The NSAP address
A network entity title (NET) is an NSAP with an n-selector of zero.
AFI 为 1 byte 通常 lab 都用 49 (保留用)
System ID 为 6 bytes ( 就是 MAC Address 但也可以自订)
NSEL 在这为 00 1 byte
Area Address 为可变长度字段 1byte ~ 13 bytes
例: 49.0001.1111.1111.1111.00
1111.1111.1111 为 MAC Address 值 49.0001 为 Area Address
!
interface Ethernet0
ip address 172.16.12.1 255.255.255.0
ip router isis
!--- Assigns IP address to interface Ethernet0
!--- and enables IS-IS for IP on the interface.
!
router isis
net 49.0001.1111.1111.1111.00
!
!--- Enables the IS-IS PRocess on the router,
!--- and assigns area and system ID to router.
要激活 ISIS 的 IP routing 只要 3 个指令
Router(config)#router isis
Router(config-router)#net 49.0001.1111.1111.1111.00
在要激活 IS-IS routing 的 interface 上
Router(config-if)#ip router isis
如此就激活了 ISIS
用这次做 Lab 的 topology 来做解说
R1 是 Area 49.0001 上的 ABR
与 R2 用 Level 1 的 routing
与 R3 用 Level 2 的 routing
!
hostname R1
!
enable passWord cisco
!
ip subnet-zero
clns routing
!----有激活 clns 的 routing
!
!
interface Ethernet0
no ip address
no ip directed-broadcast
shutdown
!
interface Ethernet1
no ip address
no ip directed-broadcast
shutdown
!
interface Serial0
ip address 192.168.1.2 255.255.255.0
no ip directed-broadcast
ip router isis
!----激活 ip routing
no ip mroute-cache
clockrate 1300000
clns router isis
!----激活 clns routing
isis circuit-type level-1
!----宣告 serial 0 用 level-1 routing
!
interface Serial1
ip address 10.10.10.1 255.255.255.0
no ip directed-broadcast
ip router isis
clockrate 1300000
clns router isis
isis circuit-type level-2-only
!----宣告 serial 1 用 level-2 routing
!
router isis
net 49.0001.1111.1111.1111.00
!----激活 isis routing process 与 输入 nsap address
!
ip classless
!
!
!
line con 0
transport input none
line aux 0
line vty 0 4
password cisco
login
!
end
R1#
R1#
R1#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
172.168.0.0/24 is subnetted, 1 subnets
i L1 172.168.1.0 [115/20] via 192.168.1.1, Serial0
172.31.0.0/24 is subnetted, 1 subnets
i L2 172.31.1.0 [115/50] via 10.10.10.2, Serial1
10.0.0.0/24 is subnetted, 2 subnets
C 10.10.10.0 is directly connected, Serial1
i L2 10.10.20.0 [115/30] via 10.10.10.2, Serial1
C 192.168.1.0/24 is directly connected, Serial0
i L2 192.168.2.0/24 [115/20] via 10.10.10.2, Serial1
i L2 192.168.3.0/24 [115/40] via 10.10.10.2, Serial1
R1#
L1 代表由 Level-1 routing 学来的
L2 由 Level-2 routing 学来
ps. Cisco router 预设会把 Level-1 与 Level-2 同时激活
Show Level-1 Routing Table
R1#sh isis route
IS-IS Level-1 Routing Table - version 15
System Id Next-Hop Interface SNPA Metric State
1111.1111.1111 --
2222.2222.2222 2222.2222.2222 Se0 *HDLC* 10 Up
R1#
Show Level-2 Routing Table
R1#sh clns route
CLNS Prefix Routing Table
49.0001.1111.1111.1111.00, Local NET Entry
49.0003 [110/30]
via 3333.3333.3333, IS-IS, Up, Serial1
49.0002 [110/10]
via 3333.3333.3333, IS-IS, Up, Serial1
49.0001 [110/0]
via 1111.1111.1111, IS-IS, Up
R1#
R1#sh isis topology
IS-IS paths to level-1 routers
System Id Metric Next-Hop Interface SNPA
1111.1111.1111 --
2222.2222.2222 10 2222.2222.2222 Se0 *HDLC*
IS-IS paths to level-2 routers
System Id Metric Next-Hop Interface SNPA
1111.1111.1111 --
3333.3333.3333 10 3333.3333.3333 Se1 *HDLC*
4444.4444.4444 30 3333.3333.3333 Se1 *HDLC*
6666.6666.6666 20 3333.3333.3333 Se1 *HDLC*
R1#
R1#
R1#ping 172.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.168.1.1, timeout is 2 seconds:
!!!!!
SUCcess rate is 100 percent (5/5), round-trip min/avg/max = 4/5/8 ms
