internetworking with tcp ip 5th edition download

... header contains IP ad- dresses whereas the frame header contains physical addresses Figure 7.2 shows the general form of a datagram: Figure 7.2 General form of an IP datagram, the TCP/IP analogy to ... shipped across the underlying network in a single frame In addition, because IP represents the offset of the data in multiples of eight octets, the fragment size must be chosen to be a multiple ... corrupted data go undetected Fields SOURCE IP ADDRESS and DESTINATION IP ADDRESS contain the 32-bit IP addresses of the datagram's sender and intended recipient Although the datagram may be routed

Ngày tải lên: 04/07/2014, 22:21

... basic unit of transfer in a TCP/IP internet is the IP da- tagram This chapter adds to the description of connectionless service by describing how routers forward IP datagrams and deliver them ... directly to multiple networks Both hosts and routers participate in routing an IP datagram to its destination When an application program on a host attempts to communicate, the TCPJIP protocols ... is to make IP routing decisions What about multi-homed hosts? Any computer with multiple network connections can act as a router, and as we will see, multi-homed hosts running TCPJIP have all

Ngày tải lên: 04/07/2014, 22:21

... always specify the IP address of the original source and the IP address of the ultimate destination? When IP executes the routing algorithm, it selects a new IP address, the IP address of the ... an IP datagram has reached its final destination is not quite as trivial as it seems Remember that even a host may have multiple physical connec- tions, each with its own IP address When an IP ... destination IP address matches the router's own IP address, the IP software passes the datagram to higher-level protocol software for processingt If the datagram has not reached its final destination, IP

Ngày tải lên: 04/07/2014, 22:21

... message mechanism to the TCP/IP protocols The mechanism, known as the Internet Control Message Protocol (ICMP), is considered a required part of IP and must be included in every IP implemen- tation ... ICMP messages are encapsulated and sent using IP, ICMP is not considered a higher level protocol - it is a required part of IP The reason for using IP to deliver ICMP messages is that they may ... Because both the request and reply travel in IP datagrams, successful receipt of a reply verifies that major pieces of the transport system work First, IP software on the source computer must route

Ngày tải lên: 04/07/2014, 22:21

... cycle endlessly As mentioned previously, to prevent datagrams from circling forever in a TCP/IP internet, each IP datagram contains a time-to-live counter, sometimes called a hop count A router decrements ... operate indepen- dently, with each machine maintaining its own notion of the current time Clocks that differ widely can confuse users of distributed systems software The TCPJIP protocol suite includes ... of the IP address scheme We said that the 32-bit addresses are carefully assigned to make the IP addresses of all hosts on a given physical network share a common prefix In the original IP address

Ngày tải lên: 04/07/2014, 22:21

... internet with hundreds of networks and thousands of hosts They did not foresee tens of thousands of small networks of personal computers that would suddenly appear in the decade after TCP/IP was ... them across the WAN toward their des- tination To make demultiplexing efficient, transparent routers often divide the IP address into multiple parts and encode information in unused parts For example, ... that they only work with networks that have a large address space from which to choose host addresses Thus, they work best with class A networks, and they do not work well with class C networks

Ngày tải lên: 04/07/2014, 22:21

... multiple internet addresses map to the same hardware ad- dress The third technique, a TCPnP standard called subnet addressing, allows a site to share a single IP network address among multiple ... they encounter when traversing a TCP/IP internet 11.2 The Need For Multiple Protocols We have said that protocols allow one to specify or understand communication without knowing the details of ... to test along with a number of bits to skip The second, a level compressed trie, provides additional optimization by eliminat- ing one or more levels in the trie that can be skipped along any

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... layer The realistic diagram in Figure 11.2b shows that the IP software may communicate with multiple high-level protocol modules and with multiple network interfaces Although a diagram of conceptual ... 11.5.1 The TCPAP 5-Layer Reference Model The second major layering model did not arise from a standards committee, but came instead from research that led to the TCPIIP protocol suite With a little ... located in the TCP/IP transport layer uses checksums, acknowledgements, and timeouts to con- trol transmission Thus, unlike the connection-oriented X.25 protocol layering, the TCP/IP software focuses

Ngày tải lên: 04/07/2014, 22:21

... while the TCPIIP protocols provide an example of a different layering scheme In practice, protocol software uses multiplexing and demultiplexing to distinguish among multiple protocols within a ... Multiplexing and demultiplexing occur at almost every protocol layer For exam- ple, after the network interface demultiplexes frames and passes those frames that con- tain IP datagrams to the IP ... P (SLIP) and the Point to Point Protocol (PPP) treat each serial link as a separate network The second approach to accommodating point-to-point connections avoids assign- ing multiple IP addresses

