- Data tranfer with TCP:
- Data transfer
in TCP uses:
- the sliding window protocol where each byte is assigned a sequence number
- Data transfer
in TCP uses:
- Example data transfer
in TCP ---
"Simple" transfer (server has
no data to send back to client)
- Client and
server
must have consistent
send/ACK numbers:
- Suppose the
client
sends a 10 bytes
to the server:
- The server will
accepts the
message and
update the
ACK no:
The server will return an ACK message for the 10 bytes:
- When client will
receive the
ACK message, the
client updates
its send seq no
(to 110):
- Client and
server
must have consistent
send/ACK numbers:
- Note:
- The server's ACK message need
not to be
acknowledged
Remember that:
- Do not
acknowledge an
ACK message
- Otherwise, you have an infinite loop of ACK messages
- Do not
acknowledge an
ACK message
- The server's ACK message need
not to be
acknowledged
- Example data transfer in
TCP ----
Bi-directional data transfer
with piggyback ACK
- The client
sends 10 bytes
to the server:
- The server
sends back a 30 byte message reply
to the client:
Notice that:
- The ACK message for the client's 10 bytes is piggy-backed in the data message !!!
- When the clients
receive the 30 bytes from
the server,
the client sends back
an ACK:
- When the server receives
the ACK message from the
client, it
updates its
send seq no:
NOTE:
- This TCP segment (= ACK message)
contains
no data, so:
- The server must not send any ACK for this message !
- This TCP segment (= ACK message)
contains
no data, so:
- The client
sends 10 bytes
to the server: