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Unformatted text preview: the implementation of this TCP option that are covered in
the references. We summarize them here:
q q q q q q The server's SYN, ACK (the second segment) should be delayed, to allow the
reply to piggyback with it. (Normally the ACK of a SYN is not delayed.) It can't
delay too long, or the client will time out and retransmit.
The request can require multiple segments, but the server must handle their
possible out-of-order arrival. (Normally when data arrives before the SYN, the
data is discarded and a reset is generated. With T/TCP this out-of-order data
should be queued instead.)
The API must allow the server process to send data and close the connection in a
single operation to allow the FIN in the second segment to piggyback with the
reply (Normally the application would write the reply, causing a data segment to
be sent, and then close the connection, causing the FIN to be sent.)
The client is sending data in the first segment before receiving an MSS
announcement from the server. To avoid restricting the client to an MSS of 536,
the MSS for a given host should be cached along with its CC value.
The client is also sending data to the server without receiving a window
advertisement from the server. T/TCP suggests a default window of 4096 bytes
and also caching the congestion threshold for the server.
With the minimal three-segment exchange there is only one RTT that can be
measured in each direction. Plus the client's measured RTT includes the server's
processing time. This means the smoothed RTT value and its variance also must
be cached for the server, similar to what we described in Section 21.9. The appealing feature of T/TCP is that it is a minimal set of changes to an existing
protocol but allows backward compatibility with existing implementations. It also takes file:///D|/Documents%20and%20Settings/bigini/Docu.../homenet2run/tcpip/tcp-ip-illustrated/tcp_fut.htm (18 of 20) [12/09/2001 14.47.34] Chapter 24. TCP Futures and Performance advantage of existing engineering features of TCP (dynamic timeout and retransmission,
congestion avoidance, etc.) instead of forcing the application to deal with...
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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