从实验现象分析OSPF多区域的LSA传播及路由学习
1.1 组网拓扑
1.2 实验目标
按上图，使用OSPF多区域实现全网连通性。
按上图，使用OSPF多区域实现全网路由
掌握：分析各路由器的OSPF邻居表、全局路由表、OSPF LSDB ,RIP Datobase.
理解：分析172.16.3.0/24这条路由是怎样从RT3传播至RT4的。
理解：分析172.17.4.0/24这条路由是怎样从RT4传播至RT3的。
掌握：OSPF区域路由汇总与外部路由汇总。
掌握：OSPF stub、完全stub、NSSA、完全NSSA区域的配置与路由、LSA分析。
掌握：Area2为NSSA时，分析172.17.4.0/24这条路由是怎样从RT4传播至RT3的。
掌握：标准区域、stub、完全stub、NSSA、完全NSSA区域的LSA及缺省路由发布。
1.3 实验步骤
基本信息配置
接口配置及链路测试
路由配置及测试
OSPF LSA传播及计算分析(LSA 3,LSA 5,缺省路由)
OSPF路由汇总配置与分析(区域路由汇总,外部路由汇总)
OSPF特殊区域配置与分析(stub,完全stub,NSSA,完全NSSA)
Ospf 认证
Ospf V-LINK
1.4 路由的配置及调测
R1:
router ospf 1
passive-interface Ethernet0/0
network 10.0.0.1 0.0.0.0 area 0
network 172.16.17.0 0.0.0.3 area 0
network 172.17.1.0 0.0.0.255 area 1
network 172.17.13.0 0.0.0.3 area 1
R2:
router ospf 1
redistribute rip metric 1000 metric-type 1 subnets //将全局路由表中的RIP重发布到ospf中
passive-interface Ethernet0/0
network 10.0.0.2 0.0.0.0 area 2
network 172.18.2.0 0.0.0.255 area 2
network 172.18.28.0 0.0.0.3 area 2
default-information originate
router rip
version 2
redistribute ospf 1 metric 5 //将全局路由表中的ospf路由重发布到RIP中
network 192.168.24.0
no auto-summary
R3:
router ospf 1
passive-interface Ethernet0/0
network 10.0.0.3 0.0.0.0 area 1
network 172.17.3.0 0.0.0.255 area 1
network 172.17.13.0 0.0.0.3 area 1
R4:
router rip
version 2
passive-interface Ethernet0/0
network 192.168.0.0
network 192.168.4.0
network 192.168.24.0
no auto-summary
R7:
router ospf 1
redistribute connected metric 10 subnets //使用重发布直连发布业务网段
passive-interface Ethernet0/0
network 10.0.0.7 0.0.0.0 area 0
network 172.16.7.0 0.0.0.255 area 0
network 172.16.17.0 0.0.0.3 area 0
network 172.16.78.0 0.0.0.3 area 0
default-information originate always metric 2000 metric-type 1 //发布缺省路由
R8:
router ospf 1
passive-interface Ethernet0/0
network 10.0.0.8 0.0.0.0 area 0
network 172.16.78.0 0.0.0.3 area 0
network 172.18.8.0 0.0.0.255 area 2
network 172.18.28.0 0.0.0.3 area 2
查看OSPF的邻居
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.0.0.7 0 FULL/ - 00:00:29 172.16.17.2 Serial1/3
10.0.0.3 0 FULL/ - 00:00:31 172.17.13.2 Serial1/0
R2#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.0.0.8 0 FULL/ - 00:00:30 172.18.28.2 Serial1/3
R3#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.0.0.1 0 FULL/ - 00:00:30 172.17.13.1 Serial1/0
R8#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.0.0.7 0 FULL/ - 00:00:33 172.16.78.1 Serial1/1
10.0.0.2 0 FULL/ - 00:00:36 172.18.28.1 Serial1/0
R7#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.0.0.8 0 FULL/ - 00:00:30 172.16.78.2 Serial1/1
10.0.0.1 0 FULL/ - 00:00:39 172.16.17.1 Serial1/0
查看全局路由表
R3#show ip route
192.168.24.0/30 is subnetted, 1 subnets
O E1 192.168.24.0 [110/1400] via 172.17.13.1, 00:30:34, Serial1/0
172.17.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.17.13.0/30 is directly connected, Serial1/0
O 172.17.1.0/24 [110/110] via 172.17.13.1, 00:30:44, Serial1/0
C 172.17.3.0/24 is directly connected, Ethernet0/0
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
O E2 172.16.170.0/24 [110/10] via 172.17.13.1, 00:30:34, Serial1/0
O IA 172.16.17.0/30 [110/200] via 172.17.13.1, 00:30:44, Serial1/0
O IA 172.16.7.0/24 [110/210] via 172.17.13.1, 00:30:44, Serial1/0
O IA 172.16.78.0/30 [110/300] via 172.17.13.1, 00:30:44, Serial1/0
172.18.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.18.28.0/30 [110/400] via 172.17.13.1, 00:30:44, Serial1/0
O IA 172.18.8.0/24 [110/310] via 172.17.13.1, 00:30:45, Serial1/0
O IA 172.18.2.0/24 [110/410] via 172.17.13.1, 00:30:35, Serial1/0
O E1 192.168.4.0/24 [110/1400] via 172.17.13.1, 00:30:35, Serial1/0
10.0.0.0/32 is subnetted, 5 subnets
O IA 10.0.0.8 [110/301] via 172.17.13.1, 00:30:45, Serial1/0
O IA 10.0.0.2 [110/401] via 172.17.13.1, 00:30:35, Serial1/0
C 10.0.0.3 is directly connected, Loopback0
O IA 10.0.0.1 [110/101] via 172.17.13.1, 00:30:45, Serial1/0
O IA 10.0.0.7 [110/201] via 172.17.13.1, 00:30:45, Serial1/0
192.168.0.0/32 is subnetted, 1 subnets
O E1 192.168.0.4 [110/1400] via 172.17.13.1, 00:30:35, Serial1/0
O*E1 0.0.0.0/0 [110/2200] via 172.17.13.1, 00:30:35, Serial1/0
Ospf LSA分析
Ospf LSA 3 传播及计算分析
通过查看LSA熟悉172.17.3.1/24 这条路由是怎么样从R3传播到R4的,并理解LSA信息的内容,请跟踪172.17.3.1/24 这条路由的LSA信息进行分析
1) R3发起LSA1
R3# show ip ospf database router self-originate
OSPF Router with ID (10.0.0.3) (Process ID 1)
Router Link States (Area 1)
LS age: 1620
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 10.0.0.3
Advertising Router: 10.0.0.3
LS Seq Number: 80000006
Checksum: 0xFDA6
Length: 72
Number of Links: 4
Link connected to: a Stub Network
(Link ID) Network/subnet number: 172.17.3.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 10
2) R3在AREA1 LSA1泛洪
R1#show ip ospf database router adv-router 10.0.0.3
Link connected to: a Stub Network
(Link ID) Network/subnet number: 172.17.3.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 10
R1加上自己的链路开销,进行计算后到达172.17.3.0网段的开销是110
3) R1将计算好的路由以LSA3形式在Area 0 区域泛洪,
R1#show ip ospf database summary self-originate
LS age: 1465
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 172.17.3.0 (summary Network Number)
Advertising Router: 10.0.0.1
LS Seq Number: 80000006
Checksum: 0xBC41
Length: 28
Network Mask: /24
