rfc1245.ps

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

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72 675 540 720 R
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(Network Working Group) 72 712 T
(J. Moy, Editor) 470.7 712 T
(Request for Comments: 1245) 72 698 T
(Proteon, Inc.) 478.38 698 T
(July 1991) 493.02 684 T
72 72 540 83.95 R
7 X
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([Moy]) 72 75.95 T
([Page 1]) 499.7 75.95 T
72 117 540 603 R
7 X
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1 F
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(OSPF protocol analysis) 192.72 587 T
2 F
(Status of this Memo) 72 514.33 T
0 F
-0.23 (This memo provides information for the Internet community) 72 487 P
-0.23 (. It does not specify any Internet stan-) 360.42 487 P
(dard. Distribution of this memo is unlimited.) 72 473 T
2 F
(Abstract) 72 447 T
0 F
-0.11 (This is the \336rst of two reports on the OSPF protocol. These reports are required by the IAB/IESG ) 72 421 P
(in order for an Internet routing protocol to advance to Draft Standard Status. OSPF is a TCP/IP ) 72 407 T
-0.28 (routing protocol, designed to be used internal to an Autonomous System \050in other words, OSPF is ) 72 393 P
(an Interior Gateway Protocol\051.) 72 379 T
-0.09 (V) 72 353 P
-0.09 (ersion 1 of the OSPF protocol was published in RFC 1) 79.33 353 P
-0.09 (131. Since then OSPF version 2 has been ) 339.85 353 P
-0.22 (developed. V) 72 339 P
-0.22 (ersion 2 has been documented in RFC 1247. The changes between version 1 and ver-) 134.4 339 P
-0 (sion 2 of the OSPF protocol are explained in Appendix F of RFC 1247. It is OSPF V) 72 325 P
-0 (ersion 2 that ) 477.72 325 P
(is the subject of this report.) 72 311 T
(This report attempts to summarize the key features of OSPF V2. It also attempts to analyze how ) 72 285 T
(the protocol will perform and scale in the Internet.) 72 271 T
(Please send comments to ospf@trantor) 72 245 T
(.umd.edu.) 258.27 245 T
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72 702 540 720 R
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(RFC 1245) 72 712 T
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(July 1991) 493.02 712 T
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([Moy]) 72 73 T
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72 108 540 684 R
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(T) 72 673.33 T
(able of Contents) 81.19 673.33 T
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(1.0) 72 650 T
(Introduction) 108 650 T
(..............................................................................................................) 167.91 650 T
(3) 498 650 T
1 F
(1.1) 108 635.33 T
(Acknowledgments) 144 635.33 T
(...............................................................................................................) 219.88 635.33 T
(3) 499 635.33 T
0 F
(2.0) 72 616 T
(Key features of the OSPF protocol) 108 616 T
(..........................................................................) 275.85 616 T
(4) 498 616 T
(3.0) 72 596 T
(Cost of the protocol) 108 596 T
(..................................................................................................) 203.89 596 T
(7) 498 596 T
1 F
(3.1) 108 581.33 T
( Operational data) 144 581.33 T
(.................................................................................................................) 214.88 581.33 T
(7) 499 581.33 T
(3.2) 108 567.33 T
(Link bandwidth) 144 567.33 T
(...................................................................................................................) 209.88 567.33 T
(9) 499 567.33 T
(3.3) 108 553.33 T
(Router memory) 144 553.33 T
(....................................................................................................................) 207.39 553.33 T
(9) 499 553.33 T
(3.4) 108 539.33 T
(Router CPU) 144 539.33 T
(.......................................................................................................................) 194.89 539.33 T
(10) 494.01 539.33 T
(3.5) 108 525.33 T
(Role of Designated Router) 144 525.33 T
(................................................................................................) 252.36 525.33 T
(1) 494.38 525.33 T
(1) 499 525.33 T
(3.6) 108 511.33 T
(Summary) 144 511.33 T
(...........................................................................................................................) 184.9 511.33 T
(1) 494.38 511.33 T
(1) 499 511.33 T
0 F
(4.0) 72 492 T
(Suitable environments) 108 492 T
(............................................................................................) 215.88 492 T
(13) 492.01 492 T
(5.0) 72 472 T
(Unsuitable environments) 108 472 T
(.......................................................................................) 230.87 472 T
(13) 492.01 472 T
(6.0) 72 452 T
(Reference Documents) 108 452 T
(............................................................................................) 215.88 452 T
(14) 492.01 452 T
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(1.0  Intr) 72 673.33 T
(oduction) 127.23 673.33 T
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-0.02 (This document addresses, for OSPF V2, the requirements set forth by the IAB/IESG for an Inter-) 72 646 P
-0.19 (net routing protocol to advance to Draft Standard state. This requirements are brie\337y summarized ) 72 632 P
(below) 72 618 T
(. The remaining sections of this report document how OSPF V2 satis\336es these require-) 100.53 618 T
(ments:) 72 604 T
(\245) 72 584 T
(What are the key features and algorithms of the protocol?) 85.54 584 T
(\245) 72 564 T
(How much link bandwidth, router memory and router CPU cycles does the protocol consume ) 85.54 564 T
(under normal conditions?) 85.54 550 T
(\245) 72 530 T
