Link expansion configuration of OSPF

 

All that carry routing information LSA All need to pass 1 Classes and 2 class LSA Check calculation .---- The so-called checking calculation means that the location information of the notifier who transmits the routing information needs to pass 1 class ,2 class LSA The information is calculated .

Type-5LSA

Metric（cost）---5 class LSA Carry through Republish the imported extraterritorial routing information , Because different networks have different evaluation standards for metrics , therefore , When the extraterritorial route is imported into the network , We will abandon its original cost value , And give him a defined value ---seed-metric ---- Seed measure .OSPF The default seed metric in the network is 1.

[r4-ospf-1]import-route rip 1 cost 10

--- stay Modify the seed measure when republishing

E Type--- A marker bit , When Mark position 0 when , For use type 1; When the mark

Location 1 when , For use type 2 ---- It refers to the type of cost value ---OSPF agreement

Default usage type 2.

type 1： If the cost value type is type 1, Then within the domain The cost value of all devices arriving at the target network segment outside the domain is equal to the cost value of local arrival notifier plus the seed measurement .

[r4-ospf-1]import-route rip 1 type 1

--- Modify the cost value type when republishing

type 2： If the cost value type is type 2, be All devices in the domain reach the target outside the domain

The cost value of the network segment is equal to the seed measure .

Forwarding Address--- Forwarding address --- One Redirect address , Be similar to RIPV2 

Next hop field in , pawn out The current route is not good The situation of , Then the best routing information will be carried in this field , be We will find the next hop according to the forwarding address , Instead of searching for notifiers according to the algorithm .5 class LSA in , stay There is no poor choice Under the circumstances , take Use 0.0.0.0  To fill in .

Tag--- Routing tags --- Sure to 5 class LSA Marking , It's convenient to catch by marking

Intake flow .

[r4-ospf-1]import-route rip 1 tag ?

INTEGER<0-4294967295> Tag value

Type-4 LSA --- auxiliary 5 class LSA Complete the checking process , find ASBR The location of . There is only one cost value in it , It refers to the arrival of the announcer ASBR The cost of .

 

V --- Set up 1, It means that the router is VLINK An endpoint of  

E --- Set up 1, It means that the router is ASBR equipment  

B --- Set up 1, It means that the router is Area boundary equipment ABR.

OSPF Of Optimize

1, Summary --- Reduce the of backbone area LSA Number  

2, Special area --- Reduce non backbone areas LSA Number

Summary ：

OSPF The summary of is different from RIP Interface summary , It is called Regional summary . because OSPF stay What is passed between regions is Routing information .

1, Inter domain routing summary --- Is essentially By means of ABR Three types of transmission between areas on the device LSA To summarize

[r1-ospf-1-area-0.0.0.2]abr-summary 192.168.0.0 255.255.252.0

Be careful ： Inter domain routing summary can only be summarized ABR The device itself passes 1 class ,2 class LSA Information learning To Routing information for .

2, Extraterritorial routing summary --- Its The essence is ASBR On , By republishing , Will be imported 5 

class /7 class LSA Enter into OSPF Summarize after the network .

[r4-ospf-1]asbr-summary 172.16.0.0 255.255.252.0

Be careful ：5 class LSA After summary Cost value calculation method ：

Type 2--- The cost value of the summary network segment is equal to the maximum of all detailed routing cost values plus 1.

Type 1--- The cost value of the summary network segment is equal to the maximum of all detailed routing cost values .

Special area ：

OSPF The special area of can be divided into Two categories: , Four sub categories

Set to The first category Conditions ---

1. You can't yes Backbone area
2. You can't There is Virtual link ;

3, You can't There is ASBR equipment .

We call this area The terminal area （STUB）--- If an area is configured as a terminal area , Then this area will no longer learn 4 Classes and 5 class LSA. In this way The region will refuse to learn the extraterritorial routing information , however , It still has Access extraterritorial routes The needs of , the With , When the configuration is complete , It will automatically generate a line pointing to the backbone area 3 Class default .

[r5-ospf-1-area-0.0.0.2]stub 

--- Configure the end area  

Be careful ： Once you make a special area , Then the equipment in all areas must be made into special areas

2, Completely peripheral area ---totally stub --- Based on the peripheral region , Further refuse to learn 3 class LSA, Keep only 3 Class defaults .

[r1-ospf-1-area-0.0.0.2]stub no-summary

 --- This command Only need ABR The device is configured with that will do .

Set to The second category Conditions ---

1. It can't be the backbone area ;

2, Virtual links cannot exist ;

3, There is ASBR equipment .

We call this area Incomplete ending area （NSSA）--- If a region is configured as an incomplete terminal region , Then this area will Stop learning 4 Classes and 5 class LSA. however , 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 . after , stay 7 class LSA Information leaving NSSA After area , It needs to be converted into 5 class LSA To pass .

Such an area will refuse to learn extraterritorial routing information , however , It still has access to out of domain paths

By the demand , therefore , When the configuration is complete , Meeting Automatically generate a line pointing to the backbone area 7 class

default .

[r4-ospf-1-area-0.0.0.1]nssa

O_NSSA ---7 Class extraterritorial routing information The tag , The default priority is also 150 

E--- commonly Set up 1, On behalf of 5 class LSA. If it's made Special area , be E Bit will be set to 0.