TOS: 0 Metric: 110
4) R8收到该LSA之后,重新计算,加上自己到达R1的开销200,再以LSA3在Area2泛洪
R8# show ip ospf database summary self-originate
LS age: 1574
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 172.17.3.0 (summary Network Number)
Advertising Router: 10.0.0.8
LS Seq Number: 80000006
Checksum: 0x69C4
Length: 28
Network Mask: /24
TOS: 0 Metric: 310
5) R2收到该LSA后将OSPF1重发布到RIP,R4收到
show ip ospf database summary
Routing Bit Set on this LSA
LS age: 1683
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 172.17.3.0 (summary Network Number)
Advertising Router: 10.0.0.8
LS Seq Number: 80000006
Checksum: 0x69C4
Length: 28
Network Mask: /24
TOS: 0 Metric: 310
R2#show ip route
O IA 172.17.3.0/24 [110/410] via 172.18.28.2, 03:21:06, Serial1/3
//R2加了自己到R8的链路开销
R2# show ip rip database
172.17.3.0/24 redistributed
[5] via 10.0.0.8,
6) RIP定期更新:R2通过RIP定期更新将重发布到RIP路由传播至R4
R4#show ip rip database
172.17.3.0/24
[5] via 192.168.24.1, 00:00:21, Serial1/0
通过查看LSA熟悉192.168.4.0/24这条路由是怎么样从R4传播到R3的,并理解LSA信息的内容,请跟踪192.168.4.0/24这条路由的LSA信息进行分析(area 2 是普通区域)
1) R4通过RIP定期更新将192.168.4.0/24这条路由传播至R2,R2收到该更新后将其重发布至ospf
R2#show run | begin router ospf
redistribute rip metric 1000 metric-type 1 subnets
R2# show ip route
R 192.168.4.0/24 [120/1] via 192.168.24.2, 00:00:11, Serial1/0
R 192.168.0.4 [120/1] via 192.168.24.2, 00:00:11, Serial1/0
C 192.168.24.0 is directly connected, Serial1/0
R2# show ip ospf database
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
192.168.0.4 10.0.0.2 461 0x80000008 0x008147 0
192.168.4.0 10.0.0.2 461 0x80000008 0x007D4B 0
192.168.24.0 10.0.0.2 461 0x80000008 0x008E29 0
R2# show ip ospf database external
LS age: 526
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 192.168.4.0 (External Network Number )
Advertising Router: 10.0.0.2
LS Seq Number: 80000008
Checksum: 0x7D4B
Length: 36
Network Mask: /24
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 1000
Forward Address: 0.0.0.0
External Route Tag: 0
2) OSPF路由域内LSA5泛洪
R3将收到该泛洪
R3# show ip ospf database
Type-5 AS External Link States
192.168.4.0 10.0.0.2 748 0x80000008 0x007D4B 0
3) R2重新发起自己的LSA1(ASBR=1),并在Area2泛洪
R2#show ip ospf database router self-originate
LS age: 882
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 10.0.0.2
Advertising Router: 10.0.0.2
LS Seq Number: 8000000A
Checksum: 0x3546
Length: 72
AS Boundary Router
Number of Links: 4
4) 区域内外部路由计算
R8收到R2发来的aSbr置位的LSA1
R8#show ip ospf database router
Routing Bit Set on this LSA
LS age: 1201
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 10.0.0.2
Advertising Router: 10.0.0.2
LS Seq Number: 8000000A
Checksum: 0x3546
Length: 72
AS Boundary Router
Number of Links: 4
5) R8将ASBR=1的LSA1向A0发起LSA4,在A0区域泛洪
R8#show ip ospf database asbr-summary self-originate
Summary ASB Link States (Area 0)
LS age: 1332
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(AS Boundary Router)
Link State ID: 10.0.0.2 (AS Boundary Router address)
Advertising Router: 10.0.0.8
LS Seq Number: 80000009
Checksum: 0x367B
Length: 28
Network Mask: /0
TOS: 0 Metric: 100
//说明自己到ASBR的开销是100
6) R1收到该LSA重新计算再以LSA4在A1泛洪
R1#show ip ospf database asbr-summary self-originate
OSPF Router with ID (10.0.0.1) (Process ID 1)
Summary ASB Link States (Area 1)
LS age: 1654
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(AS Boundary Router)
Link State ID: 10.0.0.2 (AS Boundary Router address)
Advertising Router: 10.0.0.1
LS Seq Number: 80000009
Checksum: 0x37B8
Length: 28
Network Mask: /0
TOS: 0 Metric: 300
7) R3收到该LSA
R3# show ip ospf database asbr-summary
OSPF Router with ID (10.0.0.3) (Process ID 1)
Summary ASB Link States (Area 1)
Routing Bit Set on this LSA
LS age: 1728
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(AS Boundary Router)
Link State ID: 10.0.0.2 (AS Boundary Router address)
Advertising Router: 10.0.0.1
LS Seq Number: 80000009
Checksum: 0x37B8
Length: 28
Network Mask: /0
TOS: 0 Metric: 300
R3# show ip ospf database external
Routing Bit Set on this LSA
LS age: 1890
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 192.168.4.0 (External Network Number )
Advertising Router: 10.0.0.2
LS Seq Number: 80000009
Checksum: 0x7B4C
Length: 36
Network Mask: /24
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 1000
Forward Address: 0.0.0.0
External Route Tag: 0
8) R3计算自己到ABR的开销是100,所以到达ASBR的开销是400,再加上自己收到的LSA5计算可得到达192.168.4.0/24网段的开销是100+300+1000=1400
通过查看LSA熟悉192.168.4.0/24这条路由是怎么样从R4传播到R3的,并理解LSA信息的内容,请跟踪192.168.4.0/24这条路由的LSA信息进行分析(area 2 是NSSA区域)
3) R4通过RIP定期更新将192.168.4.0/24这条路由传播至R2,R2收到该更新后将其重发布至ospf
R2#show run | begin router ospf
redistribute rip metric 1000 metric-type 1 subnets
R2# show ip route
R 192.168.4.0/24 [120/1] via 192.168.24.2, 00:00:11, Serial1/0
R 192.168.0.4 [120/1] via 192.168.24.2, 00:00:11, Serial1/0
C 192.168.24.0 is directly connected, Serial1/0
R2# show ip ospf database
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
192.168.0.4 10.0.0.2 461 0x80000008 0x008147 0
192.168.4.0 10.0.0.2 461 0x80000008 0x007D4B 0
192.168.24.0 10.0.0.2 461 0x80000008 0x008E29 0
R2# show ip ospf database external
LS age: 526
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 192.168.4.0 (External Network Number )
Advertising Router: 10.0.0.2
