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Animation 15_1 |
A host uses ARP to determine the hardware address of the destination
of an IP datagram. The sender broadcasts an ARP request, the
destination responds with an ARP reply and the sender sends the IP
datagram directly to the destination.
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Animation 16_1 |
Hosts and routers consult routing tables to forward IP datagrams.
Each host or router looks in its routing table to determine the next
hop to the destination. If the routing tables are changed, IP
datagrams will follow different paths to the destination.
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Animation 16_2 |
This animation converts between 32-bit hexadecimal numbers and the
fields in an IP datagram header.
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Animation 17_1 |
In an internet, the protocol software on the source computer constructs
an IP datagram and transmits it to a router
by encapsulating the datagram in a hardware frame. The router
extracts the datagram and retransmits it in a new hardware frame
to the next router on the path to the destination; the destination
extracts the original datagram from the last hardware frame and
delivers the data to the application.
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Animation 20_1 |
TCP specifies a three-way handshake to establish a TCP connection
between two computers; the initiating computer send a segment
with the SYN bit sent; the receiving computer responds with a
segment with the SYN and ACK bits sent; the initiating computer
then completes the handshake with a segment with the ACK bit set.
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Animation 20_2 |
TCP specifies a three-way handshake to terminate a TCP connection;
the computer initiating the termination sends a segment with
the FIN bit sent, the computer at the other end of the connection
responds with a segment with the FIN and ACK bits set; the initiating
computer then completes the termination handshake with a segment
with the ACK bit set.
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Animation 20_3 |
TCP uses sliding window flow control. The receiver defines the
window, and the sender can transmit any of the data in the window.
When the sender receives an acknowledgment, the window moves ahead to
include new, unsent data.
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Animation 20_4 |
By changing the size of the window, the receiver can control the rate
at which data are sent.
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Animation 20_5 |
If a segment is lost, the window does not advance until the segment is
retransmitted and the sender receives the acknowledgment for the segment.
When the receiver gets a segment out of order, it can send an
acknowledgment for the highest received data byte without sending
individual acknowledgments for the intermediate data.
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Figure 16.3 |
Examples of older protocol stacks that have been replaced by
TCP/IP protocols. Although the stacks shared many general concepts, the
details differed, making them incompatible.
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Figure 17.3 |
The internet concept. (a) The illusion of a single network that TCP/IP
software provides to users and applications, and (b) the underlying physical
structure in which a computer attaches to one physical network, and routers
interconnect the networks.
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Figure 17.4 |
The five layers of the TCP/IP reference model.
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Figure 18.1 |
The five classes of IP addresses in the original classful scheme. The
address assigned to a host is either class A, B, or C;
the prefix identifies a network, and the suffix is unique to a
host on that network.
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Figure 18.2 |
The mapping between the first four bits of an IP address and the
class of the address. The mapping was used with the original classful
scheme.
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Figure 18.3 |
Examples of 32-bit binary numbers and their equivalent in
dotted decimal notation. Each octet is written in decimal with
periods (dots) used to separate octets.
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Figure 18.4 |
The range of decimal values found in the first octet of each
address class.
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Figure 18.5 |
The number of networks and hosts per network in each of the three
primary IP address classes.
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Figure 18.6 |
An example private internet with IP addresses assigned to hosts. The
size of the cloud used to denote a physical network corresponds to the
number of hosts expected on the network; the size of a network determines
the class of address assigned.
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Figure 18.7 |
Illustration of CIDR addressing for a /28 prefix. Note that because
bits are numbered starting at zero, the prefix covers bits 0 through 27. Thus,
bits 28 through 31 correspond to the host suffix.
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Figure 18.8 |
Summary of the special IP address forms.
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Figure 19.1 |
A simple internet with routers R1 and R2 connecting
three physical networks; each network has two host computers attached.
A computer can only resolve the address of a computer attached to
the same physical network.
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Figure 19.2 |
An example address binding table. Each entry in the table contains a
protocol address and the equivalent hardware address.
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Figure 19.3 |
An example of direct lookup for a class C network. The host
portion of an address is used as an array index.
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Figure 19.4 |
Comparison of address resolution using a table lookup (T),
closed-form computation (C), and dynamic message exchange (D).
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Figure 19.5 |
An ARP message exchange. (a) Computer W begins to broadcast an
ARP request that contains computer Y's IP address. (b) All computers
receive the request, and (c) computer Y sends a response directly to
W.
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Figure 19.8 |
Illustration of the type field in an Ethernet header used to
specify the frame contents. A value of 0x806 informs the receiver
that the frame contains an ARP message.
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Figure 20.1 |
The general form of an IP datagram with a header followed by data. The
header contains information that controls where and how the datagram is to
be sent.
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Figure 20.2 |
(a) An example internet with three routers connecting four physical
networks, and (b) the conceptual routing table found in
router R2. Each entry in the table lists a destination
network and the next hop along a route to that network.
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Figure 20.3 |
(a) An internet of four networks and three routers with an IP address
assigned to each router interface, and (b) the routing table found in
the center router. Each entry in the table lists a destination,
a mask, and the next hop used to reach the destination.
