rfc1195.ps

<VC++网络游戏建摸与实现>源代码

81.4 0 32 (derlying link layer services without the need for mutual encapsulation. The integrated IS\255IS is a) W
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(dynamic routing protocol, based on the SPF \(Dijkstra\) routing algorithm. ) h
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50.2 0 32 (The protocol described in this specification allows for mixing of IP\255only, OSI\255only, and dual \(IP) W
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(and OSI\) routers, as defined below. ) h
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13.5 0 32 (An IP\255only IS\255IS router \(or ) W
13.5 0 32 (\026) W
13.5 0 32 (IP\255only) W
13.5 0 32 (\027) W
13.5 0 32 ( router\) is defined to be a router which: \(i\) Uses IS\255IS as the) W
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29.4 0 32 (routing protocol for IP, as specified in this report; and \(ii\) Does not otherwise support OSI proto\255) W
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(cols. For example, such routers would not be able to forward OSI CLNP packets.) h
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48.4 0 32 (An OSI\255only router is defined to be a router which uses IS\255IS as the routing protocol for OSI, as) W
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81.5 0 32 (specified in [1]. Generally, OSI\255only routers may be expected to conform to OSI standards, and) W
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(may be implemented independent of this specification.) h
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63.7 0 32 (A dual IS\255IS router \(or ) W
63.7 0 32 (\026) W
63.7 0 32 (dual) W
63.7 0 32 (\027) W
63.7 0 32 ( router\) is defined to be a router which uses IS\255IS as a single inte\255) W
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(grated routing protocol for both IP and OSI, as specified in this report.) h
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54.8 0 32 (This approach does not change the way that IP packets are handled. IP\255only and dual routers are) W
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85.3 0 32 (required to conform to the requirements of Internet Gateways [4]. The integrated IS\255IS protocol) W
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113.2 0 32 (described in this report outlines an Interior Gateway Protocol \(IGP\) which will provide routing) W
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75.1 0 32 (within a TCP/IP routing domain \(i.e., autonomous system\). Other aspects of router functionality) W
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(\(e.g., operation of ICMP, ARP, EGP, etc.\) are not affected by this proposal.) h
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52.5 0 32 (Similarly, this approach does not change the way that OSI packets are handled. There will be no) W
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26.3 0 32 (change at all to the contents nor to the handling of ISO 8473 Data packets and Error Reports, nor) W
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129.2 0 32 (to ISO 9542 Redirects and ES Hellos.  ISO 9542 IS Hellos transmitted on LANs are similarly) W
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64.4 0 32 (unchanged. ISO 9542 IS Hellos transmitted on point\255to\255point links are unchanged except for the) W
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157.8 0 32 (addition of IP\255related information. Similarly, other OSI packets \(specifically those involved in) W
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97.8 0 32 (the IS\255IS intra\255domain routing protocol\) remain unchanged except for the addition of IP\255related) W
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(information. ) h
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0.5 0 32 (This approach makes use of the existing IS\255IS packets, with IP\255specific fields added. Specifically:) W
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88.4 0 32 (\(i\) authentication information may be added to all IS\255IS packets; \(ii\) the protocols supported by) W
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18.2 0 32 (each router, as well as each router's IP addresses, are specified in ISO 9542 IS Hello, IS\255IS Hello) W
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9.3 0 32 (and Link State Packets; \(iii\) internally reachable IP addresses are specified in all Link State Pack\255) W
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31.4 0 32 (ets; and \(iv\) externally reachable IP addresses, and external routing protocol information, may be) W
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57.5 0 32 (specified in level 2 Link State Packets. The detailed encoding and interpretation of this informa\255) W
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(tion is specified in sections 3, 4, and 5 of this RFC.) h
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127.3 0 32 (The protocol described in this report may be used to provide routing in an IP\255only routing do\255) W
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2.1 0 32 (main, in which all routers are IP\255only. Similarly, this protocol may be used to provide routing in a) W
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154.3 0 32 (pure dual domain, in which all routers are dual. Finally, this protocol may be used to provide) W
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118.1 0 32 (routing in a mixed domain, in which some routers are IP\255only, some routers are OSI\255only, and) W
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47.2 0 32 (some routers are dual. The specific topological restrictions which apply in this latter case are de\255) W
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35.8 0 32 (scribed in detail in section ) W
35.8 0 32 (1.4 \() W
35.8 0 32 (\026) W
35.8 0 32 (Support of Mixed Routing Domains) W
35.8 0 32 (\027) W
35.8 0 32 (\). The use of IS\255IS for sup\255) W
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(port of pure OSI domains is specified in [1].) h
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170.2 0 32 (This protocol specification does not constrain which network management protocol\(s\) may be) W
