因爲剛學OSPF路由協議，下面只是個人實驗結果，可能也有不準確的地方，請批評指正，謝謝
解決OSPF不規則區域
1、多進程雙向重分佈
2、Tunnel隧道
3、virtual-link
1、多進程雙向重分佈：
拓撲：
在R3上有兩個OSPF進程，當R3雙向多進程重分佈時，可以看到兩邊的路由都能學到
關鍵配置：
[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
#
這樣兩邊ospf能學到對方路由，但學到是LSA5類外部路由，額外提供LSA4類：
[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
拓撲：
tunnel做在R2、R3上，把tunnel宣告到Area0上，讓Area2看上去好像掛在骨幹區上
關鍵配置：
[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
#
這有個很奇怪的問題，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，並且產生一條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
重啓OSPF進程也一樣。也就是說，在華爲路由器上，沒有LSA5也可以產生LSA4，後來練習完下面的vlink-peer再返回來做這個練習，發現又正常了，R1上沒有LSA4，只有LSA3的路由，這個可能是緩存當時沒有得到徹底的清除所導致
利用tunnel的方法，可以看到R1上收到的Area2的路由是以LSA3類形式存在的，比用第一種雙向多進程重分佈要好點
3、virtual-link專業工具
拓撲：
vlink的方法在實際鏈路上仍然要傳遞hello報文，只不過由於組播不能超過一跳，單播報文
在R2、R3上配置vlink，關鍵配置：
[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
比較tunnel和vlink-peer，發現兩者都得到LSA3類路由，而且兩者都是p2p鏈路
vlink仍然是p2p類型：
[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類型：
[R3]dis ospf int all
OSPF Process 10 with Router ID93.3.3.3
Interfaces
Area: 0.0.0.0 (MPLS TE not enabled)
Interface: 100.1.1.3 (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
這兩者其實很像
和vlink一起的考試經常是說要在Area0上做區域認證，那麼請把vlink認證補全，這種問題其實在華爲路由器上特別簡單，只要在vlink-peer後面接着做相同的認證就可以了
補全不規則區域：
vlink-peer之貪吃蛇一
拓撲：
關鍵配置：
重點在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貪吃蛇二
拓撲：
在Area 1、Area 2、Area 3上做vlink，關鍵配置：
[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
#
這裏涉及到LSA3選路問題：
[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。
應該說R4關於1.1.1.1/32的路由從R2、R3收到，有兩條做負載均衡纔對，但這隻有一條。
真實的情況如下：
[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的兩條，Area 3的一條關於1.1.1.1/32主機路由，由於Area 2中同一條LSA比較metric，最後兩條是Area 2和Area 3的路由，它們的metric一樣，只不過所在Area區域不同，由於OSPF規定這樣的等價路由比較Area區域號，哪個大用哪個，所以ospf把92.2.2.2的1.1.1.1路由放入路由表中（區域零例外，因爲區域零最小）