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Figure 20.4 |
Fields in the IP datagram header. Both the source and destination
addresses are Internet addresses.
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Figure 21.1 |
An IP datagram encapsulated in a hardware frame. The entire datagram
resides in the frame data area. In practice, the frame format used with
some technologies includes a frame trailer as well as a frame header.
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Figure 21.2 |
An IP datagram as it appears at each step during a trip across an
internet. Whenever it travels across a physical network, the datagram
is encapsulated in a frame appropriate to the network.
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Figure 21.4 |
An IP datagram divided into three fragments. Each fragment carries
some data from the original datagram, and has an IP header similar to the
original datagram.
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Figure 21.5 |
An example internet in which hosts can generate datagrams that require
fragmentation. Once a datagram has been fragmented, the fragments are
forwarded to the final destination, which reassembles them.
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Figure 22.1 |
The general form of an IPv6 datagram. Extension headers are
optional -- the minimum datagram has a base header followed by data.
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Figure 22.2 |
The format of an IPv6 base header. The header contains fewer fields
than the IPv4 datagram header.
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Figure 22.3 |
Two IPv6 datagrams in which (a) contains a base header plus data, and
(b) contains a base header, route header, and data. The NEXT HEADER
field in each header specifies the type of the item that follows.
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Figure 22.4 |
The IPv6 options extension header. Because the size of the options
header can vary from one datagram to another, the HEADER LEN
field specifies the exact length.
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Figure 22.5 |
Illustration of fragmentation in IPv6. The fragmentable part of the
original datagram (a), is placed in the payload area of fragments
(b, c, and d). Each fragment begins with a copy of the
unfragmentable part and a fragment extension header.
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Figure 24.1 |
The format of a UDP user datagram. Each user datagram begins
with an eight octet header followed by the data being sent.
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Figure 24.2 |
The encapsulation of a UDP message in an IP datagram. The entire
UDP message, including the header and data areas resides in the data
area of the IP datagram.
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Figure 25.1 |
An example internet that illustrates why TCP is an end-to-end
transport protocol. TCP views IP as a mechanism that allows TCP software
on a host to exchange messages with TCP software on a remote host.
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Figure 25.2 |
Example of retransmission. Items on the left correspond to events in
a computer sending data, items on the right correspond to events in a
computer receiving data, and time goes down the figure. The sender
retransmits lost data.
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Figure 25.3 |
Timeout and retransmission on two connections that have different
round-trip delays. TCP optimizes throughput by using a round-trip estimate
to compute a retransmission timer.
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Figure 25.4 |
A sequence of messages that illustrates TCP flow control when the
maximum segment size is 1000 octets. A sender can transmit enough
data to fill the currently advertised window.
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Figure 25.5 |
The 3-way handshake used to close a connection. Acknowledgements
sent in each direction are used to guarantee that all data has arrived
before the connection is terminated.
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Figure 25.6 |
The TCP segment format. Each message sent from TCP on one machine to
TCP on another (both data and acknowledgements) uses this format.
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Figure 26.1 |
Illustration of how NAT is used. A device running NAT is placed
on the connection between a site and the Internet.
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Figure 26.2 |
Illustration of basic NAT translation. NAT rewrites the source
address in outgoing datagrams and the destination address in incoming
datagrams.
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Figure 26.3 |
An example NAT translation table for the mapping illustrated
in Figure 26.2. An entry specifies the direction of packet flow
and the changes that should occur.
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Figure 26.4 |
An example NAPT translation table for TCP connections from
private computers 10.0.0.1 and 10.0.0.2. NAPT changes both the IP
source address and TCP port number. In the example, both connections
use TCP source port 30000 (unlikely, but possible).
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Figure 26.5 |
Illustration of a dedicated NAT device that provides connections
for multiple computers. The NAT box connects to an ISP (e.g., through
a DSL connection or a cable modem).
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Figure 28.1 |
A client and server using TCP/IP protocols to communicate across an
internet. The client and server each interact with a protocol in the
transport layer.
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Figure 28.2 |
Two servers on a single computer accessed by clients on two other
computers. Client 1 can access server 1, while client 2
accesses server 2.
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Figure 31.2 |
A graphical representation that illustrates one way a DNS hierarchy
might be structured in a corporation. Names for individual computers can
be added to the diagram as well.
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Figure 40.1 |
Illustration of a firewall that is used to protect an organization
against unwanted interaction with the Internet.
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Figure 41.1 |
The first few steps that TCP/IP protocol software takes to
obtain configuration information. T1 and T2 denote
timeout values.
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Figure 41.2 |
The format that BOOTP uses for request and response messages. The
message is sent using UDP, which is encapsulated in IP.
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Figure 41.3 |
The DHCP message format, a slightly modified version of
the BOOTP format.
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Photo img3_039 |
An in-use Cisco 7000 router with a varity of interfaces. The router
has six AUI Ethernet ports in its leftmost slot to which the six grey
cables connect. It also has four serial ports, to which three grey
serial lines connect. Further right is a single fiber optic ATM
interface identified by the orange cable. To the right of that is a
FDDI interface to which the two light grey fiber optic cables are
connected.
