因为刚学OSPF路由协议，下面只是个人实验结果，可能也有不准确的地方，请批评指正，谢谢
解决OSPF不规则区域
1、多进程双向重分布
2、Tunnel隧道
3、virtual-link
1、多进程双向重分布：
拓扑：
在R3上有两个OSPF进程，当R3双向多进程重分布时，可以看到两边的路由都能学到
关键配置：
[R1]dis cur
#
sysname R1
#
router id 91.1.1.1
#
interface Serial0/0/0
link-protocol ppp
ip address 12.1.1.1 255.255.255.0
#
interface LoopBack0
ip address 1.1.1.1 255.255.255.0
#
ospf 10
area 0.0.0.0
network 1.1.1.1 0.0.0.0
network 12.1.1.1 0.0.0.0
#
[R2]dis cur
#
sysname R2
#
router id 92.2.2.2
#
interface Serial0/0/0
link-protocol ppp
ip address 12.1.1.2 255.255.255.0
#
interface Serial0/0/1
link-protocol ppp
ip address 23.1.1.2 255.255.255.0
#
interface LoopBack0
ip address 2.2.2.2 255.255.255.0
#
ospf 10
area 0.0.0.0
network 2.2.2.2 0.0.0.0
network 12.1.1.2 0.0.0.0
area 0.0.0.1
network 23.1.1.2 0.0.0.0
#
[R3]dis cur
#
sysname R3
#
router id 93.3.3.3
#
interface Serial0/0/0
link-protocol ppp
ip address 34.1.1.3 255.255.255.0
#
interface Serial0/0/1
link-protocol ppp
ip address 23.1.1.3 255.255.255.0
#
interface LoopBack0
ip address 3.3.3.3 255.255.255.0
#
ospf 10
import-route ospf 100
area 0.0.0.1
network 3.3.3.3 0.0.0.0
network 23.1.1.3 0.0.0.0
#
ospf 100
import-route ospf 10
area 0.0.0.0
network 34.1.1.3 0.0.0.0
#
[R4]dis cur
#
sysname R4
#
router id 94.4.4.4
#
interface Serial0/0/0
link-protocol ppp
ip address 34.1.1.4 255.255.255.0
#
interface LoopBack0
ip address 4.4.4.4 255.255.255.0
#
ospf 100
area 0.0.0.0
network 4.4.4.4 0.0.0.0
network 34.1.1.4 0.0.0.0
#
这样两边ospf能学到对方路由，但学到是LSA5类外部路由，额外提供LSA4类：
[R4]dis ip rou p os
Route Flags: R - relay, D - downloadto fib
------------------------------------------------------------------------------
Public routing table : OSPF
Destinations : 5 Routes : 5
OSPF routing table status :<Active>
Destinations : 5 Routes : 5
Destination/Mask Proto Pre Cost Flags NextHop Interface
1.1.1.1/32 O_ASE 150 1 D 34.1.1.3 Serial0/0/0
2.2.2.2/32 O_ASE 150 1 D 34.1.1.3 Serial0/0/0
3.3.3.0/24 O_ASE 150 1 D 34.1.1.3 Serial0/0/0
12.1.1.0/24 O_ASE 150 1 D 34.1.1.3 Serial0/0/0
23.1.1.0/24 O_ASE 150 1 D 34.1.1.3 Serial0/0/0
2、Tunnel隧道
拓扑：
tunnel做在R2、R3上，把tunnel宣告到Area0上，让Area2看上去好像挂在骨干区上
关键配置：
[R2]dis cur
#
sysname R2
#
router id 92.2.2.2
#
interface Serial0/0/0
link-protocol ppp
ip address 12.1.1.2 255.255.255.0
#
interface Serial0/0/1
link-protocol ppp
ip address 23.1.1.2 255.255.255.0
#
interface LoopBack0
ip address 2.2.2.2 255.255.255.0
#
interface Tunnel0/0/0
ip address 100.1.1.2 255.255.255.0
tunnel-protocol gre
source 23.1.1.2
destination 23.1.1.3
#
ospf 10
area 0.0.0.0
network 2.2.2.2 0.0.0.0
network 12.1.1.2 0.0.0.0
network 100.1.1.2 0.0.0.0
area 0.0.0.1
network 23.1.1.2 0.0.0.0
#
[R3]dis cur
#
sysname R3
#
router id 93.3.3.3
#
interface Serial0/0/0
link-protocol ppp
ip address 34.1.1.3 255.255.255.0
#
interface LoopBack0
ip address 3.3.3.3 255.255.255.0
