layer. Transport is handled by TCP (or SPX, or any number of other Transport layer protocols), and Application is handled by FTP or HTTP (or any number of other App-layer protocols).

 

It's a valiant effort, but I feel you're fighting a losing battle trying to answer this. When someone refuses to study the basics, the fundamentals, what can you do for them? He'll know the answer to one question if by some miraculous event you get him to understand the answer to this one question, but still fail to grasp anything of importance....

Get yourself some books, Kobem. Go here and you will find every one of your questions answered. If you can't find the answers to your questions at that link you have no intention of studying of studying on your own. It is absolutely, positively, the best internet resource for studying networking that there is.

 

You could also try this web site: -

http://www.learntcpip.com/

It was recomended by another member in a thread I can't seem to find anymore. Anyhows, is a very good start into how tcp/ip and the osi model works.

 

Try looking here...

 

would i need to know this stuff when i do the network infrastructure exam just a question because most of the stuff is foreign to me so i though i better start studying it a bit in my free time.