Unformatted text preview: next byte the server is expecting to receive.) Finally,
notice that the retransmission, segment 6, contains data from the missing segment and
segment 4. This is called repacketization, and we'll discuss it more in Section 21.11.
Returning to our discussion of disabling the Nagle algorithm, we can see the 3 bytes of
the next special function key that we type is sent as three individual segments (8, 9, and
10). This time the server echoes the byte in segment 8 first (segment II), and then echoes
the bytes in segments 9 and 10 (segment 12).
What we've seen in this example is that the default use of the Nagle algorithm can cause
additional delays when multibyte keystrokes are entered while running an interactive
application across a WAN. We return to the topic of timeout and retransmission in
Chapter 21. file:///D|/Documents%20and%20Settings/bigini/Docu.../homenet2run/tcpip/tcp-ip-illustrated/tcp_int.htm (11 of 14) [12/09/2001 14.47.18] Chapter 19. TCP Interactive Data Flow Figure 19.8 Time line for Figure 19.7 (Nagle algorithm disabled). 19.5 Window Size Advertisements
In Figure 19.4 we see that slip advertises a window of 4096 bytes and vangogh file:///D|/Documents%20and%20Settings/bigini/Docu.../homenet2run/tcpip/tcp-ip-illustrated/tcp_int.htm (12 of 14) [12/09/2001 14.47.18] Chapter 19. TCP Interactive Data Flow advertises a window of 8192 bytes. Most segments in this figure contain one of these two
Segment 5, however, advertises a window of 4095 bytes. This means there is still 1 byte
in the TCP buffer for the application (the Rlogin client) to read. Similarly, the next
segment from the client advertises a window of 4094 bytes, meaning there are 2 bytes
still to be read.
The server normally advertises a window of 8192 bytes, because the server's TCP has
nothing to send until the Rlogin server reads the received data and echoes it. The data
from the server is sent after the Rlogin server has read its input from the client.
The client TCP, on the other hand, often has data to send when the ACK ar...
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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