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Photo img3_040 |
An in-use Cisco 7000 router with a varity of interfaces. The router
has six AUI Ethernet ports in its leftmost slot to which the six grey
cables connect. It also has four serial ports, to which three grey
serial lines connect. Further right is a single fiber optic ATM
interface identified by the orange cable. To the right of that is a
FDDI interface to which the two light grey fiber optic cables are
connected.
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Photo img3_041 |
An in-use Cisco 7000 router with a varity of interfaces. The router
has six AUI Ethernet ports in its leftmost slot to which the six grey
cables connect. It also has four serial ports, to which three grey
serial lines connect. Further right is a single fiber optic ATM
interface identified by the orange cable. To the right of that is a
FDDI interface to which the two light grey fiber optic cables are
connected.
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Photo img3_042 |
An in-use Cisco 7000 router with a varity of interfaces. The router
has six AUI Ethernet ports in its leftmost slot to which the six grey
cables connect. It also has four serial ports, to which three grey
serial lines connect. Further right is a single fiber optic ATM
interface identified by the orange cable. To the right of that is a
FDDI interface to which the two light grey fiber optic cables are
connected.
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Photo img3_063 |
The larger device at the bottom is a Cisco 7000 router. On top is a
Fore ForeRunner ASX-200 ATM switch with various twisted pair and
fiber optic connections.
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Photo img3_064 |
The larger device at the bottom is a Cisco 7000 router. On top is a
Fore ForeRunner ASX-200 ATM switch with various twisted pair and
fiber optic connections.
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Photo img4_017 |
A Cisco 7500 router. The top slot is occupied by the routers'
processor board. Third slot from the top on the left is a fiber optic
ATM interface which is concealed by a dust cover. The slot below
contains 6 Ethernet AUI connectors.
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Photo img4_018 |
A Cisco 7500 router. The top slot is occupied by the routers'
processor board. Third slot from the top on the left is a fiber optic
ATM interface which is concealed by a dust cover. The slot below
contains 6 Ethernet AUI connectors.
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Photo img4_019 |
A Cisco 7500 router. The top slot is occupied by the routers'
processor board. Third slot from the top on the left is a fiber optic
ATM interface which is concealed by a dust cover. The slot below
contains 6 Ethernet AUI connectors.
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Photo img4_020 |
A Cisco 7500 router. The top slot is occupied by the routers'
processor board. Third slot from the top on the left is a fiber optic
ATM interface which is concealed by a dust cover. The slot below
contains 6 Ethernet AUI connectors.
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Photo img4_021 |
A Cisco 7500 router. The top slot is occupied by the routers'
processor board. Third slot from the top on the left is a fiber optic
ATM interface which is concealed by a dust cover. The slot below
contains 6 Ethernet AUI connectors.
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Photo img4_022 |
A Cisco 7500 router. The top slot is occupied by the routers'
processor board. Third slot from the top on the left is a fiber optic
ATM interface which is concealed by a dust cover. The slot below
contains 6 Ethernet AUI connectors.
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Photo img4_023 |
A Cisco 2514 Router. On the left are two Ethernet AUI connectors.
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Photo img4_024 |
A Cisco 2514 Router. On the left are two Ethernet AUI connectors.
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Photo img4_025 |
A Cisco 2514 Router. On the left are two Ethernet AUI connectors.
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Photo img4_026 |
A Cisco 2514 Router. On the left are two Ethernet AUI connectors.
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Photo img4_027 |
A Cisco 2514 Router. On the left are two Ethernet AUI connectors.
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Photo img4_028 |
A Cisco 2514 Router. On the left are two Ethernet AUI connectors.
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Photo img4_029 |
A Cisco 2514 Router. On the left are two Ethernet AUI connectors.
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Data file 1 |
Trace of all IP traffic on Ethernet
segment. Contains approximately 87,000 packets and 6.5Mb. Trace
includes packet headers only.
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Data file 2 |
Anonymous FTP session with dir, get
and put. Contains approximately 930Kbytes and 2300
packets.
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Data file 3 |
Anonymous FTP session using mput in
both ascii and binary modes. Contains approximately
33Kbytes and 340 packets.
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Data file 4 |
Anonymous FTP session using mget in both
ascii and binary modes. Contains approximately
37Kbytes and 370 packets.
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Data file 5 |
TELNET session (headers only). Contains approximately
45Kbytes and 560 packets.
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Data file 6 |
SMTP session with delivery of one mail message from
SMTP client to SMTP server. Contains approximately 3,000 bytes and 30
packets.
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Data file 7 |
WWW browser session accessing multiple URLs from
multiple WWW servers. Contains approximately 590Kbytes and 1,270
packets.
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Data file 8 |
X Window System application protocol messages from
several clients, including xterm, emacs,
xspread and xpaint to an X server. Contains
approximately 760Kbytes and 5,500 packets.
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