Review #2--A protocol for packet network intercommunication by Cerf V. G. and Kahn, R. E.

From: Rosalia F Tungaraza (rltungar@cs.washington.edu)
Date: Wed Oct 06 2004 - 00:42:57 PDT

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    The authors describe the design and philosophy of the TCP
    protocol, which unlike other protocols at the time enabled different
    networks to send packets of data (of any size) between them.
    In general, this protocol relies on gateways to
    relay those packets from one network to the other. Each gateway on the
    other hand, has the ability to re-size any packet so as to fit the
    requirements of the succeeding network.
     
    On the process level, the TCP protocol dictates the flow of packets
    through multiplexing them to internetwork processes (via gateways) and
    demultiplexing them to processes in the network. For example, when
    demultiplexing, the protocol reassembles all the packets that were sent as
    one message to a given process. Then decodes the process header section of
    that packet, determines which process was addressed and delivers the
    packet to it.

    Additional features of this protocol include its ability to retransmit a
    packet if the initial wasn't delivered (i.e. it didn't receive an
    acknowledgment for it), and drop a packet(s) if it was received in the
    wrong order.

    The authors succeeded in breaking down the components of the TCP protocol
    in such a way that a third party seeking to implement it (in their own
    flavor) would easily identify the needed functionality. In other words, it
    is general enough that it doesn't restrict anybody to one particular
    implementation.

    One limitation to the TCP protocol is that it has the potential to be
    speed constraining. By this I mean, if a process needs packets to be sent
    to it in specific time interval across various networks, the design of
    this protocol may cause a delay (mainly due to the time needed to re-size
    packets when passing through various gateways, decode the different
    headers, e.t.c.). Eventually, this could also minimize a network's overall
    performance. A possible solution would be to supplement this protocol with
    other protocols such as UDP (a strategy employed by contemporary
    networks).

    For future work, this paper provides a blueprint of the TCP protocol upon
    which various implementations could be created and tested to examine how
    good they are in terms of their performances, reliability, and
    user-ability. Since to this date there are many implementations of this
    protocol, it would be an interesting study to see how variations in the
    implementations affect user-ability. In other words, how different ISPs
    optimized this protocol to make ends meet.


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