#
interface Tunnel0/0/0
ip address 100.1.1.3 255.255.255.0
tunnel-protocol gre
source 23.1.1.3
destination 23.1.1.2
#
ospf 10
import-route ospf 100 cost 2 type 1 tag 100
area 0.0.0.0
network 100.1.1.3 0.0.0.0
area 0.0.0.1
network 3.3.3.3 0.0.0.0
network 23.1.1.3 0.0.0.0
area 0.0.0.2
network 34.1.1.3 0.0.0.0
#
这有个很奇怪的问题，在R1上：
[R1]dis ospf abr-asbr
OSPF Process 10 with Router ID91.1.1.1
Routing Table to ABR and ASBR
RtType Destination Area Cost Nexthop Type
Intra-area 92.2.2.2 0.0.0.0 1562 12.1.1.2 ABR
Intra-area 93.3.3.3 0.0.0.0 3124 12.1.1.2 ABR/ASBR
[R1]dis ospf asbr
OSPF Process 10 with Router ID91.1.1.1
[R1]dis ospf lsdb
OSPF Process 10 with Router ID91.1.1.1
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 92.2.2.2 92.2.2.2 1562 84 80000003 1562
Router 91.1.1.1 91.1.1.1 1563 60 80000002 0
Router 93.3.3.3 93.3.3.3 1563 48 80000002 1562
Sum-Net 23.1.1.0 92.2.2.2 1573 28 80000001 1562
Sum-Net 23.1.1.0 93.3.3.3 1572 28 80000001 1562
Sum-Net 3.3.3.3 92.2.2.2 1563 28 80000001 1562
Sum-Net 3.3.3.3 93.3.3.3 1572 28 80000001 0
Sum-Net 4.4.4.4 93.3.3.3 1563 28 80000001 1562
Sum-Net 34.1.1.0 93.3.3.3 1572 28 80000001 1562
Sum-Asbr 93.3.3.3 92.2.2.2 1563 28 80000001 1562
R2居然通告R3是ASBR，并且产生一条LSA4
[R1]dis ospf lsdb asbr
OSPF Process 10 with Router ID91.1.1.1
Area: 0.0.0.0
Link State Database
Type : Sum-Asbr
Ls id : 93.3.3.3
Adv rtr : 92.2.2.2
Ls age : 1648
Len : 28
Options : E
seq# : 80000001
chksum : 0xe65
Tos 0 metric: 1562
重启OSPF进程也一样。也就是说，在华为路由器上，没有LSA5也可以产生LSA4，后来练习完下面的vlink-peer再返回来做这个练习，发现又正常了，R1上没有LSA4，只有LSA3的路由，这个可能是缓存当时没有得到彻底的清除所导致
利用tunnel的方法，可以看到R1上收到的Area2的路由是以LSA3类形式存在的，比用第一种双向多进程重分布要好点
3、virtual-link专业工具
拓扑：
vlink的方法在实际链路上仍然要传递hello报文，只不过由于组播不能超过一跳，单播报文
在R2、R3上配置vlink，关键配置：
[R2]dis cur config ospf
#
ospf 10
area 0.0.0.0
network 2.2.2.2 0.0.0.0
network 12.1.1.2 0.0.0.0
area 0.0.0.1
network 23.1.1.2 0.0.0.0
vlink-peer 93.3.3.3
#
[R3]dis cur config ospf
#
ospf 10
area 0.0.0.1
network 3.3.3.3 0.0.0.0
network 23.1.1.3 0.0.0.0
vlink-peer 92.2.2.2
area 0.0.0.2
network 34.1.1.3 0.0.0.0
#
看到
[R1]dis ospf lsdb summary 4.4.4.4
OSPF Process 10 with Router ID91.1.1.1
Area: 0.0.0.0
Link State Database
Type : Sum-Net
Ls id : 4.4.4.4
Adv rtr : 93.3.3.3
Ls age : 510
Len : 28
Options : E
seq# : 80000003
chksum : 0x6262
Net mask : 255.255.255.255
Tos 0 metric: 1562
Priority : Medium
[R1]dis ip rou
Route Flags: R - relay, D - downloadto fib
------------------------------------------------------------------------------
Routing Tables: Public
Destinations : 12 Routes : 12
Destination/Mask Proto Pre Cost Flags NextHop Interface
1.1.1.0/24 Direct 0 0 D 1.1.1.1 LoopBack0
1.1.1.1/32 Direct 0 0 D 127.0.0.1 LoopBack0
2.2.2.2/32 OSPF 10 1562 D 12.1.1.2 Serial0/0/0
3.3.3.3/32 OSPF 10 3124 D 12.1.1.2 Serial0/0/0
4.4.4.4/32 OSPF 10 4686 D 12.1.1.2 Serial0/0/0
