Chapter 2
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2.1
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Visit http://www.iana.org/numbers.htm
and find the registry called "IP Version Number." Version 0 is
reserved, versions 1鈥? are unassigned, and version 5 is the
Internet Stream Protocol.
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2.2
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All RFCs are available at no charge through
electronic mail, anonymous FTP, or the Web. A starting point is
http://www.ietf.org. The
directory ftp://ftp.rfc-editor.org/in-notes
is one location for RFCs. To start, fetch the current RFC index,
normally the file rfc-index.txt, also available in an HTML
version at http://www.rfc-editor.org/rfc-index.html.
If we search the RFC index (see the solution to the previous
exercise) with an editor of some form, looking for the term
"Stream," we find that RFC 1819 defines Version 2 of the Internet
Stream Protocol. Whenever looking for information that might be
covered by an RFC, the RFC index should be searched.
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2.3
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With IPv4, this generates a 576-byte IP datagram
(20 bytes for the IPv4 header and 20 bytes for the TCP header), the
minimum reassembly buffer size with IPv4.
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2.4
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In this example, the server performs the active
close, not the client.
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2.5
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The host on the token ring cannot send packets
with more than 1,460 bytes of data because the MSS it received was
1,460. The host on the Ethernet can send packets with up to 4,096
bytes of data, but it will not exceed the MTU of the outgoing
interface (the Ethernet) to avoid fragmentation. TCP cannot exceed
the MSS announced by the other end, but it can always send less
than this amount.
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2.6
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The "Protocol Numbers" section of the Assigned
Numbers Web page (http://www.iana.org/numbers.htm)
shows a value of 89 for OSPF.
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2.7
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A selective acknowledgment only indicates that
the data covered by the sequence numbers reflected in the selective
acknowledgment message was received. Only a cumulative
acknowledgment says that the data up to and including the sequence
number in the cumulative acknowledgment message was received. When
freeing data from the send buffer based on a selective
acknowledgment, the system may only free the exact data that was
acknowledged, and not any before or after the selective
acknowledgment.
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