LS Seq Number: 80000008
Checksum: 0x7D4B
Length: 36
Network Mask: /24
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 1000
Forward Address: 0.0.0.0
External Route Tag: 0
4) R2产生一条LSA7在AREA2区域泛洪,
R2#show ip ospf database nssa-external
OSPF Router with ID (10.0.0.2) (Process ID 1)
Type-7 AS External Link States (Area 2)
LS age: 132
Options: (No TOS-capability, Type 7/5 translation, DC)
LS Type: AS External Link
Link State ID: 192.168.4.0 (External Network Number )
Advertising Router: 10.0.0.2
LS Seq Number: 80000001
Checksum: 0x8138
Length: 36
Network Mask: /24
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 1000
Forward Address: 10.0.0.2
External Route Tag: 0
5) 由于这条LSA7的P-bit置位了,ABR(R8)路由器把这条NSSA外部LSA(LSA7)转换为一条AS外部LSA(LSA5),在ospf路由与泛洪,并携带转发地址
R8#show ip ospf da nssa-external
Routing Bit Set on this LSA
LS age: 1628
Options: (No TOS-capability, Type 7/5 translation, DC)
LS Type: AS External Link
Link State ID: 192.168.4.0 (External Network Number )
Advertising Router: 10.0.0.2
LS Seq Number: 80000003
Checksum: 0x7D3A
Length: 36
Network Mask: /24
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 1000
Forward Address: 10.0.0.2
External Route Tag: 0
R8#show ip ospf da external
S age: 1657
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 192.168.4.0 (External Network Number )
Advertising Router: 10.0.0.8
LS Seq Number: 80000003
Checksum: 0xEDCD
Length: 36
Network Mask: /24
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 1000
Forward Address: 10.0.0.2
External Route Tag: 0
6) 此时是R8告诉整个ospf路由域的路由器,可以从10.0.0.2这个地址到达192.168.4.0/24,且开销是1000,R3会收到这个LSA5的泛洪
7) R2将10.0.0.2这个地址在area 2 以LSA1泛洪
R8#show ip ospf database router adv-router 10.0.0.2
Link connected to: a Stub Network
(Link ID) Network/subnet number: 10.0.0.2
(Link Data) Network Mask: 255.255.255.255
Number of TOS metrics: 0
TOS 0 Metrics: 1
8) R8收到后加上自己到达10.0.0.2的开销以后再以LAS3在AREA0 区域泛洪,
R8#show ip ospf database summary self-originate
OSPF Router with ID (10.0.0.8) (Process ID 1)
Summary Net Link States (Area 0)
LS age: 838
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 10.0.0.2 (summary Network Number)
Advertising Router: 10.0.0.8
LS Seq Number: 80000001
Checksum: 0x5E5B
Length: 28
Network Mask: /32
TOS: 0 Metric: 101
9) R1收到R8发来的LSA3
R1# show ip ospf database summary adv-router 10.0.0.8
OSPF Router with ID (10.0.0.1) (Process ID 1)
Summary Net Link States (Area 0)
Routing Bit Set on this LSA
LS age: 951
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 10.0.0.2 (summary Network Number)
Advertising Router: 10.0.0.8
LS Seq Number: 80000001
Checksum: 0x5E5B
Length: 28
Network Mask: /32
TOS: 0 Metric: 101
10) R1 加上自己到达10.0.0.8的开销之后再以LSA3在区域1泛洪
R1# show ip ospf database summary self-originate
LS age: 1026
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 10.0.0.2 (summary Network Number)
Advertising Router: 10.0.0.1
LS Seq Number: 80000001
Checksum: 0x5F98
Length: 28
Network Mask: /32
TOS: 0 Metric: 301
11) R3收到该条LSA,加上自己到达始发者R1的开销100后计算得知,到达10.0.0.2(R2)开销是401,再加上自己之前收到的LSA5说明的从10.0.0.2这个转发地址到达192.168.4.0/24网段的开销是1000之后,可得到,R3到达该网段的开销是1000+401=1401
附:R3#show ip ospf database external
Routing Bit Set on this LSA
LS age: 1219
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 192.168.4.0 (External Network Number )
Advertising Router: 10.0.0.8
LS Seq Number: 80000001
Checksum: 0xF1CB
Length: 36
Network Mask: /24
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 1000
Forward Address: 10.0.0.2
External Route Tag: 0
OSPF标准区域缺省路由发布,传播及计算分析
1) OSPF标准区域缺省路由发布
R7#show run | begin router ospf
default-information originate always metric 2000 metric-type 1
R7#show ip ospf database
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 10.0.0.7 1036 0x8000000C 0x007AC5 1
R7#show ip ospf database external self-originate
OSPF Router with ID (10.0.0.7) (Process ID 1)
Type-5 AS External Link States
LS age: 1104
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 0.0.0.0 (External Network Number )
Advertising Router: 10.0.0.7
LS Seq Number: 8000000C
Checksum: 0x7AC5
Length: 36
Network Mask: /0
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 2000
Forward Address: 0.0.0.0
External Route Tag: 1
R7#show ip ospf database router self-originate
LS age: 1137
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 10.0.0.7
Advertising Router: 10.0.0.7
LS Seq Number: 8000000E
Checksum: 0xEB8C
Length: 96
AS Boundary Router
Number of Links: 6
R1#show ip ospf database asbr-summary self-originate
OSPF Router with ID (10.0.0.1) (Process ID 1)
Summary ASB Link States (Area 1)
LS age: 989
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(AS Boundary Router)
Link State ID: 10.0.0.7 (AS Boundary Router address)
Advertising Router: 10.0.0.1
LS Seq Number: 8000000C
Checksum: 0x2888
Length: 28
Network Mask: /0
TOS: 0 Metric: 100
2) 缺省路由传播和计算
其传播行为与LSA5完全相同
其计算方法与LSA5完全相同
R8# show ip route
O*E1 0.0.0.0/0 [110/2100] via 172.16.78.1, 01:07:56, Serial1/1
R3#show ip route
O*E1 0.0.0.0/0 [110/2200] via 172.17.13.1, 01:08:13, Serial1/0
Ospf路由汇总配置与分析
Ospf区域路由汇总
1) 汇总前LSA信息
R1#show ip ospf database self-originate
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.0.0.3 10.0.0.1 724 0x8000000D 0x00664D