(For these metrics, how does the usage scale as the routing environment grows? This should ) 85.54 530 T
(include topologies at least an order of magnitude lar) 85.54 516 T
(ger than the current environment.) 335.14 516 T
(\245) 72 496 T
(What are the limits of the protocol for these metrics? \050i.e., when will the routing protocol ) 85.54 496 T
(break?\051 ) 85.54 482 T
(\245) 72 462 T
(For what environments is the protocol well suited, and for what is it not suitable? ) 85.54 462 T
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(1.1  Acknowledgments) 72 428.67 T
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-0.03 (The OSPF protocol has been developed by the OSPF W) 72 402 P
-0.03 (orking Group of the Internet Engineering ) 339.64 402 P
(T) 72 388 T
(ask Force. ) 78.49 388 T
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(July 1991) 493.02 712 T
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([Moy]) 72 73 T
([Page 4]) 499.7 73 T
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(2.0  Key featur) 72 673.33 T
(es of the OSPF pr) 172.97 673.33 T
(otocol) 293.49 673.33 T
0 F
(This section summarizes the key features of the OSPF protocol. OSPF is an) 72 646 T
4 F
( Internal gateway ) 434.78 646 T
-0.2 (pr) 72 632 P
-0.2 (otocol) 83.78 632 P
0 F
-0.2 (; it is designed to be used internal to a single Autonomous System. OSPF uses) 114.42 632 P
4 F
-0.2 ( link-state ) 486.43 632 P
-0.36 (or SPF-based) 72 618 P
0 F
-0.36 ( technology \050as compared to the distance-vector or Bellman-Ford technology found ) 140.6 618 P
-0.48 (in routing protocols such as RIP\051. Individual ) 72 604 P
4 F
-0.48 (link state advertisements \050LSAs\051) 285.2 604 P
0 F
-0.48 ( describe pieces of ) 449.99 604 P
-0.13 (the OSPF routing domain \050Autonomous System\051. These LSAs are \337ooded throughout the routing ) 72 590 P
(domain, forming the ) 72 576 T
4 F
(link state database) 173.27 576 T
0 F
(. Each router has an identical link state database; syn-) 268.56 576 T
(chronization of link state databases is maintained via a ) 72 562 T
4 F
(r) 336.81 562 T
(eliable \337ooding algorithm) 341.92 562 T
0 F
(. From this ) 473.2 562 T
(link state database, each router builds a routing table by calculating a shortest-path tree, with the ) 72 548 T
(root of the tree being the calculating router itself. This calculation is commonly referred to as the ) 72 534 T
4 F
(Dijkstra pr) 72 520 T
(ocedur) 129.41 520 T
(e) 164.51 520 T
0 F
(.) 169.83 520 T
(Link state advertisements are small. Each advertisement describes a small pieces of the OSPF ) 72 494 T
(routing domain, namely either: the neighborhood of a single router) 72 480 T
(, the neighborhood of a single ) 391.97 480 T
(transit network, a single inter) 72 466 T
(-area route \050see below\051 or a single external route.) 212 466 T
(The other key features of the OSPF protocol are:) 72 440 T
(\245) 72 420 T
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-0.31 (Adjacency bringup) 85.54 420 P
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-0.31 (. ) 183.51 420 P
4 F
-0.31 (Certain pairs of OSPF r) 189.2 420 P
-0.31 (outers become \322adjacent\323) 311.01 420 P
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-0.31 (. As an adjacency is ) 442.96 420 P
(formed, the two routers synchronize their link state databases by ) 85.54 406 T
4 F
(exchanging database sum-) 397.64 406 T
(maries) 85.54 392 T
0 F
( in the form of OSPF Database Exchange packets. Adjacent routers then maintain syn-) 120.17 392 T
(chronization of their link state databases through the ) 85.54 378 T
4 F
(r) 340.02 378 T
(eliable \337ooding algorithm) 345.13 378 T
0 F
(. Routers ) 476.41 378 T
-0.27 (connected by serial lines always become adjacent. On multi-access networks \050e.g., ethernets or ) 85.54 364 P
(X.25 PDNs\051, all routers attached to the network become adjacent to both the Designated ) 85.54 350 T
(Router and the Backup Designated router) 85.54 336 T
(.) 283.73 336 T
(\245) 72 316 T
4 F
-0.02 (Designated r) 85.54 316 P
-0.02 (outer) 150.26 316 P
-0.02 (.) 176.46 316 P
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-0.02 ( A Designated Router is elected on all multi-access networks \050e.g., ether-) 179.46 316 P
(nets or X.25 PDNs\051. The network\325) 85.54 302 T
(s Designated Router ) 250.42 302 T
4 F
(originates the network LSA) 350.69 302 T
0 F
( describ-) 492.27 302 T
(ing the network\325) 85.54 288 T
(s local environment. It also plays a ) 164.15 288 T
4 F
(special r) 334.04 288 T
(ole in the \337ooding algorithm) 376.8 288 T
0 F
(, ) 521.4 288 T
(since all routers on the network are synchronizing their link state databases by sending and ) 85.54 274 T
(receiving LSAs to/from the Designated Router during the \337ooding process.) 85.54 260 T
(\245) 72 240 T
4 F
-0.46 (Backup Designated Router) 85.54 240 P
0 F
-0.46 (. A Backup Designated Router is elected on multi-access networks ) 221.87 240 P
(to speed/ease the transition of Designated Routers when the current Designated Router disap-) 85.54 226 T
(pears. In that event, the Backup DR takes over) 85.54 212 T
(, and does not need to go through the adjacency ) 308.22 212 T
-0.13 (bringup process on the LAN \050since it already had done this in its Backup capacity\051. Also, even ) 85.54 198 P
(before the disappearance of the Designated Router is noticed, the Backup DR will enable the ) 85.54 184 T
(reliable \337ooding algorithm to proceed in the DR\325) 85.54 170 T
(s absence.) 320.39 170 T
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(RFC 1245) 72 712 T
(OSPF protocol analysis) 249.36 712 T
(July 1991) 493.02 712 T
72 69.05 540 81 R
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([Moy]) 72 73 T
([Page 5]) 499.7 73 T
72 108 540 684 R
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(\245) 72 676 T
4 F
(Non-br) 85.54 676 T