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Unformatted text preview: rives, since it's
buffering the received characters just waiting for the ACK. When the client TCP sends
the buffered data, the Rlogin client has not had a chance to read the data received from
the server, so the client's advertised window is less than 4096. 19.6 Summary
Interactive data is normally transmitted in segments smaller than the maximum segment
size. With Rlogin a single byte of data is normally sent from the client to the server.
Telnet allows for the input to be sent one line at a time, but most implementations today
still send single characters of input.
Delayed acknowledgments are used by the receiver of these small segments to see if the
acknowledgment can be piggybacked along with data going back to the sender. This
often reduces the number of segments, especially for an Rlogin session, where the server
is echoing the characters typed at the client.
On slower WANs the Nagle algorithm is often used to reduce the number of these small
segments. This algorithm limits the sender to a single small packet of unacknowledged
data at any time. But there are times when the Nagle algorithm needs to be disabled, and
we showed an example of this.
19.1 Consider a TCP client application that writes a small application header (8 bytes)
followed by a small request (12 bytes). It then waits for a reply from the server. What
happens if the request is sent using two writes (8 bytes, then 12 bytes) versus a single
write of 20 bytes?
19.2 In Figure 19.4 we are running tcpdump on the router sun. This means the data in
the arrows from the right to the left still have to go through bsdi, and the data in the file:///D|/Documents%20and%20Settings/bigini/Docu.../homenet2run/tcpip/tcp-ip-illustrated/tcp_int.htm (13 of 14) [12/09/2001 14.47.18] Chapter 19. TCP Interactive Data Flow arrows from the left to the right have already come through bsdi. When we see a
segment going to slip, followed by a segment coming from slip, the time differences
between the two are: 34.8, 26.7, 30.1,...
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.
- Spring '12