172.17.1.0 10.0.0.1 724 0x8000000D 0x00D884
172.17.3.0 10.0.0.1 724 0x8000000D 0x00AE48
172.17.13.0 10.0.0.1 724 0x8000000D 0x00C930
2) 区域间路由汇总配置
R1(config)#router ospf 1
R1(config-router)#area 1 range 172.17.0.0 255.255.0.0
查看汇总情况
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.0.0.3 10.0.0.1 999 0x8000000D 0x00664D
172.17.0.0 10.0.0.1 87 0x80000001 0x00FB6E
Ospf外部路由汇总
1) 汇总前LSA信息
R2#show ip route
R 192.168.4.0/24 [120/1] via 192.168.24.2, 00:00:01, Serial1/0
R 192.168.0.4 [120/1] via 192.168.24.2, 00:00:01, Serial1/0
C 192.168.24.0 is directly connected, Serial1/0
R2# show ip ospf database self-originate
OSPF Router with ID (10.0.0.2) (Process ID 1)
Type-7 AS External Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Tag
192.168.0.4 10.0.0.2 354 0x80000004 0x007F37 0
192.168.4.0 10.0.0.2 354 0x80000004 0x007B3B 0
192.168.24.0 10.0.0.2 354 0x80000004 0x008C19 0
2) 外部路由汇总配置
汇总路由总结:
在由LSA7引入外部路由的时候可以在NSSA区域的ASBR上做汇总,或者在NSSA区域的ABR上做汇总
在由LSA5引入外部路由的时候在ASBR上做汇总,其他路由器将收到汇总后的LSA5
Summary-address汇总路由存在条件:
有外部路由的细化路由
做3替5时应注意:
在本实验的拓扑图中的Area2区域与RIP区域的ip地址必须是连续的
Ospf特殊区域配置与分析
1) Stub 区域
配置成Stub区域之前
R3#show ip ospf database
OSPF Router with ID (10.0.0.3) (Process ID 1)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
10.0.0.1 10.0.0.1 85 0x80000002 0x00C406 3
10.0.0.3 10.0.0.3 85 0x80000002 0x0006A2 4
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.0.0.1 10.0.0.1 91 0x80000001 0x00A67F
10.0.0.2 10.0.0.1 72 0x80000001 0x005F98
10.0.0.7 10.0.0.1 82 0x80000001 0x005665
10.0.0.8 10.0.0.1 72 0x80000001 0x00381E
172.16.7.0 10.0.0.1 82 0x80000001 0x00A659
172.16.17.0 10.0.0.1 82 0x80000001 0x00C141
172.16.78.0 10.0.0.1 82 0x80000001 0x000C55
172.18.2.0 10.0.0.1 72 0x80000001 0x009C9D
172.18.8.0 10.0.0.1 72 0x80000001 0x006F29
172.18.28.0 10.0.0.1 72 0x80000001 0x000726
Summary ASB Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.0.0.2 10.0.0.1 72 0x80000001 0x0047B0
10.0.0.7 10.0.0.1 92 0x80000001 0x003E7D
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 10.0.0.7 108 0x80000001 0x0090BA 1
172.16.170.0 10.0.0.7 108 0x80000001 0x00240E 0
192.168.0.4 10.0.0.2 110 0x80000001 0x008F40 0
192.168.4.0 10.0.0.2 110 0x80000001 0x008B44 0
192.168.24.0 10.0.0.2 110 0x80000001 0x009C22 0
R3# show ip route
192.168.24.0/30 is subnetted, 1 subnets
O E1 192.168.24.0 [110/1400] via 172.17.13.1, 00:01:40, Serial1/0
172.17.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.17.13.0/30 is directly connected, Serial1/0
O 172.17.1.0/24 [110/110] via 172.17.13.1, 00:01:50, Serial1/0
C 172.17.3.0/24 is directly connected, Ethernet0/0
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
O E2 172.16.170.0/24 [110/10] via 172.17.13.1, 00:01:40, Serial1/0
O IA 172.16.17.0/30 [110/200] via 172.17.13.1, 00:01:50, Serial1/0
O IA 172.16.7.0/24 [110/210] via 172.17.13.1, 00:01:50, Serial1/0
O IA 172.16.78.0/30 [110/300] via 172.17.13.1, 00:01:50, Serial1/0
172.18.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.18.28.0/30 [110/400] via 172.17.13.1, 00:01:40, Serial1/0
O IA 172.18.8.0/24 [110/310] via 172.17.13.1, 00:01:42, Serial1/0
O IA 172.18.2.0/24 [110/410] via 172.17.13.1, 00:01:42, Serial1/0
O E1 192.168.4.0/24 [110/1400] via 172.17.13.1, 00:01:42, Serial1/0
10.0.0.0/32 is subnetted, 5 subnets
O IA 10.0.0.8 [110/301] via 172.17.13.1, 00:01:42, Serial1/0
O IA 10.0.0.2 [110/401] via 172.17.13.1, 00:01:42, Serial1/0
C 10.0.0.3 is directly connected, Loopback0
O IA 10.0.0.1 [110/101] via 172.17.13.1, 00:01:52, Serial1/0
O IA 10.0.0.7 [110/201] via 172.17.13.1, 00:01:52, Serial1/0
192.168.0.0/32 is subnetted, 1 subnets
O E1 192.168.0.4 [110/1400] via 172.17.13.1, 00:01:42, Serial1/0
O*E1 0.0.0.0/0 [110/2200] via 172.17.13.1, 00:01:42, Serial1/0
2) 配置stub区域
R3(config)#router os 1
R3(config-router)#area 1 stub
R1(config)#router os 1
R1(config-router)#area 1 stub
3) 比较全局路由表和ospf数据库的变化
R3#show ip ospf database
OSPF Router with ID (10.0.0.3) (Process ID 1)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
10.0.0.1 10.0.0.1 37 0x80000004 0x00DEEB 3
10.0.0.3 10.0.0.3 37 0x80000004 0x002088 4
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
0.0.0.0 10.0.0.1 42 0x80000001 0x0051E1
10.0.0.1 10.0.0.1 42 0x80000002 0x00C264
10.0.0.2 10.0.0.1 42 0x80000002 0x007B7D
10.0.0.7 10.0.0.1 42 0x80000002 0x00724A
10.0.0.8 10.0.0.1 42 0x80000002 0x005403
172.16.7.0 10.0.0.1 42 0x80000002 0x00C23E
172.16.17.0 10.0.0.1 42 0x80000002 0x00DD26
172.16.78.0 10.0.0.1 42 0x80000002 0x00283A
172.18.2.0 10.0.0.1 42 0x80000002 0x00B882
172.18.8.0 10.0.0.1 42 0x80000002 0x008B0E
172.18.28.0 10.0.0.1 42 0x80000002 0x00230B
通过比较可以看出,数据库明显变小了,只有LSA1和LSA3.是因为stub区域过滤掉了LSA5和LSA4类,但同时为了能达到去往其他区域的目的,有一条R1自动下发的缺省LSA3
R3#show ip route
172.17.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.17.13.0/30 is directly connected, Serial1/0
O 172.17.1.0/24 [110/110] via 172.17.13.1, 00:04:11, Serial1/0
C 172.17.3.0/24 is directly connected, Ethernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.16.17.0/30 [110/200] via 172.17.13.1, 00:04:11, Serial1/0
O IA 172.16.7.0/24 [110/210] via 172.17.13.1, 00:04:11, Serial1/0
