OSPF Comprehensive experiment

About OSPF Irregular region problem
1、 Away from the backbone of the non backbone
2、 Discontinuous backbone

Better solution ：
Multi process bidirectional republication ;
ospf Multi process ： Multiple processes on a router , Each process has its own database , Calculate routing entries independently , And calculate all that are not shared ; Finally, all the best paths are loaded into the same routing table ;
An interface of a router can only work in one process ;
It can be used to solve irregular areas , Work irregular locations in different processes , Realize separation , Then we use the republishing technology to share the routing table ; It solves the problems of poor route selection and resource occupation

OSPF Optimize – Reduce LSA Update quantity of
1、 Summary — Reduce the number of routing entries in the backbone area
2、 Special area -- Reduce the number of routing entries in non backbone areas

【1】 Summary --OSPF The protocol does not support interface summary , In an area , Topological information is transmitted between adjacency , Cannot summarize ; Therefore, it can only be summarized at the boundary equipment of interactive routing

**1） Inter domain routing summary –** Between regions ABR On , Perform summary configuration when interacting with inter area routing entries
[r2]ospf 1
[r2-ospf-1]area 1 Locally through this area 1/2 class LSA Calculated route , It can be summarized and passed to other areas
[r2-ospf-1-area-0.0.0.1]abr-summary 3.3.0.0 255.255.252.0

2） Extraterritorial routing summary -–ASBR The external routing entries are passed through the republication protocol , Share to OSPF When in the agreement, you can summarize

【2】 Special area – It is used to reduce the cost of each non backbone area LSA Number
Cannot be a backbone area , Virtual link cannot be configured

[1] At the same time, it cannot exist ASBR
**1） The terminal area –** Refuse 4/5 Class LSA; The backbone area is connected by this area ABR Post a message to this area 3 Class
notes ： All routers in this area need to configure this command

2） Completely peripheral area Based on the peripheral region , Further reject 3 Class LSA; Keep only one 3 Class
First, configure all routers in the whole area as the end area ; Then only in the area connecting the backbone ABR Complete configuration on the

[2] There is ASBR

1)NSSA Incomplete ending area – This area will reject 4/5 class LSA, The backbone area is connected by this area ABR Post a message to this area 7 Class ; In this area ASBR When importing extraterritorial routes , be based on 7 Class import , Then connect the backbone through this area ABR When passing to the backbone area , Convert to 5 Class enters the backbone area ;
NSSA The point of design , Not to reduce... In this area ASBR The resulting extraterritorial route , But other parts of the network ASBR The resulting extraterritorial route ;

2） complete NSSA — stay NSSA On the basis of , Further reject 3 class LSA To enter , The backbone area is connected by this area ABR Post a message to this area 3 Class
First, configure the area as NSSA Area , After that, only the backbone is connected in this area ABR Complete configuration on the

Bear in mind ：NSSA And completely NSSA Working environment , You need to consider ISP（ Operator, ） The position of , Otherwise, the loop may appear

The experimental requirements ：

1.R4 by ISP, Can only be configured on it IP Address ;R4 Use public with all other directly connected devices IP Address ;
2.R3-R5/6/7 by MGRE Environmental Science ,R3 For the central site ;
3. Whole OSPF Environmental Science IP The address is 172.16.0.0/16;
4. All devices are accessible R4 The loopback of ;
5. Reduce LSA Update quantity of , Speed up convergence , To ensure the security of updates ;
6. Network wide accessibility ！

The topology ：

IP planning ：
172.16.0.0/16
Because there are six areas , So will IP Divided into 6 Net segment ,2^3=8, Among them, some sub network segments are further divided ,P2P Backbone links 、MA Allocate appropriate network segments on backbone links and other routers
172.16.0.0/16
need 6 Regions

172.16.0.0/19 area0
172.16.0.0/25 172.168.0.128/25 172.168.1.0/25 172.168.1.128…
172.16.0.0/25 p2p Backbone links 172.16.0.0/30 172.16.0.4/30…
172.16.0.128/25 MA Backbone links 172.16.0.128、29 172.16.0.136/29…

172.16.32.0/19

172.16.64.0/19

172.16.96.0/19

172.16.128.0/19

172.16.160.0/19

172.16.192.0/19

172.16.224.0/19

First configure area0 Area

1、 First configure the interface IP
[r3-GigabitEthernet0/0/1]ip add 34.1.1.1 24

[r4-GigabitEthernet0/0/0]ip add 34.1.1.2 24
[r4-GigabitEthernet0/0/1]ip add 45.1.1.2 24
[r4-GigabitEthernet0/0/2]ip add 46.1.1.2 24 
[r4-GigabitEthernet4/0/0]ip add 47.1.1.2 24

