Optimization and configuration of OSPF

OSPF The optimization of the
1、 Summary
Reduce the of backbone area LSA Number
OSPF The summary of is different from RIP Interface summary , It is called Regional summary . because OSPF Routing information is passed between regions
1、 Inter domain routing summary
It's essentially through ABR Three types of transmission between areas on the device LSA To summarize
Be careful ： Inter domain routing summary can only be summarized ABR The device itself passes 1 class ,2 class LSA Information learned routing information
2、 Extraterritorial routing summary
In essence, it is in ASBR On , By republishing , Will be imported 5 class /7 class LSA Get into OSPF Summarize after the network
type1
The cost value of the summary network segment is equal to the maximum of all detailed routing cost values plus 1
type2
The cost value of the summary network segment is equal to the maximum of all detailed routing cost values

2、 Special area
Reduce non backbone areas LSA Number
OSPF In general, it can be divided into two categories , Four sub categories

The first category of conditions ：
1、 It can't be the backbone area
2、 Virtual links cannot exist
3、 Can't exist ASBR equipment
The first category is divided into ：
1、 The terminal area
If an area is configured as a terminal area , Then this area will no longer learn 4 Classes and 5 class LSA. Such an area will refuse to learn extraterritorial routing information , however , It still has the need to access extraterritorial routes , all , When the configuration is complete , It will automatically generate a line pointing to the backbone area 3 Class default
Configure the end area ---- stub
Be careful ： Once you make a special area , Then the equipment in all areas must be made into special areas
2、 Complete end routing
Based on the peripheral region , Further refuse to learn 3 class LSA, Keep only 3 Class defaults
Configure the full end area ---- stub no-summary

The second category of conditions ：
1、 It can't be the backbone area
2、 Virtual links cannot exist
3、 There is ASBR equipment
The second category is divided into ：
1、 Incomplete ending area
This area is no longer learning 4 Classes and 5 class LSA, The region still needs to import the following extraterritorial routing information , For refusing 5 class , therefore , Only with 7 class LSA To continue to pass , Such an area will refuse to learn extraterritorial routing information , however , It still has the need to access extraterritorial routes , therefore , When the configuration is complete , It will automatically generate a line pointing to the backbone area 7 Class default
Configure incomplete end regions ---- nssa
2、 Complete and incomplete peripheral regions
stay NSSA On a regional basis , Further refuse to learn 3 class LSA, Generate a 3 Class defaults
Configure complete and incomplete terminal areas ---- nssa no-summary
Be careful ： The automatically generated default must be in the same direction as the manually added default , Otherwise, a loop may appear

OSPF Extended configuration
1、 Manual certification
Certification is in OSPF In all packets interacting with neighbors , Carry password . Password is the same. , Then the identity is legal
Certification is divided into 3 Kind of ：
1、 Interface authentication
Configure on the interface of neighbor communication
ospf authentication-mode md5 1 cipher 123456
Be careful ： Configured on both sides key id It has to be the same , Otherwise, the neighbor relationship authentication will fail
2、 Regional certification
Its essence is interface authentication , It is equivalent to configuring interface authentication for all interfaces activated in a certain area at one time
authentication-mode md5 1 cipher 123456
3、 Virtual link authentication
Add authentication in the virtual link establishment stage , Its essence is also interface authentication
vlink-peer 3.3.3.3 md5 1 cipher 123456

2、 Speed up convergence
Reduce timer time

1、 modify hello Time
2、 Modify the time of death

3、 Silent interface
Configure an interface as a silent interface , Then this interface will only accept and not send ospf Data packets of
The silent interface will take effect for unicast and multicast packets
silent-interface G 0/0/2

4、 Default route
1、3 Class default
It can only be generated automatically through special areas , Common terminal area , Completely peripheral area , Complete and incomplete peripheral regions
characteristic ： Marked as ospf, The default priority is 10
2、5 Class default
The default generated by manual configuration
characteristic ： Marked as O_ASE, The default priority is 150
3、7 Class default
It can be automatically distributed by configuring special areas , You can also issue a manual command 7 Class default

5、 Route filtering
ospf Targeted at 3 class ,5 class ,7 class LSA To filter
Filter 3 class LSA
abr-summary 192.168.0.0 255.255.252.0 not-advertise
Filter 5 class /7 class LSA
asbr-summary 172.16.0.0 255.255.252.0 not-advertise