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IS-IS 网络设计方案

2019-11-04 21:26:59
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  关于IS-IS 的历史
  
  IS-IS was ad hoc in its evolution, whereas OSPF was more formal:
  
  1985: Originally called DECnet Phase V Routing
  
  1988: Adopted by ISO and renamed IS-IS
  
  1990: Publication of RFC 1142, "OSI IS-IS Intradomain Routing PRotocol"
  
  1990: Publication of RFC 1195, "Use of OSI IS-IS for Routing in TCP/ip and Dual Environments"
  
  1991: Cisco IOS Software starts supporting IS-IS
  
  1995: ISPs start adopting IS-IS
  
  2000: Publication of IETF draft "IS-IS Extensions for Traffic Engineering"
  
  2001: Publication of IETF draft "IS-IS Extensions in Support of Generalized MPLS"
  
  
  谁来使用IS-IS
  IS-IS主要是电信运营商和大型ISP所普遍采用的一种路由协议。ISP在IGP协议中大量采用IS-IS或者OSPF协议,至于这两种协议哪种更有优势,只能说每个网络工程师都有自己所长,有些习惯使用OSPF,有些就善于组建IS-IS的网络。
  
  面向对象连接和非面向对象连接
  面向对象连接就是在数据通过前首先要建立连接,而非面向对象连接则可以不需要建立连接直接发送数据
  
  CLNS
  Connectionless Network Service (CLNS)—CLNS performs datagram transport and does not require a circuit to be established before data is transmitted.
  
  IS-IS
  Variable-length subnet masks (VLSMs). The mask and the prefix are sent in the routing updates.
  
  Redistribution of IP routes into and out of IS-IS.
  
  Summarization of IP routes.
  
  Level 1 ISs are responsible for routing to ESs inside an area. This is similar to OSPF internal nonbackbone routers in a totally stubby area.
  
  Level 2 ISs route between areas only. This is similar to internal backbone routers in OSPF.
  
  Level 1–2 ISs route between areas and the backbone. They participate in the Level 1 intra-area routing and the Level 2 interarea routing. This is the equivalent of Area Border Routers (ABRs) in OSPF.
  
  源码:----------------------------------------------------------
  
  NSAP Examples
  The following examples illustrate how an NSAP address is interpreted by IS-IS and ISO-IGRP.
  
  The NSAP 49.0001.aaaa.bbbb.cccc.00 consists of the following:
  
  For IS-IS:
  
  Area = 49.0001
  
  System ID = aaaa.bbbb.cccc
  
  N-selector = 00
  
  For ISO-IGRP:
  
  Domain = 49
  
  Area = 0001
  
  System ID = aaaa.bbbb.cccc
  
  N-selector = ignored by ISO-IGRP
  
  The NSAP 39.0f01.0002.0000.0c00.1111.00 consists of the following:
  
  For IS-IS:
  
  Area = 39.0f01.0002
  
  System ID = 0000.0c00.1111
  
  N-selector = 00
  
  For ISO-IGRP:
  
  Domain = 39.0f01
  
  Area = 0002
  
  System ID = 0000.0c00.1111
  
  N-selector = ignored by ISO-IGRP
  
  --------------------------------------------------------------------------------
  基本配置
  hostname R1
  
  !
  interface Serial0
  ip address 192.168.120.1 255.255.255.0
  ip router isis
  !
  router isis
  net 49.0001.1921.6800.1005.00
  
  is-type level-1
  
  !
  !backbone_r1 EIGRP configuration exercise configuration
  !
  ! This file is designed to be copied and pasted into a router that already
  ! has the previous BSCN configuration files loaded, at the # prompt
  !
  conf t
  !
  no router isis
  no clns routing
  !
  access-list 1 permit 172.16.10.0
  access-list 1 permit 172.16.11.0
  route-map passext permit 10
  match ip address 1
  !
  router eigrp 200
  redistribute connected metric 10000 100 255 1 1500 route-map passext
  network 10.0.0.0
  !进入讨论组讨论。


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