拓扑就是书上的拓扑了.
在RID5.5.5.5的路由器上重分发RIP路由信息到OSPF中,5,5,5,5是个ASBR.
1.1.1.1和2.2.2.2是ABR连接区域1和0,5.5.5.5路由器接口位于区域0中
下面的是P1R3路由器上,在没有被配置为末节区域前的LSA情况:
r3-2514#show ip ospf data
OSPF Router with ID (3.3.3.3) (Process ID 1)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 273 0x80000009 0x000839 3
2.2.2.2 2.2.2.2 218 0x8000000A 0x003403 3
3.3.3.3 3.3.3.3 259 0x80000006 0x00859D 3
4.4.4.4 4.4.4.4 181 0x80000006 0x00B366 3
Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.1.1.1 1.1.1.1 273 0x80000004 0x009085
10.1.2.2 2.2.2.2 218 0x80000004 0x00B156
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
172.31.1.0 1.1.1.1 1031 0x80000006 0x009E88
172.31.1.0 2.2.2.2 970 0x80000004 0x0084A0
Summary ASB Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
5.5.5.5 1.1.1.1 14 0x80000003 0x00F4EC
5.5.5.5 2.2.2.2 1997 0x80000002 0x00D806
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
5.0.0.0 5.5.5.5 1584 0x80000002 0x000E78 0
6.0.0.0 5.5.5.5 1070 0x80000002 0x000184 0
192.168.1.0 5.5.5.5 1591 0x80000002 0x00928E 0
下面输出的是配置为STUB后的情况:
r3-2514#show ip ospf database
OSPF Router with ID (3.3.3.3) (Process ID 1)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 22 0x8000000D 0x0062DA 3
2.2.2.2 2.2.2.2 12 0x8000000E 0x00AA51 4
3.3.3.3 3.3.3.3 11 0x8000000A 0x00DF3F 3
4.4.4.4 4.4.4.4 13 0x80000009 0x001007 3
Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.1.1.1 1.1.1.1 3606 0x80000005 0x008E86
10.1.1.3 3.3.3.3 41 0x80000001 0x0044CC
10.1.2.2 2.2.2.2 3605 0x80000005 0x00AF57
10.1.2.4 4.4.4.4 11 0x80000001 0x00659D
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
0.0.0.0 1.1.1.1 186 0x80000001 0x0093A6
0.0.0.0 2.2.2.2 65 0x80000001 0x0075C0
172.31.1.0 1.1.1.1 189 0x80000007 0x00BA6D
172.31.1.0 2.2.2.2 68 0x80000005 0x00A085
注意看红色部分的在末节区域里不见了,也就是说在末节区域,4类汇总LSA和5类外部ASA都进不来,3类汇总LSA可以进来.这与书上的3.4类汇总都进不来有差别.书上看来的说的有问题.但此时也注意到,3类汇总里多了2个目标网络是0.0.0.0的汇总LSA,这是ABR自动产生的.
顺带看下,此时路由表的情况:
r3-2514#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 10.1.1.1 to network 0.0.0.0
C 3.0.0.0/8 is directly connected, Loopback0
172.31.0.0/24 is subnetted, 1 subnets
O IA 172.31.1.0 [110/74] via 10.1.1.1, 00:03:46, Ethernet0
10.0.0.0/24 is subnetted, 4 subnets
C 10.1.3.0 is directly connected, Serial1
O 10.1.2.0 [110/74] via 10.1.3.4, 00:03:46, Serial1
C 10.1.1.0 is directly connected, Ethernet0
O 10.1.0.0 [110/74] via 10.1.1.1, 00:03:46, Ethernet0
O*IA 0.0.0.0/0 [110/11] via 10.1.1.1, 00:03:46, Ethernet0
此时R3上没有了到外部AS中的路由条目,取而代之的是一条默认路由.此时区域间路由还存在!
下面的是没有配置为末节区域时候的路由表
r3-2514#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
C 3.0.0.0/8 is directly connected, Loopback0
O E2 5.0.0.0/8 [110/20] via 10.1.1.1, 00:00:04, Ethernet0
O E2 6.0.0.0/8 [110/20] via 10.1.1.1, 00:00:04, Ethernet0
172.31.0.0/24 is subnetted, 1 subnets
O IA 172.31.1.0 [110/74] via 10.1.1.1, 00:00:04, Ethernet0
10.0.0.0/24 is subnetted, 4 subnets
C 10.1.3.0 is directly connected, Serial1
O 10.1.2.0 [110/74] via 10.1.3.4, 00:00:04, Serial1
C 10.1.1.0 is directly connected, Ethernet0
O 10.1.0.0 [110/74] via 10.1.1.1, 00:00:05, Ethernet0
O E2 192.168.1.0/24 [110/20] via 10.1.1.1, 00:00:05, Ethernet
===============================================
看配置为绝对末节区域后 情况如何
r3-2514#show ip ospf data
OSPF Router with ID (3.3.3.3) (Process ID 1)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
1.1.1.1 1.1.1.1 189 0x80000013 0x0056E0 3
2.2.2.2 2.2.2.2 169 0x80000015 0x0080AB 3
3.3.3.3 3.3.3.3 168 0x80000010 0x00D345 3
4.4.4.4 4.4.4.4 170 0x8000000E 0x00060C 3
Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.1.1.3 3.3.3.3 203 0x80000004 0x003ECF
10.1.2.4 4.4.4.4 168 0x80000005 0x005DA1
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
0.0.0.0 1.1.1.1 214 0x80000001 0x0093A6
0.0.0.0 2.2.2.2 200 0x80000001 0x0075C0
这里依然有3类汇总LSA 但显然LINKID已经变成了默认路由里的目标网络号了,也就是说ABR不再通告的是真正具体目标网络的汇总LSA了,而是自动产生一条默认路由的汇总.可以理解为,真正的3类LSA过不来了.
看此时的路由表情况:
r3-2514#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 10.1.1.1 to network 0.0.0.0
C 3.0.0.0/8 is directly connected, Loopback0
10.0.0.0/24 is subnetted, 4 subnets
C 10.1.3.0 is directly connected, Serial1
O 10.1.2.0 [110/84] via 10.1.1.1, 00:00:06, Ethernet0
C 10.1.1.0 is directly connected, Ethernet0
O 10.1.0.0 [110/74] via 10.1.1.1, 00:00:06, Ethernet0
O*IA 0.0.0.0/0 [110/11] via 10.1.1.1, 00:00:06, Ethernet0
这次路由表更彻底,区域间路由也被默认路由代替了.
总结:
末节区域 4类/5类过不来
绝对末节区域 3 4 5 都过不来
但不管是哪种末节区域,由ABR自动产生的目标网络为0.0.0.0的汇总LSA都会存在.