Ngày tải lên: 04/07/2014, 22:21

... obtain the destination IP address without interacting with the IP layer However, the source IP ad- dress depends on the route IP chooses for the datagram, because the IP source address identifies ... from IP 12.8 UDP Multiplexing, Demultiplexing, And Ports We have seen in Chapter 11 that software throughout the layers of a protocol hierarchy must multiplex or demultiplex among multiple objects ... UDP cannot know a source IP address unless it interacts with the IP layer We assume that UDP software asks the IP layer to compute the source and (possi- bly) destination IP addresses, uses them

Ngày tải lên: 04/07/2014, 22:21

... here as part of the TCP/IP Internet protocol suite, it is an independent, general purpose protocol that can be adapted for use with other delivery systems For example, because TCP makes very few ... single specification for TCP that can be used to build software for a variety of machines Because TCP assumes little about the underlying communication system, TCP can be used with a variety of packet ... shows the conceptual organiza- tion TCP allows multiple application programs on a given machine to communicate concurrently, and it demultiplexes incoming TCP traffic among application programs

Ngày tải lên: 04/07/2014, 22:21

... times, TCP computes an elapsed time known as a sample round trip time or round trip sample. Whenever it obtains a new round trip sample, TCP adjusts its notion of the average round trip ... why, recall that TCP segments travel encapsulated in IP da- tagrams which are encapsulated in physical network frames. Thus, each segment has at least 40 octets of TCP and IP headers in ... mance. Large segments result in large IP datagrams. When such datagrams travel across a network with small MTU, IP must fragment them. Unlike a TCP segment, a fragment cannot be acknowledged

Ngày tải lên: 04/07/2014, 22:21

... round trip time is slightly longer than some multiple of T Implementations of TCP that associate acknowledgements with the most recent re- transmission have been observed in a stable state with ... estimated round trip time, RTT Unfortunately, lowering the estimated round trip time guarantees that TCP will set the timeout too small for the next segment Ultimately, the estimated round trip time can ... acknowledgement arrives, and TCP retransmits the segment Shortly after TCP retransmits, the first acknowledgement arrives and is associated with the retransmission The round trip sample will be much

Ngày tải lên: 04/07/2014, 22:21

... 13.27 TCP State Machine Like most protocols, the operation of TCP can best be explained with a theoretical model called afinite state machine Figure 13.15 shows the TCP finite state machine, with ... UDP and TCP For example, a domain name server can be accessed either with TCP or with UDP In ei- ther protocol, port number 53 has been reserved for servers in the domain name system 13.30 TCP Performance ... application program instructs TCP to shut down the connection completely, TCP sends the second FIN segment and the original site replies with the third message, an ACK Trang 413.26 TCP Connection Reset

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... of data with each call Thus, the outgoing TCP buffer be- gins with sufficient data for at least one maximum size segment Furthermore, because the application produces data faster than TCP can ... round-trip delays Jain [I9861 describes timer- based congestion control in a sliding window environment Borman [April 19891 sum- marizes experiments with high-speed TCP on Cray computers EXERCISES TCP ... will TCP retransmit significant volumes of data unnecessarily? Lost TCP acknowledgements do not necessarily force retransmissions Explain why Experiment with local machines to determine how TCP

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... longer part of the TCPJIP standards$, it does provide a concrete example of distance-vector routing GGP was designed to travel in IP da- tagrams similar to UDP datagrams or TCP segments Each GGP ... vendors adopted the term IP router, scientists originally used the term IP gateway $The IETF has declared GGP historic, which means that it is no longer recommended for use with TCPAP Trang 7Sec 14.10 ... direct Fire 14.6 An initial distance-vector routing table with an entry for each directly c o ~ e c t e d network Each entry contains the IP address of a network and an integer distance to that

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... Said About The Fourth Edition Of Internetworking With TCPIIP "This is the book I go to for clear explanantions of the basic principles and la- test developments in TCPAP technologies. ... Of The Next IP 602 33.7 Features Of IPv6 602 33.8 General Form Of An IPv6 Datagram 603 33.9 IPv6 Base Header Format 603 33.10 IPv6 Extension Headers 605 33.11 Parsing An IPv6 Datagram ... internetworking in general and the TCP/ IP internet technology in particular. Internetworking is a powerful abstraction that allows us to deal with the complexity of multiple underlying communication...

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