12.1.1.0/24 Direct 0 0 D 12.1.1.1 Serial0/0/0
12.1.1.1/32 Direct 0 0 D 127.0.0.1 Serial0/0/0
12.1.1.2/32 Direct 0 0 D 12.1.1.2 Serial0/0/0
23.1.1.0/24 OSPF 10 3124 D 12.1.1.2 Serial0/0/0
34.1.1.0/24 OSPF 10 4686 D 12.1.1.2 Serial0/0/0
127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0
127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0
比较tunnel和vlink-peer，发现两者都得到LSA3类路由，而且两者都是p2p链路
vlink仍然是p2p类型：
[R2]dis ospf vlink
OSPF Process 10 with Router ID92.2.2.2
Virtual Links
Virtual-link Neighbor-id -> 93.3.3.3, Neighbor-State: Full
Interface: 23.1.1.2 (Serial0/0/1)
Cost: 1562 State: P-2-P Type: Virtual
Transit Area: 0.0.0.1
Timers: Hello 10 , Dead 40 , Retransmit 5 ,Transmit Delay 1
tunnel也是p2p类型：
[R3]dis ospf int all
OSPF Process 10 with Router ID93.3.3.3
Interfaces
Area: 0.0.0.0 (MPLS TE not enabled)
Tunnel0/0/0)--> 100.1.1.2
Cost: 1562 State: P-2-P Type: P2P MTU: 1500
Timers: Hello 10 , Dead 40 , Poll 120 , Retransmit 5 , Transmit Delay 1
这两者其实很像
和vlink一起的考试经常是说要在Area0上做区域认证，那么请把vlink认证补全，这种问题其实在华为路由器上特别简单，只要在vlink-peer后面接着做相同的认证就可以了
补全不规则区域：
vlink-peer之贪吃蛇一
拓扑：
关键配置：
重点在Area1和Area2上配置vlink即可
[R1]dis cur
#
sysname R1
#
router id 91.1.1.1
#
interface Serial0/0/0
link-protocol ppp
ip address 12.1.1.1 255.255.255.0
#
interface LoopBack0
ip address 1.1.1.1 255.255.255.0
#
ospf 10
area 0.0.0.0
network 1.1.1.1 0.0.0.0
network 12.1.1.1 0.0.0.0
#
[R2]dis cur
#
sysname R2
#
router id 92.2.2.2
#
interface Serial0/0/0
link-protocol ppp
ip address 12.1.1.2 255.255.255.0
#
interface Serial0/0/1
link-protocol ppp
ip address 23.1.1.2 255.255.255.0
#
interface LoopBack0
ip address 2.2.2.2 255.255.255.0
#
ospf 10
area 0.0.0.0
network 2.2.2.2 0.0.0.0
network 12.1.1.2 0.0.0.0
area 0.0.0.1
network 23.1.1.2 0.0.0.0
vlink-peer 93.3.3.3
#
[R3]dis cur
#
sysname R3
#
router id 93.3.3.3
#
interface Serial0/0/0
link-protocol ppp
ip address 34.1.1.3 255.255.255.0
#
interface Serial0/0/1
link-protocol ppp
ip address 23.1.1.3 255.255.255.0
#
interface LoopBack0
ip address 3.3.3.3 255.255.255.0
#
ospf 10
area 0.0.0.1
network 3.3.3.3 0.0.0.0
network 23.1.1.3 0.0.0.0
vlink-peer 92.2.2.2
area 0.0.0.2
network 34.1.1.3 0.0.0.0
vlink-peer 94.4.4.4
#
[R4]dis cur
#
sysname R4
#
router id 94.4.4.4
#
interface Serial0/0/0
link-protocol ppp
ip address 34.1.1.4 255.255.255.0
#
interface Serial0/0/1
link-protocol ppp
ip address 45.1.1.4 255.255.255.0
#
interface LoopBack0
ip address 4.4.4.4 255.255.255.0
#
ospf 10
area 0.0.0.2
network 4.4.4.4 0.0.0.0
network 34.1.1.4 0.0.0.0
vlink-peer 93.3.3.3
area 0.0.0.3
network 45.1.1.4 0.0.0.0
#
[R5]dis cur
#
sysname R5
#
router id 95.5.5.5
#
interface Serial0/0/1
link-protocol ppp
ip address 45.1.1.5 255.255.255.0
#
interface LoopBack0
ip address 5.5.5.5 255.255.255.0
#
ospf 10
area 0.0.0.3
network 5.5.5.5 0.0.0.0