O IA 172.16.78.0/30 [110/300] via 172.17.13.1, 00:04:11, Serial1/0
172.18.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.18.28.0/30 [110/400] via 172.17.13.1, 00:04:11, Serial1/0
O IA 172.18.8.0/24 [110/310] via 172.17.13.1, 00:04:11, Serial1/0
O IA 172.18.2.0/24 [110/410] via 172.17.13.1, 00:04:11, Serial1/0
10.0.0.0/32 is subnetted, 5 subnets
O IA 10.0.0.8 [110/301] via 172.17.13.1, 00:04:12, Serial1/0
O IA 10.0.0.2 [110/401] via 172.17.13.1, 00:04:12, Serial1/0
C 10.0.0.3 is directly connected, Loopback0
O IA 10.0.0.1 [110/101] via 172.17.13.1, 00:04:12, Serial1/0
O IA 10.0.0.7 [110/201] via 172.17.13.1, 00:04:12, Serial1/0
O*IA 0.0.0.0/0 [110/101] via 172.17.13.1, 00:04:12, Serial1/0
通过比较可以看出,所有外部路由都被过滤掉了,且多了一条缺省路由下一跳指向R1
2) 完全stub区域
①配置完全stub区域
R3(config)#router ospf 1
R3(config-router)#area 1 stub
R1(config)#router ospf 1
R1(config-router)#area 1 stub no-summary// no-summary 只需在该区域的ABR上配置
2)比较全局路由表和ospf数据库的变化
R3#show ip ospf database
OSPF Router with ID (10.0.0.3) (Process ID 1)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
10.0.0.1 10.0.0.1 518 0x80000004 0x00DEEB 3
10.0.0.3 10.0.0.3 518 0x80000004 0x002088 4
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
0.0.0.0 10.0.0.1 98 0x80000002 0x004FE2
通过比较可以看出,数据库中只有LSA1和LSA3,除了过滤了LSA4和LSA5之外,同时过滤了LSA3,但是为了能够与其他区域共同,ABR自动下发了一条LSA3缺省LSA
R3#show ip route
172.17.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.17.13.0/30 is directly connected, Serial1/0
O 172.17.1.0/24 [110/110] via 172.17.13.1, 00:11:57, Serial1/0
C 172.17.3.0/24 is directly connected, Ethernet0/0
10.0.0.0/32 is subnetted, 1 subnets
C 10.0.0.3 is directly connected, Loopback0
O*IA 0.0.0.0/0 [110/101] via 172.17.13.1, 00:11:57, Serial1/0
通过比较可以看出,路由条目大大减少了
3) NSSA区域
① 配置NSSA区域前的OSPF LSDB和全局路由表
R2#show ip ospf database
OSPF Router with ID (10.0.0.2) (Process ID 1)
Router Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Link count
10.0.0.2 10.0.0.2 1165 0x80000004 0x004140 4
10.0.0.8 10.0.0.8 1177 0x80000003 0x007E15 3
Summary Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
10.0.0.1 10.0.0.8 1177 0x80000002 0x005203
10.0.0.3 10.0.0.8 931 0x80000002 0x0029C5
10.0.0.7 10.0.0.8 1177 0x80000002 0x002A89
10.0.0.8 10.0.0.8 1177 0x80000002 0x0034E2
172.16.7.0 10.0.0.8 1177 0x80000002 0x007A7D
172.16.17.0 10.0.0.8 1177 0x80000002 0x008115
172.16.78.0 10.0.0.8 1177 0x80000002 0x00F3C9
172.17.1.0 10.0.0.8 1177 0x80000002 0x009CFB
172.17.3.0 10.0.0.8 931 0x80000002 0x0071C0
172.17.13.0 10.0.0.8 1177 0x80000002 0x008CA8
Summary ASB Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
10.0.0.7 10.0.0.8 1177 0x80000002 0x0012A1
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 10.0.0.7 1168 0x80000002 0x008EBB 1
172.16.170.0 10.0.0.7 1168 0x80000002 0x00220F 0
192.168.0.4 10.0.0.2 1166 0x80000002 0x008D41 0
192.168.4.0 10.0.0.2 1166 0x80000002 0x008945 0
192.168.24.0 10.0.0.2 1166 0x80000002 0x009A23 0
这个数据库中有LSA1 LSA3 LSA4 LSA5
R2#show ip route
192.168.24.0/30 is subnetted, 1 subnets
C 192.168.24.0 is directly connected, Serial1/0
172.17.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.17.13.0/30 [110/400] via 172.18.28.2, 00:54:06, Serial1/3
O IA 172.17.1.0/24 [110/310] via 172.18.28.2, 00:54:06, Serial1/3
O IA 172.17.3.0/24 [110/410] via 172.18.28.2, 00:49:39, Serial1/3
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
O E2 172.16.170.0/24 [110/10] via 172.18.28.2, 00:49:34, Serial1/3
O IA 172.16.17.0/30 [110/300] via 172.18.28.2, 00:54:06, Serial1/3
O IA 172.16.7.0/24 [110/210] via 172.18.28.2, 00:54:06, Serial1/3
O IA 172.16.78.0/30 [110/200] via 172.18.28.2, 00:54:06, Serial1/3
172.18.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.18.28.0/30 is directly connected, Serial1/3
O 172.18.8.0/24 [110/110] via 172.18.28.2, 00:54:07, Serial1/3
C 172.18.2.0/24 is directly connected, Ethernet0/0
R 192.168.4.0/24 [120/1] via 192.168.24.2, 00:00:10, Serial1/0
10.0.0.0/32 is subnetted, 5 subnets
O IA 10.0.0.8 [110/101] via 172.18.28.2, 00:54:07, Serial1/3
C 10.0.0.2 is directly connected, Loopback0
O IA 10.0.0.3 [110/401] via 172.18.28.2, 00:49:40, Serial1/3
O IA 10.0.0.1 [110/301] via 172.18.28.2, 00:54:07, Serial1/3
O IA 10.0.0.7 [110/201] via 172.18.28.2, 00:54:07, Serial1/3
192.168.0.0/32 is subnetted, 1 subnets
R 192.168.0.4 [120/1] via 192.168.24.2, 00:00:10, Serial1/0
O*E1 0.0.0.0/0 [110/2200] via 172.18.28.2, 00:49:35, Serial1/3
这个路由表中有区域间路由和外部路由
②配置NSSA区域
R2(config)#router ospf1
R2(config-router)#area 2 NSSA
R8(config)#router ospf 1
R8(config-router)#area 2 NSSA
③ 比较全局路由表和ospf数据库的变化
R2#show ip ospf database
OSPF Router with ID (10.0.0.2) (Process ID 1)
Router Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Link count
10.0.0.2 10.0.0.2 138 0x80000006 0x00E296 4
10.0.0.8 10.0.0.8 138 0x80000005 0x002663 3
Summary Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
10.0.0.1 10.0.0.8 146 0x80000003 0x00F558
10.0.0.3 10.0.0.8 146 0x80000003 0x00CC1B
10.0.0.7 10.0.0.8 146 0x80000003 0x00CDDE
10.0.0.8 10.0.0.8 146 0x80000003 0x00D738
172.16.7.0 10.0.0.8 146 0x80000003 0x001ED2
172.16.17.0 10.0.0.8 146 0x80000003 0x00256A
172.16.78.0 10.0.0.8 146 0x80000003 0x00971F
172.17.1.0 10.0.0.8 146 0x80000003 0x004051