[r5-GigabitEthernet0/0/0]ip add 45.1.1.1 24

[r6-GigabitEthernet0/0/0]ip add 46.1.1.1 24

[r7-GigabitEthernet0/0/0]ip add 47.1.1.1 24
2、 Configure the default route 
[r3]ip route-static 0.0.0.0 0 34.1.1.2
[r5]ip route-static 0.0.0.0 0 45.1.1.2 
[r6]ip route-static 0.0.0.0 0 46.1.1.2 
[r7]ip route-static 0.0.0.0 0 47.1.1.2

 With r4 For the central site , To configure mgre
[r3]int t0/0/0
[r3-Tunnel0/0/0]ip add 172.16.0.129 24
[r3-Tunnel0/0/0]tunnel-protocol gre p2mp 
[r3-Tunnel0/0/0]source 34.1.1.1
[r3-Tunnel0/0/0]nhrp entry multicast dynamic 
[r3-Tunnel0/0/0]nhrp network-id 100
[r3-Tunnel0/0/0]ip add 172.16.0.129 29

[r5]int t0/0/0
[r5-Tunnel0/0/0]ip add 172.16.0.130 29
[r5-Tunnel0/0/0]tunnel-protocol gre p	
[r5-Tunnel0/0/0]tunnel-protocol gre p2mp 
[r5-Tunnel0/0/0]source g0/0/0
[r5-Tunnel0/0/0]nhrp ent 172.16.0.129 34.1.1.1 register 
[r5-Tunnel0/0/0]nhrp network-id 100

[r6]int t0/0/0
[r6-Tunnel0/0/0]ip add 172.16.0.131 29
[r6-Tunnel0/0/0]tunnel-protocol gre p2mp 
[r6-Tunnel0/0/0]source g0/0/0
[r6-Tunnel0/0/0]nhrp entry 172.16.0.129 34.1..1.1 register 
[r6-Tunnel0/0/0]nhrp network-id 100

[r7]int t0/0/0
[r7-Tunnel0/0/0]ip add 172.16.0.132 29
[r7-Tunnel0/0/0]tunnel-protocol gre p2mp 
[r7-Tunnel0/0/0]source g0/0/0
[r7-Tunnel0/0/0]nhrp entry 172.16.0.129 34.1.1.1 register 
[r7-Tunnel0/0/0]nhrp network-id 100

test
stay r3 On ping R5/R6/R7 The private address of

stay R3,R5,R6,R7 Do on nat

[r5]acl 2000
[r5-acl-basic-2000]rule permit source any
[r5-acl-basic-2000]int g0/0/0
[r5-GigabitEthernet0/0/0]nat outbound 2000

rest 3 The same goes for Taiwan
test ：

Configure interface IP And loopback interface
area0

r1

r2：

r3：

area2：
r6

R11:

R12:

area3
R7:

R8:

R9:

area4:
R9:

R10:

area5
R12

start-up OSPF agreement , And configuration Area 0/1/2/3/4 Area ; As well as the configuration rip agreement

[r1]ospf 1 router-id 1.1.1.1
[r1-ospf-1]area 1
[r1-ospf-1-area-0.0.0.1]network 172.16.0.0 0.0.255.255

[r2]ospf 1 router-id 2.2.2.2
[r2-ospf-1]area 1
[r2-ospf-1-area-0.0.0.1]  network 172.16.0.0 0.0.255.255 

[r3]ospf 1 router-id 3.3.3.3
[r3-ospf-1]area 1
[r3-ospf-1-area-0.0.0.1]net 172.16.32.0 0.0.3.255
[r3-ospf-1-area-0.0.0.1]area 0
[r3-ospf-1-area-0.0.0.0]net 172.16.0.129 0.0.0.0

[r5]ospf 1 router-id 5.5.5.5
[r5-ospf-1]area 0
[r5-ospf-1-area-0.0.0.0]net 172.16.0.0 0.0.255.255

[r6]ospf 1 router-id 6.6.6.6
[r6-ospf-1]area 0
[r6-ospf-1-area-0.0.0.0]net 172.16.0.0 0.0.1.255                       
[r6-ospf-1-area-0.0.0.1]area 2
[r6-ospf-1-area-0.0.0.2]net 172.16.64.1 0.0.0.0

[r7]ospf 1 router-id 7.7.7.7
[r7-ospf-1]area 0
[r7-ospf-1-area-0.0.0.0]net 172.16.0.0 0.0.3.255
[r7-ospf-1-area-0.0.0.0]area 3
[r7-ospf-1-area-0.0.0.3]net 172.16.96.1 0.0.0.0

[r8]ospf 1 router-id  8.8.8.8
[r8-ospf-1]area 3
[r8-ospf-1-area-0.0.0.3]net 172.16.0.0 0.0.255.255

