internetworking with tcpip ebook download

... guidelines as the original definition: datagrams with a higher number in their pre- cedence field are given preferential treatment over datagrams with a lower number That is, the eight ordered ... datagrams will be delivered without fragmentation The source can choose any datagram size it thinks appropriate; fragmentation and reassembly occur automatically, without the source taking special ... the datagram, the destination must obtain all fragments start- ing with the fragment that has offset 0 through the fragment with highest offset Frag- ments do not necessarily arrive in order,

Ngày tải lên: 04/07/2014, 22:21

... octets The fields starting with the one labeled FIRST IP ADDRESS comprise the area reserved for recording internet addresses The POINTER field specifies the offset within the option of the next ... routers record their IP addresses along with timestamps because the record route option already provides that capability However, recording IP addresses with timestamps eliminates Universal Time ... IP routing informa- tion Like routing within a single physical network, IP routing chooses a path over which a datagram should be sent Unlike routing within a single network, the IP rout- ing

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... network To visualize how indirect routing works, imagine a large internet with many net- works interconnected by routers but with only two hosts at the far ends When one host wants to send to the ... traffic follow the same path without regard to the delay or throughput of physical networks Second, because only the final router along the path attempts to communicate with the destination host, ... based on the contents of routing tables, without saying how systems initialize their routing tables or update them as the network changes Later chapters deal with these questions and discuss protocols

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... far, each router operates auto- nomously, routing or delivering datagrams that arrive without coordinating with the ori- ginal sender The system works well if all machines operate correctly and ... The important difference between having a single network implemented with dedicated hardware and an internet implemented with software is that in the former, the designer can add special hardware ... unknown Destination host unknown Source host isolated Communication with destination network administratively prohibited Communication with destination host administratively prohibited Network unreachable

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... exactly 24 packets Compare ICMP source quench packets with Jain's 1-bit scheme used in DECNET Which is a more effective strategy for dealing with congestion? Why? There is no ICMP message that ... local network Also try to communi- cate with a nonexistent host on a remote network In which case do you receive an error message? Why? 9.15 Try using ping with a network broadcast address How ... (14); the IDEN- TIFIER and SEQUENCE NUMBER fields are used by the source to associate replies with requests Remaining fields specify times, given in milliseconds since midnight, Universal Time?

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... A, B, C, or D) With subnets, it is not possible to decide which bits correspond to the network and which to the host from the address alone Instead, the modified algo- rithm used with subnets ... stead, the example demonstrates a technique often employed with unnumbered net- works Rather than leaving the next hop empty, it is filled with one of the IP addresses assigned to the next-hop router ... 2 (subnet of address N) Net 3 (subnet of address N) Figure 10.7 An example (illegal) topology with three networks where Nets 2 and 3 are subnets of a single IP network address, N If such to-

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... propagated correctly Can transparent routers be used with local area networks like the Ethernet? Why or why not? Show that proxy ARP can be used with three physical networks that are interconnected ... be extracted and used as a key If multiple routes hash to the same bucket in the table, entries within the bucket are arranged in de- creasing order of specificity - subnet routes precede network ... successive bits in the address determine a path from the root downward A binary trie is a tree with paths determined by the data stored To visualize a binary trie, imagine that a set of 32-bit

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... From the analogy with pro- gramming languages, we can see how to conquer the complexity Program translation has been partitioned into four conceptual subproblems identified with the software ... 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 protocol ... (PAD) on the network with dialup access Subscribers, often travelers who cany their own computer and modem, dial up the local PAD, make a network connection to the host with which they wish to

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... destinations from the functions they implement without knowing the process that implements the function (e.g., to allow a sender to contact a file server without knowing which process on the destination ... extracts them To communicate with a foreign port, a sender needs to know both the IF' address of the destination machine and the protocol port number of the destination within that machine Each message ... destinations within one host FRAME DATA AREA Thus, only the IP header identifies the source and destination hosts; only the UDP layer identifies the source or destination ports within a host

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... data that has been generated without waiting to fill a buffer When it reaches the receiving side, the push causes TCP to make the data available to the application without delay The reader should ... single fundamental technique known as positive acknowledgement with retransmission The technique requires a recipient to communi- cate with the source, sending back an acknowledgement (ACK) message ... call Before transfer can start, both the sending and receiving application pro- grams interact with their respective operating systems, informing them of the desire for a stream transfer Conceptually,

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... 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 circles representing states and arrows ... accessible from both 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 ... transmitting the remaining data, waits for the receiver to acknowledge it, and then sends a segment with the FIN bit set The receiving TCP acknowledges the FIN segment and informs the application

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... central authority, other routers could not interfere with the exchange The original core system was arranged to permit new core routers to be added without modifying existing routers When a new router ... not always produce desirable results For example, a path with hop count 3 that crosses three LANs may be substantially faster than a path with hop count 2 that crosses two slow speed serial lines ... longer recommended for use with TCPAP Trang 7Sec 14.10 Distance Factoring 265 14.10 Distance Factoring Like most routing protocols, GGP uses multiple message types, each with its own format and

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... core routers formed an autonomous system Each change in routing protocols within the core autonomous system was made without affecting the routers in other autonomous systems In the previous ... architecture, depicted by Figure 15.2, with auto- nomous systems replacing local area networks Figure 15.3 illustrates the idea System 1 Figure 153 Architecture of an internet with autonomous systems at ... autonomous system to comrnuni- cate with another Coordination Among Multiple BGP Speakers If an autonomous system has multi- ple routers each communicating with a peer in an outside autonomous

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... omitted from the message Field WITHDRAWN LEN is a 2-octet field that specifies the size of the Withdrawn Destinations field that follows If no destinations are being with- drawn, WlTHDRAWN LEN ... header, with the first octet specifying the type of the parameter, and the second octet specifying the length If there are no parameters, the value of PARM LEN is zero and the message ends with ... Path Attributes that are associated with new destinations being advertised If there are no new destinations, the PATH LEN field contains zero Trang 30 16 31 WITHDRAWN LEN 1 PATH LEN I Path

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... evolve, centralized roots are evident in many protocols Without some centralization, each ISP would need to exchange reachability information with all ISPs to which it attached Consequently, the ... networks within its system to other autonomous systems This chapter completes our overview of internet routing by examining how a router in an autonomous system learns about other net- works within ... In the figure, IGP, refers to the interior router protocol used within autonomous system 1, and IGP, refers to the protocol used within autonomous system 2 The figure also illustrates an important

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... Sun Microsystems internal use Update Request (used with demand circuits) Update Response (used with demand circuits) Update Acknowledge (used with demand circuits) A router or host can ask another ... 1 through 16, with distance 16 used to signify infinity (i.e., no route exists) 16.3.6 RIP1 Route Interpretation And Aggregation Because RIP was originally designed to be used with classful ... is part of the subnetted p r e f ~ , and only if the subnet mask used with the net- work is the same as the subnet mask used with the address In essence, the restriction means that RIPl cannot

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