172.17.3.0 10.0.0.8 146 0x80000003 0x001516
172.17.13.0 10.0.0.8 146 0x80000003 0x0030FD
Type-7 AS External Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Tag
192.168.0.4 10.0.0.2 168 0x80000001 0x008534 0
192.168.4.0 10.0.0.2 169 0x80000001 0x008138 0
192.168.24.0 10.0.0.2 169 0x80000001 0x009216 0
经比较可以看出,ospf数据库中没有了LSA5但是多了LSA7,说明NSSA区域过滤掉了非本区域引进的外部路由即过滤掉了五类LSA
R2# show ip route
192.168.24.0/30 is subnetted, 1 subnets
C 192.168.24.0 is directly connected, Serial1/0
172.17.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.17.13.0/30 [110/400] via 172.18.28.2, 00:34:36, Serial1/3
O IA 172.17.1.0/24 [110/310] via 172.18.28.2, 00:34:36, Serial1/3
O IA 172.17.3.0/24 [110/410] via 172.18.28.2, 00:34:36, Serial1/3
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.16.17.0/30 [110/300] via 172.18.28.2, 00:34:37, Serial1/3
O IA 172.16.7.0/24 [110/210] via 172.18.28.2, 00:34:37, Serial1/3
O IA 172.16.78.0/30 [110/200] via 172.18.28.2, 00:34:36, Serial1/3
172.18.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.18.28.0/30 is directly connected, Serial1/3
O 172.18.8.0/24 [110/110] via 172.18.28.2, 00:34:37, Serial1/3
C 172.18.2.0/24 is directly connected, Ethernet0/0
R 192.168.4.0/24 [120/1] via 192.168.24.2, 00:00:19, Serial1/0
10.0.0.0/32 is subnetted, 5 subnets
O IA 10.0.0.8 [110/101] via 172.18.28.2, 00:34:37, Serial1/3
C 10.0.0.2 is directly connected, Loopback0
O IA 10.0.0.3 [110/401] via 172.18.28.2, 00:34:37, Serial1/3
O IA 10.0.0.1 [110/301] via 172.18.28.2, 00:34:37, Serial1/3
O IA 10.0.0.7 [110/201] via 172.18.28.2, 00:34:37, Serial1/3
192.168.0.0/32 is subnetted, 1 subnets
R 192.168.0.4 [120/1] via 192.168.24.2, 00:00:19, Serial1/0
通过比较可以看出,没有了OE1和OE2
④NSSA区域的ABR LSA7转LAS5
R8#show ip ospf database
OSPF Router with ID (10.0.0.8) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
10.0.0.1 10.0.0.1 1736 0x80000005 0x000179 3
10.0.0.7 10.0.0.7 1769 0x80000005 0x00FD83 6
10.0.0.8 10.0.0.8 248 0x80000006 0x00B333 3
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.0.0.2 10.0.0.8 248 0x80000002 0x005C5C
10.0.0.3 10.0.0.1 1486 0x80000003 0x007A43
172.17.1.0 10.0.0.1 1736 0x80000003 0x00EC7A
172.17.3.0 10.0.0.1 1486 0x80000003 0x00C23E
172.17.13.0 10.0.0.1 1736 0x80000003 0x00DD26
172.18.2.0 10.0.0.8 248 0x80000002 0x009961
172.18.8.0 10.0.0.8 1772 0x80000003 0x0069EE
172.18.28.0 10.0.0.8 1772 0x80000003 0x0002EA
Router Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Link count
10.0.0.2 10.0.0.2 435 0x80000007 0x00E097 4
10.0.0.8 10.0.0.8 248 0x80000006 0x002464 3
Summary Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
10.0.0.1 10.0.0.8 492 0x80000004 0x00F359
10.0.0.3 10.0.0.8 492 0x80000004 0x00CA1C
10.0.0.7 10.0.0.8 492 0x80000004 0x00CBDF
10.0.0.8 10.0.0.8 492 0x80000004 0x00D539
172.16.7.0 10.0.0.8 492 0x80000004 0x001CD3
172.16.17.0 10.0.0.8 492 0x80000004 0x00236B
172.16.78.0 10.0.0.8 492 0x80000004 0x009520
172.17.1.0 10.0.0.8 492 0x80000004 0x003E52
172.17.3.0 10.0.0.8 492 0x80000004 0x001317
172.17.13.0 10.0.0.8 492 0x80000004 0x002EFE
Type-7 AS External Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Tag
192.168.0.4 10.0.0.2 436 0x80000002 0x008335 0
192.168.4.0 10.0.0.2 436 0x80000002 0x007F39 0
192.168.24.0 10.0.0.2 436 0x80000002 0x009017 0
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 10.0.0.7 1770 0x80000003 0x008CBC 1
172.16.170.0 10.0.0.7 1770 0x80000003 0x002010 0
192.168.0.4 10.0.0.8 248 0x80000002 0x00F3C8 0
192.168.4.0 10.0.0.8 248 0x80000002 0x00EFCC 0
192.168.24.0 10.0.0.8 248 0x80000002 0x0001AA 0
可以看出,R8上面既有 LSA7也有LSA5,但是,LSA7中的LSA同样在LSA5中也有,说明R8作为NSSA的ABR做了LSA7转LSA5
R8# show ip route
O N1 192.168.24.0 [110/1101] via 172.18.28.1, 00:42:00, Serial1/0
O N1 192.168.4.0/24 [110/1101] via 172.18.28.1, 00:42:00, Serial1/0
O N1 192.168.0.4 [110/1101] via 172.18.28.1, 00:42:00, Serial1/0
R8#show ip ospf database external
LS age: 671
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 192.168.0.4 (External Network Number )
Advertising Router: 10.0.0.8
LS Seq Number: 80000002
Checksum: 0xF3C8
Length: 36
Network Mask: /32
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 1000
Forward Address: 10.0.0.2
External Route Tag: 0
LS age: 672
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 192.168.4.0 (External Network Number )
Advertising Router: 10.0.0.8
LS Seq Number: 80000002
Checksum: 0xEFCC
Length: 36
Network Mask: /24
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 1000
Forward Address: 10.0.0.2
External Route Tag: 0
LS age: 672
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 192.168.24.0 (External Network Number )
Advertising Router: 10.0.0.8
LS Seq Number: 80000002
Checksum: 0x1AA
Length: 36
Network Mask: /30
Metric Type: 1 (Comparable directly to link state metric)
TOS: 0
Metric: 1000
Forward Address: 10.0.0.2
External Route Tag: 0
这些LSA5都是带有转发地址的,说明是进行了LSA7转LSA5的
R8#show ip ospf database router
LS age: 845
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 10.0.0.8
Advertising Router: 10.0.0.8
LS Seq Number: 80000006
Checksum: 0xB333
Length: 60
Area Border Router
AS Boundary Router
Number of Links: 3
它自己发起的LSA1中描述自己是 ABR 同时又是ASBR
LSA7转LSA5之后,LSA4由谁发起?
