ISP采用的 ISIS链接状态路由协议
<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />ISIS
特点：较快的会聚速度，高稳定性，可扩展性 默认度量值都是10
NSAP地址 相当于ospf里的router-id 都是唯一的！通过LSP获取区域路径]
network-entity的格式：Area = 49.0001, System ID = aaaa.bbbb.cccc, NSEL = 00
area：为可变长度部分，范围为1-13个字节。
System ID：是IS或ES在区域内的唯一标识，总共为6个字节，可以使用MAC地址或由IP地址转化得到。
NSEL：service identifier，共一个字节。（00表示在ip环境）
AFI=49为私有地址空间，类似于私有的IP地址
R1>en
R1#conf t
R1(config)#inter loop 0 配置环回口
R1(config-if)#ip address 1.1.1.1 255.255.255.255
R1(config-if)#no shut
R1(config-if)#inter f0/0 物理地址
R1(config-if)#ip address 192.168.12.1 255.255.255.0
R1(config-if)#no shut
R1(config-if)#end
R1(config)#router isis
R1(config-router)#net 49.0001.0001.0001.0001.00 ISIS NET地址
R1(config-router)#ex
R1(config)#inter f0/0 运 行isis协议
R1(config-if)#ip router isis
R1(config-if)#inter loop 0
R1(config-if)#ip router isis
R1(config-if)#end
R1#show isis neighbors 查看isis邻居关系 发现有2个 优化一下
System Id Type Interface IP Address State Holdtime Circuit Id
R2 L1 Fa0/0 192.168.12.2 UP 8 R2.01
R2 L2 Fa0/0 192.168.12.2 UP 8 R2.01
R1#conf t
R1(config)#router isis
R1(config-router)#is-type level-1 把类型改成1
R1(config-router)#end
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
R1#show isi neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
R1#show isi neighbors
System Id Type Interface IP Address State Holdtime Circuit Id 发现只有一个了
R2 L1 Fa0/0 192.168.12.2 UP 9 R2.01
R2配置：
R2>en
R2#conf t
R2(config)#inter f0/0
R2(config-if)#ip address 192.168.12.2 255.255.255.0
R2(config-if)#no shut
R2(config-if)#inter f0/1
R2(config-if)#ip address 192.168.23.2 255.255.255.0
R2(config-if)#inter loop 0
R2(config-if)#ip address 2.2.2.2 255.255.255.255
R2(config-if)#no shut
R2(config-if)#ex
R2(config)#router isis
R2(config-router)#net 49.0001.0002.0002.0002.00
R2(config-router)#ex
R2(config)#inter f0/0
R2(config-if)#ip router isis
R2(config-if)#inter f0/1
R2(config-if)#ip router isis
R2(config-if)#int loop 0
R2(config-if)#ip router isis
R3配置
R3>en
R3#conf t
R3(config)#inter loop 0
R3(config-if)#ip address 3.3.3.3 255.255.255.255
R3(config-if)#no shut
R3(config-if)#inter f0/0
R3(config-if)#ip address 192.168.23.3 255.255.255.0
R3(config-if)#no shut
R3(config-if)#inter f0/1
R3(config-if)#ip address 192.168.34.3 255.255.255.0
R3(config-if)#no shut
R3(config)#router isis
R3(config-router)#net 49.0002.0003.0003.0003.00
R3(config-router)#ex
R3(config)#inter f0/0
R3(config-if)#ip router isis
R3(config-if)#inter f0/1
R3(config-if)#ip router isis
R3(config-if)#inter loop 0
R3(config-if)#ip router isis
R3(config-if)#end
R3#show ip route
Codes: C - connected, S - static, 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
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
i L2 192.168.12.0/24 [115/20] via 192.168.23.2, FastEthernet0/0
1.0.0.0/32 is subnetted, 1 subnets
i L2 1.1.1.1 [115/30] via 192.168.23.2, FastEthernet0/0
2.0.0.0/32 is subnetted, 1 subnets
i L2 2.2.2.2 [115/20] via 192.168.23.2, FastEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
4.0.0.0/32 is subnetted, 1 subnets
i L1 4.4.4.4 [115/20] via 192.168.34.4, FastEthernet0/1
C 192.168.23.0/24 is directly connected, FastEthernet0/0
C 192.168.34.0/24 is directly connected, FastEthernet0/1
R3#write
Building configuration...
[OK]
R4配置：
R4>en
R4#conf t
R4(config)#inter f0/0
R4(config-if)#ip address 192.168.34.4 255.255.255.0
R4(config-if)#no shut
R4(config-if)#inter loop 0
R4(config-if)#ip address 4.4.4.4 255.255.255.255
R4(config-if)#no shut
R4(config-if)#ex
R4(config)#router isis
R4(config-router)#net 49.0002.0004.0004.0004.00
R4(config-router)#ex
R4(config)#inter f0/0
R4(config-if)#ip router isis
R4(config-if)#inter loop 0
R4(config-if)#ip router isis
R4(config-if)#end
R4#show ip rout
*Mar 1 00:11:46.507: %SYS-5-CONFIG_I: Configured from console by console
R4#show ip rout
Codes: C - connected, S - static, 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
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is 192.168.34.3 to network 0.0.0.0
3.0.0.0/32 is subnetted, 1 subnets
i L1 3.3.3.3 [115/20] via 192.168.34.3, FastEthernet0/0
4.0.0.0/32 is subnetted, 1 subnets
C 4.4.4.4 is directly connected, Loopback0
i L1 192.168.23.0/24 [115/20] via 192.168.34.3, FastEthernet0/0
C 192.168.34.0/24 is directly connected, FastEthernet0/0
i*L1 0.0.0.0/0 [115/10] via 192.168.34.3, FastEthernet0/0
R4#ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
R4#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
R3 L1 Fa0/0 192.168.34.3 UP 29 R4.01
R3 L2 Fa0/0 192.168.34.3 UP 26 R4.01
R4#conf t
R4(config)#router isis
R4(config-router)#is-type level-1
R4(config-router)#end
R4#end
*Mar 1 00:15:09.095: %SYS-5-CONFIG_I: Configured from console by console
R4#ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
.....
R4#ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
U.U.!
Success rate is 20 percent (1/5), round-trip min/avg/max = 120/120/120 ms
R4#ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 48/70/108 ms
R4#
R4#write
Building configuration...
[OK]
S-IS路由器角色和信息交换
⒈ L1，Level 1，只负责区域内路由，类似于OSPF的内部非骨干路由器。只能通告给L1和L1/L2。
⒉ L2，Level 2，只负责区域间路由，类似于OSPF的骨干
路由器
。L2和L1/L2。
⒊L1/L2，Level 1-2，同时负责区域内和区域间路由，类似于OSPF的ABR。包含两个独立的Level 1 和Level 2数据库。但它不向L1路由器通告L2路由，所以L1路由器不会学到区域外的路由，这有点像OSPF的完全末节区域。
NET算法 例如：202.106.1.1 32位表示成48位 202.106.001.001 2021.0600.1001