[r9]ospf 1 router-id  9.9.9.9
[r9-ospf-1]area 3
[r9-ospf-1-area-0.0.0.3]network 172.16.96.6 0.0.0.0
[r9-ospf-1-area-0.0.0.3]area 4
[r9-ospf-1-area-0.0.0.4]net 172.16.128.0 0.0.1.255

[r10]ospf 1 router-id 
[r10]ospf 1 router-id 10.10.10.10
[r10-ospf-1]area 4
[r10-ospf-1-area-0.0.0.4]net 172.16.0.0 0.0.255.255

[r11]ospf 1 router-id 11.11.11.11
[r11-ospf-1]area 2
[r11-ospf-1-area-0.0.0.2]net 172.16.0.0 0.0.255.255

[r12]ospf 1 router-id 12.12.12.12
[r12-ospf-1]area 2
[r12-ospf-1-area-0.0.0.2]net 172.16.64.6 0.0.0.0
[r12]rip 1 
[r12-rip-1]v 2
[r12-rip-1]net 172.16.0.0

 take RIP Republish to OSPF in ;
[R12]ospf 1 
[R12-ospf-1]import-route rip 1

Check whether the neighborhood relationship is established ：

modify MGRE Interface network type of environment , And will R5、6、7 Of dr-priority Change it to 0

[R3]interface Tunnel 0/0/0
[R3-Tunnel0/0/0]ospf network-type broadcast

[R5]interface Tunnel 0/0/0
[R5-Tunnel0/0/0]ospf network-type broadcast 
[R5-Tunnel0/0/0]ospf dr-priority 0

test ;
At this point, all protocols are configured , Start testing ;
Check neighbors in key locations ;
r3 Neighbor relationship table

r6 Neighbor relationship table

r7 Neighbor relationship table

r9 Neighbor relationship table

solve area 3 and area 4 Communication problems （ It is generally recommended to republish ）;

[R9]undo ospf 1
Warning: The OSPF process will be deleted. Continue? [Y/N]:y
[R9]ospf 1 router-id 9.9.9.9
[R9-ospf-1]area 3
[R9-ospf-1-area-0.0.0.3]network 172.16.96.6 0.0.0.0
[R9-ospf-1-area-0.0.0.3]ospf 2
[R9-ospf-2]area 4
[R9-ospf-2-area-0.0.0.4]net 172.16.128.0 0.0.0.255

Now our OSPF 1 It's equivalent to the original Area 3,OSPF 2 It's equivalent to the original Area 4;
Then we will OSPF 2 Republish to OSPF 1 Just go to the middle ！ There is no need to republish in both directions , Because in the end, just give OSPF 2 Issue a default ！

[R9]ospf 1
[R9-ospf-1]import-route ospf  2

Look at the neighborhood table ：

View the link status database ：

R5 Link state database ：

Next , We reduce lsa Update quantity of , For its in each area abr Summary on

[r3]ospf 1
[r3-ospf-1]area 1
[r3-ospf-1-area-0.0.0.1]abr-summary 172.16.32.0 255.255.224.0

[r6]ospf 1
[r6-ospf-1]area 2
[r6-ospf-1-area-0.0.0.2]abr-summary 172.16.64.0 255.255.224.0

[r7]ospf 1
[r7-ospf-1]area 3
[r7-ospf-1-area-0.0.0.3]abr-summary 172.16.96.0 255.255.224.0

[r9]ospf 1
[r9-ospf-1]asbr-summary 172.16.128.0 255.255.224.0

[r12]ospf 1
[r12-ospf-1]asbr-summary 172.16.160.0 255.255.224.0

Now in the backbone area LSDB It has been reduced to the minimum ;
Then configure special areas , To continue to alleviate ：
Area 1 Can be a stub Area ：

[R1]ospf 1
[R1-ospf-1]area 1
[R1-ospf-1-area-0.0.0.1]stub 
[R2-ospf-1]area 1
[R2-ospf-1-area-0.0.0.1]stub 
[R3-ospf-1-area-0.0.0.1]stub no-summary

see R5 The aggregated routing information on ：

Area 2 Can be a nssa Area ：

[R6-ospf-1-area-0.0.0.2]nssa
[R11-ospf-1-area-0.0.0.2]nssa
[R12-ospf-1-area-0.0.0.2]nssa

Area 2 Can become completely nssa Area ：

[R6-ospf-1-area-0.0.0.2]nssa  no-summary

Three types of lsa default ：

[R7-ospf-1-area-0.0.0.3]nssa no-summary
[R8-ospf-1-area-0.0.0.3]nssa
[R9-ospf-1-area-0.0.0.3]nssa

Solution area 4 Communication with other regions , Give area 4 Drop the default route ;

[R9-ospf-2]default-route-advertise

We go back to R5 Check out ospf The routing , It is found that the number of routes is greatly reduced .

Achieve the ultimate goal ！