答:由R1发起,因为R8自己认为是ASBR,所以就会发一个ASBR=1的一类LSA,R1作为另外一台ABR,它收到后便产生LSA4
R1#show ip ospf database asbr-summary
LS age: 20
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(AS Boundary Router)
Link State ID: 10.0.0.8 (AS Boundary Router address)
Advertising Router: 10.0.0.1
LS Seq Number: 80000001
Checksum: 0x2036
Length: 28
Network Mask: /0
TOS: 0 Metric: 200
R3#show ip ospf database asbr-summary
Routing Bit Set on this LSA
LS age: 184
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(AS Boundary Router)
Link State ID: 10.0.0.8 (AS Boundary Router address)
Advertising Router: 10.0.0.1
LS Seq Number: 80000001
Checksum: 0x2036
Length: 28
Network Mask: /0
TOS: 0 Metric: 200
R3收到R1发来的LSA4,说明ASBR的位置(但是因为此ASBR非真正的ASBR,所以我们不用这个来计算)
R3#show ip route
O E1 192.168.0.4 [110/1401] via 172.17.13.1, 00:10:14, Serial1/0
O E1 192.168.4.0/24 [110/1401] via 172.17.13.1, 00:10:14, Serial1/0
⑤ NSSA 区域缺省路由发布
R8(config)#router os 1
R8(config-router)#area 2 nssa default-information-originate
R2# show ip os database
Type-7 AS External Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 10.0.0.8 54 0x80000001 0x005072 0
192.168.0.4 10.0.0.2 70 0x80000003 0x008136 0
192.168.4.0 10.0.0.2 70 0x80000003 0x007D3A 0
192.168.24.0 10.0.0.2 70 0x80000003 0x008E18 0
多了一条缺省LSA7
R2#show ip route
O*N2 0.0.0.0/0 [110/1] via 172.18.28.2, 00:00:22, Serial1/3
4) 完全NSSA区域
① 配置完全NSSA区域
R2(config)#router ospf 1
R2(config-router)#area 2 nssa
R8(config)#router os 1
R8(config-router)#area 2 nssa no-summary
② 比较全局路由表和ospf数据库的变化
R2#show ip ospf database
OSPF Router with ID (10.0.0.2) (Process ID 1)
Router Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Link count
10.0.0.2 10.0.0.2 541 0x8000000A 0x00DA9A 4
10.0.0.8 10.0.0.8 546 0x8000000A 0x001C68 3
Summary Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
0.0.0.0 10.0.0.8 555 0x80000001 0x00AE75
Type-7 AS External Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Tag
192.168.0.4 10.0.0.2 838 0x80000003 0x008136 0
192.168.4.0 10.0.0.2 838 0x80000003 0x007D3A 0
192.168.24.0 10.0.0.2 838 0x80000003 0x008E18 0
经比较可以看出,完全NSSA区域过滤掉了三类跟五类,但是同时自动产生了三类缺省LSA
R2# show ip route
192.168.24.0/30 is subnetted, 1 subnets
C 192.168.24.0 is directly connected, Serial1/0
172.18.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.18.28.0/30 is directly connected, Serial1/3
O 172.18.8.0/24 [110/110] via 172.18.28.2, 00:10:06, Serial1/3
C 172.18.2.0/24 is directly connected, Ethernet0/0
R 192.168.4.0/24 [120/1] via 192.168.24.2, 00:00:07, Serial1/0
10.0.0.0/32 is subnetted, 1 subnets
C 10.0.0.2 is directly connected, Loopback0
192.168.0.0/32 is subnetted, 1 subnets
R 192.168.0.4 [120/1] via 192.168.24.2, 00:00:07, Serial1/0
O*IA 0.0.0.0/0 [110/101] via 172.18.28.2, 00:10:06, Serial1/3
通过比较,全局路由表中只有区域间缺省路由 下一跳R8的直连出口
R8#show ip ospf database
Type-7 AS External Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Tag
192.168.0.4 10.0.0.2 1040 0x80000003 0x008136 0
192.168.4.0 10.0.0.2 1040 0x80000003 0x007D3A 0
192.168.24.0 10.0.0.2 1040 0x80000003 0x008E18 0
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 10.0.0.7 356 0x80000005 0x0088BE 1
172.16.170.0 10.0.0.7 356 0x80000005 0x001C12 0
192.168.0.4 10.0.0.8 734 0x80000001 0x00F5C7 0
192.168.4.0 10.0.0.8 734 0x80000001 0x00F1CB 0
192.168.24.0 10.0.0.8 735 0x80000001 0x0003A9 0
既有LSA5 也有LSA7
R8# show ip route
O N1 192.168.0.4 [110/1101] via 172.18.28.1, 00:13:32, Serial1/0
O N1 192.168.24.0 [110/1101] via 172.18.28.1, 00:13:32, Serial1/0
R8上显示的192.168.0.0/16是ON1
R7#show ip route
O E1 192.168.24.0 [110/1201] via 172.16.78.2, 00:48:57, Serial1/1
O E1 192.168.0.4 [110/1201] via 172.16.78.2, 00:48:57, Serial1/1
R7上显示192.168.0.0/16网段的路由是一OE1形式的说明LSA7转LSA5成功
5) 外部路由过滤
在NSSA区域ABR 上,利用LSA7转LSA5时可以做外部路由汇总,使用外部路由汇总过滤,来过滤外部路由,并使用 Area range 区域汇总路由的LSA3来代替LSA7转LSA5(即使用LSA3代替LSA5),来解决区域间外部路由的可达性问题
R2(config)#router os 1
R2(config-router)#net 192.168.24.0 0.0.0.3 a 2 //area range 汇总的触发条件
R2(config-router)#pa s1/0
R7#show ip route
O IA 192.168.24.0 [110/264] via 172.16.78.2, 00:00:27, Serial1/1
R8# show ip route
O 192.168.24.0 [110/164] via 172.18.28.1, 00:00:44, Serial1/0
R8(config)#router os 1
R8(config-router)#area 2 range 192.168.0.0 255.255.0.0 //使用LSA3代替LSA5
R8(config-router)#summary-address 0.0.0.0 0.0.0.0 not-advertise//过滤掉所有外部路由
R7#show ip route
