IP connectionless and HTTP use TCP

Replies

• 

  silverscorpion

  Well, it's all about layers. There are different layers in a network, and each of the above protocols work in a different layer.
  
  So, HTTP works on the application layer, TCP in the transport layer and IP in the network layer or the internet layer.
  
  Each layer passes data to its adjacent layer. So, HTTP packets are sent to the transport layer, and TCP sends that data to the internet layer.
  
  It can also happen in the reverse order, viz., from internet layer to transport layer to application layer. ie., ip => tcp => http.
  
  In effect, HTTP is a connectionless service, even though TCP is connection-oriented.
  
  It can be confusing at first.. But, try to get the big picture. I hope the answer is clear. Do ask any doubts you might have.
• 

  Munguti

  Each layer in the osi model has a name for its data otherwise called a PDU(Protocal Data Unit). The names for this are
  Physical-Bits
  Data-Frames
  Network-packets or datagrams
  Transport-segment
  all the remaining upper layers have their PDU's refered to as simply data. Hope this clears the problem.
  
  since PDU for layer 3 are also called packets/datagrams so HTTP may use packets or datagrams since that is the same thing but it uses TCP and not UDP for its layer 4 protocol
• 

  Sachin Jain

  silverscorpion

  In effect, HTTP is a connectionless service, even though TCP is connection-oriented.

  I think i should study more about these theoretically and then i will ask.
  Can you please suggest me some website or book name to refer to for clearing this doubt.
• 

  Munguti

  silverscorpion

  In effect, HTTP is a connectionless service, even though TCP is connection-oriented.

  silverscorpion a service is connectionless or connection oriented based on the layer 4 protocol used i.e whether it use UDP or TCP at the transport layer. Since HTTP uses TCP port 80 it is therefore necessarily conection-oriented.
• 

  silverscorpion

  Munguti

  silverscorpion a service is connectionless or connection oriented based on the layer 4 protocol used i.e whether it use UDP or TCP at the transport layer. Since HTTP uses TCP port 80 it is therefore necessarily conection-oriented.

  Well, I didnt know that. But in that case, I have a doubt. HTTP uses TCP alright.. But HTTP doesn't establish dedicated connections between client and server for the whole session, right? For each file to be transferred, new requests are made to the server, right?
  
  So, just because HTTP uses a connection-oriented service, does that make http too connection-oriented?
• 

  Munguti

  silverscorpion

  Well, I didnt know that. But in that case, I have a doubt. HTTP uses TCP alright.. But HTTP doesn't establish dedicated connections between client and server for the whole session, right? For each file to be transferred, new requests are made to the server, right?
  
  So, just because HTTP uses a connection-oriented service, does that make http too connection-oriented?

  But if there is an error in the data received doesnt HTTP request retransmission. If it were connectionless errors would be dropped by the receiver as is the case when streaming live tv or radio and you see glitches in your screen or static in the voice. This means its reliable
  
  And doesnt HTTP use sequences on the packets received, such that though they may travel through various paths they will eventually be put in their correct order and presented to the receiver as they were in the sender
  
  

  silverscorpion

  dedicated connections between client and server for the whole session, right?

  I think dedicated connections would be used in UDP since all packets must arrive in order and as they were sent, again using the example of the live streaming, if packets were to travel different paths wouldnt that mean they might arrive at different times, and who would have the time to arrange them in their correct order without delaying and distorting the live broadcast.