Question

a webpage refer to javascript file for interconnectivty and two css file for styling. how many RTTs are required for browser to fully display the page using non persistent and persistent http?

Answer 1

RTT(Round-Trip TIme) is the time required to send a message and get its reply from the server.

In Non-Persistent HTTP, the client sends a TCP connection request to the server and server after recieving the request sends an acknowledgement to the client. It takes one RTT. After that client sends a http request message for object and server after getting it sends the object ( which also takes one RTT) and then after client acknowledges that it has recieved the object,then TCP close the connection.

In case of Persistent HTTP, the server doesn't close the TCP connection. Thus more than one object can be requested via the same TCP connection.

For NON-PERSISTENT HTTP = 3 * (1 RTT for TCP connection request + 1 for file transfer)

ANS = 6 RTT.

For PERSISTENT HTTP

(without pipelining)

1 RTT for TCP connection request + 3*(1 for file transfer)

ANS = 4 RTT.

(with pipelining)

In pipelining, simulatenous requests can be made without waiting for pending requests.

1 RTT for TCP connection request + 1*(1 for file transfer)

ANS = 2 RTT.

Persistent HTTP with pipelining is the default operation mode of HTTP

Note:

We are assuming no packets are lost in transmission.

And all objects are on the same server.

And since webpage refers the Javascript file and two css. It is also assumed that the initial webpage has been recieved.