O IA 192.168.0.0/16 [110/264] via 172.16.78.2, 00:02:05, Serial1/1
这个时候,如果Area2区域的ip地址也在192.168.0.0/16范围就会减少更多路由条目
6)ospf V-LINK
① 没有AREA0连接的区域
R2和 R4的RIP改成OSPF AREA3
R4#show ip route
192.168.24.0/30 is subnetted, 1 subnets
C 192.168.24.0 is directly connected, Serial1/0
C 192.168.4.0/24 is directly connected, Ethernet0/0
10.0.0.0/32 is subnetted, 1 subnets
C 10.0.0.4 is directly connected, Loopback0
R2#show ip route
O 192.168.4.0/24 [110/74] via 192.168.24.2, 00:00:49, Serial1/0
O 10.0.0.4 [110/65] via 192.168.24.2, 00:00:49, Serial1/0
R8#show ip route
172.17.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.17.13.0/30 [110/300] via 172.16.78.1, 00:07:10, Serial1/1
O IA 172.17.1.0/24 [110/210] via 172.16.78.1, 00:07:10, Serial1/1
O IA 172.17.3.0/24 [110/310] via 172.16.78.1, 00:07:10, Serial1/1
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
O E2 172.16.170.0/24 [110/10] via 172.16.78.1, 00:07:10, Serial1/1
O 172.16.17.0/30 [110/200] via 172.16.78.1, 00:07:20, Serial1/1
O 172.16.7.0/24 [110/110] via 172.16.78.1, 00:07:20, Serial1/1
C 172.16.78.0/30 is directly connected, Serial1/1
172.18.0.0/16 is variably subnetted, 3 subnets, 2 masks
C 172.18.28.0/30 is directly connected, Serial1/0
C 172.18.8.0/24 is directly connected, Ethernet0/0
O 172.18.2.0/24 [110/110] via 172.18.28.1, 00:07:10, Serial1/0
10.0.0.0/32 is subnetted, 5 subnets
C 10.0.0.8 is directly connected, Loopback0
O 10.0.0.2 [110/101] via 172.18.28.1, 00:07:11, Serial1/0
O IA 10.0.0.3 [110/301] via 172.16.78.1, 00:07:11, Serial1/1
O 10.0.0.1 [110/201] via 172.16.78.1, 00:07:21, Serial1/1
O 10.0.0.7 [110/101] via 172.16.78.1, 00:07:21, Serial1/1
O*E1 0.0.0.0/0 [110/2100] via 172.16.78.1, 00:07:11, Serial1/1
可以看出R8上没有区域3的路由
下面做V-LINK
R2(config)#router os 1
R2(config-router)#area 2 virtual-link 10.0.0.8
R8(config)#router os 1
R8(config-router)#area 2 virtual-link 10.0.0.2 //对端router-id
R2#show ip ospf virtual-links
Virtual Link OSPF_VL0 to router 10.0.0.8 is up
Run as demand circuit
DoNotAge LSA allowed.
Transit area 2, via interface Serial1/3, Cost of using 100 //穿越area2 通过s1/3 开销100
这时候我们再看看R8上是否学习到了192.168.0.0/16的路由
R8#show ip route
O IA 192.168.24.0 [110/164] via 172.18.28.1, 00:02:40, Serial1/0
O IA 192.168.4.0/24 [110/174] via 172.18.28.1, 00:02:41, Serial1/0
O IA 10.0.0.4 [110/165] via 172.18.28.1, 00:02:41, Serial1/0
答案是肯定的
7) 分割的Area 0
R2 和R4的RIPospf Area 0
R4#show ip os nei
Neighbor ID Pri State Dead Time Address Interface
10.0.0.2 0 FULL/ - 00:00:39 192.168.24.1 Serial1/0
R4#show ip route
O IA 172.18.28.0/30 [110/164] via 192.168.24.1, 00:00:11, Serial1/0
O IA 172.18.8.0/24 [110/174] via 192.168.24.1, 00:00:11, Serial1/0
O IA 172.18.2.0/24 [110/74] via 192.168.24.1, 00:00:11, Serial1/0
O IA 10.0.0.2 [110/65] via 192.168.24.1, 00:00:11, Serial1/0
R4收不到其他区域的路由,只有area的区域间路由
Area 2 增加一条V-LINK配置命令
R2(config)#router os 1
R2(config-router)#area 2 virtual-link 10.0.0.8
R8(config)#router os 1
R8(config-router)#area 2 virtual-link 10.0.0.2 //对端router-id
R4#show ip route ospf
172.17.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.17.13.0/30 [110/464] via 192.168.24.1, 00:00:18, Serial1/0
O IA 172.17.1.0/24 [110/374] via 192.168.24.1, 00:00:18, Serial1/0
O IA 172.17.3.0/24 [110/474] via 192.168.24.1, 00:00:18, Serial1/0
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
O E2 172.16.170.0/24 [110/10] via 192.168.24.1, 00:00:18, Serial1/0
O 172.16.17.0/30 [110/364] via 192.168.24.1, 00:00:18, Serial1/0
O 172.16.7.0/24 [110/274] via 192.168.24.1, 00:00:18, Serial1/0
O 172.16.78.0/30 [110/264] via 192.168.24.1, 00:00:18, Serial1/0
172.18.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.18.28.0/30 [110/164] via 192.168.24.1, 00:00:18, Serial1/0
O IA 172.18.8.0/24 [110/174] via 192.168.24.1, 00:00:18, Serial1/0
O IA 172.18.2.0/24 [110/74] via 192.168.24.1, 00:00:18, Serial1/0
10.0.0.0/32 is subnetted, 6 subnets
O 10.0.0.8 [110/165] via 192.168.24.1, 00:00:18, Serial1/0
O IA 10.0.0.2 [110/65] via 192.168.24.1, 00:00:18, Serial1/0
O IA 10.0.0.3 [110/465] via 192.168.24.1, 00:00:18, Serial1/0
O 10.0.0.1 [110/365] via 192.168.24.1, 00:00:18, Serial1/0
O 10.0.0.7 [110/265] via 192.168.24.1, 00:00:18, Serial1/0
O*E1 0.0.0.0/0 [110/2264] via 192.168.24.1, 00:00:18, Serial1/0
R4的路由正常了,就算隔离了AREA0,区域0的路由在R4上显示的也是区域内路由
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