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173.4 0 32 (used to manage IS\255IS\255based routers. Management information bases \(MIBs\) for managing IP\255) W
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82.2 0 32 (only, OSI\255only, and dual routers, compatible with CMIP, CMOT, and/or SNMP, are the subject) W
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(of a separate, companion document [8].) h
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(1.2 ) h
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(Overview of the ISO IS\255IS Protocol) h
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62.5 0 32 (The IS\255IS Routing Protocol has been developed in ISO to provide routing for pure OSI environ\255) W
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75.7 0 32 (ments. In particular, IS\255IS is designed to work in conjunction with ISO 8473 \(The ISO Connec\255) W
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81.2 0 32 (tionless Network Layer Protocol [2]\), and ISO 9542 \(The ISO End System to Intermediate Sys\255) W
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158.0 0 32 (tem Protocol [3]\). This section briefly describes the manner in which IS\255IS is used to support) W
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195.0 0 32 (pure OSI environments. Enhancements for support of IP and dual environments are specified) W
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(elsewhere in this report.) h
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113.2 0 32 (In IS\255IS, the network is partitioned into ) W
113.2 0 32 (\026) W
113.2 0 32 (routing domains) W
113.2 0 32 (\027) W
113.2 0 32 (. The boundaries of routing domains) W
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177.5 0 32 (are defined by network management, by setting some links to be ) W
177.5 0 32 (\026) W
177.5 0 32 (exterior links) W
177.5 0 32 (\027) W
177.5 0 32 (. If a link is) W
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(marked as ) h
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(exterior) h
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(, no IS\255IS routing messages are sent on that link.) h
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55.3 0 32 (Currently, ISO does not have a standard for inter\255domain routing \(i.e., for routing between sepa\255) W
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133.5 0 32 (rate autonomous routing domains\). Instead, manual configuration is used. The link is statically) W
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33.8 0 32 (configured with the set of address prefixes reachable via that link, and with the method by which) W
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76.1 0 32 (they can be reached \(such as the DTE address to be dialed to reach that address, or the fact that) W
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(the DTE address should be extracted from the IDP portion of the ISO address\). ) h
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125.9 0 32 (OSI IS\255IS routing makes use of two\255level hierarchical routing. A routing domain is partitioned) W
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98.5 0 32 (into ) W
98.5 0 32 (\026) W
98.5 0 32 (areas) W
98.5 0 32 (\027) W
98.5 0 32 (. Level 1 routers know the topology in their area, including all routers and end sys\255) W
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123.2 0 32 (tems in their area. However, level 1 routers do not know the identity of routers or destinations) W
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65.3 0 32 (outside of their area. Level 1 routers forward all traffic for destinations outside of their area to a) W
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41.4 0 32 (level 2 router in their area. Similarly, level 2 routers know the level 2 topology, and know which) W
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28.2 0 32 (addresses are reachable via each level 2 router. However, level 2 routers do not need to know the) W
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76.9 0 32 (topology within any level 1 area, except to the extent that a level 2 router may also be a level 1) W
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20.5 0 32 (router within a single area. Only level 2 routers can exchange data packets or routing information) W
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(directly with external routers located outside of the routing domains. ) h
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(Figure 1 \255 ) h
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(ISO Hierarchical Address Structure) h
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111.3 0 32 (As illustrated in figure ) W
111.3 0 32 (1, ISO addresses are subdivided into the Initial Domain Part \(IDP\), and) W
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39.9 0 32 (the Domain Specific Part \(DSP\). The IDP is the part which is standardized by ISO, and specifies) W
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21.1 0 32 (the format and authority responsible for assigning the rest of the address. The DSP is assigned by) W
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224.1 0 32 (whatever addressing authority is specified by the IDP. The DSP is further subdivided into a) W
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20.6 0 32 (\026) W
20.6 0 32 (High Order Part of DSP) W
20.6 0 32 (\027) W
20.6 0 32 ( \(HO\255DSP\), a system identifier \(ID\), and an NSAP selector \(SEL\). The) W
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84.7 0 32 (HO\255DSP may use any format desired by the authority which is identified by the IDP. Together,) W
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15.7 0 32 (the combination of [IDP, HO\255DSP] identify both the routing domain and the area within the rout\255) W
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122.2 0 32 (ing domain. The combination of [IDP,HO\255DSP] may therefore be referred to as the ) W
122.2 0 32 (\026) W
122.2 0 32 (Area Ad\255) W
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