N--- commonly Set up 0,NSSA Area set 1, representative Support 7 class LSA

P --- If Set up 1, On behalf of support 7 turn 5Forwarding Address--- Forwarding address --- A redirection address , Be similar to RIPV2  Next hop field in , When poor route selection occurs , Then the best routing information will be carried in this field , Then it will find the next hop according to the forwarding address , Instead of searching for notifiers according to the algorithm .5 class LSA in , In the absence of poor route selection , Will use 0.0.0.0  To fill in .

however , stay 7 class LSA among , In the absence of poor route selection , Will ASBR Loopback interface of equipment IP Address as forwarding address . For other routers , As long as you can find the loopback interface IP Address , You can find it ASBR equipment . If there is no loopback interface , The of the physical interface will be used IP Address as forwarding address .

Uploading … Re upload cancel

2, Complete and incomplete peripheral regions --- complete NSSA Area ---totally NSSA District

Domain --- stay NSSA On a regional basis , Further refuse to learn 3 class LSA, Generate a 3 

Class defaults .

[r3-ospf-1-area-0.0.0.1]nssa no-summary

Be careful ： Configuration becomes complete NSSA After area , It will automatically generate a three categories that point to the backbone

default , however , Before the ordinary NSSA It's produced by the region 7 Class will remain by default , because

OSPF lSA The priority of the , The device will choose to use 3 Class defaults instead of 7 Class default .

Be careful ： The automatically generated default must be in the same direction as the manually added default , Otherwise, there may be

Current loop .

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 .

OSPF The authentication methods of are divided into 3 Kind of ：

1, Interface authentication -- Configure on the interface of neighbor communication

[r5-GigabitEthernet0/0/0]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 .

[r3-ospf-1-area-0.0.0.0]authentication-mode md5 1 cipher 123456

3, Virtual link authentication --- Add authentication in the virtual link establishment stage . Its essence is also interface authentication .

[r4-ospf-1-area-0.0.0.1]vlink-peer 3.3.3.3 md5 1 cipher 1234562

--- Speed up convergence --- Reduce timer time and modify hello Time

[r5-GigabitEthernet0/0/0]ospf timer hello 5

Be careful ：Hello Time modification , The time of death will be Auto follow 4 Match the multiple relationship and modify the time of death

[r1-GigabitEthernet0/0/0]ospf timer dead 20

Be careful ：dead Time modification ,Hello Time It doesn't change automatically Waitingtime --- Waiting for the timer ---DR and BDR Election time at election , Equal to the time of death , Once the time of death is modified , The waiting time will change synchronously .

POLL --- poll time ---120S --- And the status is down Neighbor relationship sending

hello Packet interval . stay NBMA In the network environment , If One side specifies the neighborhood , Then the state of the neighbor will be changed to the excessive state , The period will follow the default 30S One time transmission Hello package , however , If the other party has not specified , After a waiting time （120S Equal to the time of death ）, The state of the neighbor will be set to down state . after , Will be in accordance with the 120S Send at regular intervals hello package .

[r5-GigabitEthernet0/0/0]ospf timer poll ?

INTEGER<1-3600> Second(s)

Retransmit--- Retransmission time --- Default 5s --- Sending information requires confirmation ,

If no confirmation is received within the retransmission time , Will be retransmitted .

[r5-GigabitEthernet0/0/0]ospf timer retransmit ?

INTEGER<1-3600> Second(s)Transmit Delay

--- Transmission delay ---1s --- This time is attached to LSA Aging time , because LSA During transmission , Time doesn't change , therefore , This time is needed to compensate for the time consumed in the transmission process .

[r5-GigabitEthernet0/0/0]ospf trans-delay 2

3, Silent interface --- Configure an interface as a silent interface , Then this interface will only accept and not send ospf Data packets of

[r5-ospf-1]silent-interface GigabitEthernet 0/0/2

--- stay ospf in , The silent interface will take effect for unicast and multicast packets .4, Default route 3 Class default ,5 Class default ,7 Class default

3 Class default --- Can only Automatically generate through special areas , Common terminal area , End

Whole terminal area , Complete and incomplete peripheral regions

characteristic --- Marked as ospf, The default priority is 10

5 Class default --- The default generated by manual configuration

[r2-ospf-1]default-route-advertise

--- It is equivalent to learning from this device in his way The default route is republished to OSPF In the Internet   characteristic --- Marked as O_ASE, Default The priority for 150

[r2-ospf-1]default-route-advertise always

--- When there is no other network default information on the device , You can issue a mandatory 5 Class default .

7 Class default --- It can be automatically distributed by configuring special areas , You can also issue a manual command 7 Class default

Automatic distribution is in common NSSA In the region .

[r4-ospf-1-area-0.0.0.1]nssa default-route-advertise --- Hand down

Send one 7 Class default information .

5, Route filtering refer to OSPF Targeted at 3 class ,5 Classes and 7 class LSA To filter .[r1-ospf-1-area-0.0.0.2]abr-summary 192.168.0.0 255.255.252.0 not-Advertise

 --- Filter 3 class LSA

[r4-ospf-1]asbr-summary 172.16.0.0 255.255.252.0 not-advertise

 --- Filter 5 class /7 class LSA