network 45.1.1.5 0.0.0.0
#
vlink-peer贪吃蛇二
拓扑：
在Area 1、Area 2、Area 3上做vlink，关键配置：
[R1]dis cur
#
sysname R1
#
router id 91.1.1.1
#
interface Serial0/0/0
link-protocol ppp
ip address 12.1.1.1 255.255.255.0
#
interface Serial0/0/1
link-protocol ppp
ip address 13.1.1.1 255.255.255.0
#
interface LoopBack0
ip address 1.1.1.1 255.255.255.0
#
ospf 10
area 0.0.0.0
network 1.1.1.1 0.0.0.0
network 13.1.1.1 0.0.0.0
area 0.0.0.1
network 12.1.1.1 0.0.0.0
vlink-peer 92.2.2.2
#
[R2]dis cur
#
sysname R2
#
router id 92.2.2.2
#
interface Serial0/0/0
link-protocol ppp
ip address 12.1.1.2 255.255.255.0
#
interface Serial0/0/1
link-protocol ppp
ip address 24.1.1.2 255.255.255.0
#
interface LoopBack0
ip address 2.2.2.2 255.255.255.0
#
ospf 10
area 0.0.0.1
network 2.2.2.2 0.0.0.0
network 12.1.1.2 0.0.0.0
vlink-peer 91.1.1.1
area 0.0.0.3
network 24.1.1.2 0.0.0.0
vlink-peer 94.4.4.4
#
[R3]dis cur
#
sysname R3
#
router id 93.3.3.3
#
interface Serial0/0/0
link-protocol ppp
ip address 34.1.1.3 255.255.255.0
#
interface Serial0/0/1
link-protocol ppp
ip address 13.1.1.3 255.255.255.0
#
interface LoopBack0
ip address 3.3.3.3 255.255.255.0
#
ospf 10
area 0.0.0.0
network 13.1.1.3 0.0.0.0
area 0.0.0.2
network 34.1.1.3 0.0.0.0
network 3.3.3.3 0.0.0.0
vlink-peer 94.4.4.4
#
[R4]dis cur
#
sysname R4
#
router id 94.4.4.4
#
interface Serial0/0/0
link-protocol ppp
ip address 34.1.1.4 255.255.255.0
#
interface Serial0/0/1
link-protocol ppp
ip address 24.1.1.4 255.255.255.0
#
interface LoopBack0
ip address 4.4.4.4 255.255.255.0
#
ospf 10
area 0.0.0.2
network 34.1.1.4 0.0.0.0
vlink-peer 93.3.3.3
area 0.0.0.3
network 4.4.4.4 0.0.0.0
network 24.1.1.4 0.0.0.0
vlink-peer 92.2.2.2
#
这里涉及到LSA3选路问题：
[R4]dis ip routing-table
Route Flags: R - relay, D - downloadto fib
------------------------------------------------------------------------------
Routing Tables: Public
Destinations : 15 Routes : 15
Destination/Mask Proto Pre Cost Flags NextHop Interface
1.1.1.1/32 OSPF 10 3124 D 24.1.1.2 Serial0/0/1
2.2.2.2/32 OSPF 10 1562 D 24.1.1.2 Serial0/0/1
3.3.3.3/32 OSPF 10 1562 D 34.1.1.3 Serial0/0/0
4.4.4.0/24 Direct 0 0 D 4.4.4.4 LoopBack0
以下略。
应该说R4关于1.1.1.1/32的路由从R2、R3收到，有两条做负载均衡才对，但这只有一条。
真实的情况如下：
[R4]dis ospf lsdb
OSPF Process 10 with Router ID 94.4.4.4
Link State Database
Area: 0.0.0.0
略
Area: 0.0.0.2
Type LinkState ID AdvRouter Age Len Sequence Metric
Sum-Net 1.1.1.1 94.4.4.4 940 28 80000002 3124
Sum-Net 1.1.1.1 93.3.3.3 1275 28 80000001 1562
Area: 0.0.0.3
Type LinkState ID AdvRouter Age Len Sequence Metric
Sum-Net 1.1.1.1 92.2.2.2 960 28 80000002 1562
可以看到，R4收到Area 2的两条，Area 3的一条关于1.1.1.1/32主机路由，由于Area 2中同一条LSA比较metric，最后两条是Area 2和Area 3的路由，它们的metric一样，只不过所在Area区域不同，由于OSPF规定这样的等价路由比较Area区域号，哪个大用哪个，所以ospf把92.2.2.2的1.1.1.1路由放入路由表中（区域零例外，因为区域零最小）
转载于:https://blog.51cto.com/happyln/1652777
