Hcip seventh day notes

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 - 5 LSA

Metric （ cost ） ：5 class LSA Carry the imported extraterritorial routing information through republishing , Because different networks have different evaluation criteria for metrics , So when the extraterritorial route is imported into the local network , We will give up the original cost value , And give him a defined value （ seed-metric Seed measure ）.OSPF The default seed metric in the network is 1

Modify the seed measure when republishing ： [r4-ospf-1]import-route rip 1 cost 10

E Type ： A marker bit , At the marked position 0 when , Represents the use type 1; When marking position 1 when , Then it represents the applicable type 2
———— It refers to the type of cost value ,OSPF The default usage type of the Protocol 2
Modify the cost value type when republishing ：[r4-ospf-1]import-route rip 1 type 1
type 1： If the cost value type is type 1, Then the cost value of all devices in the domain to reach the target network segment outside the domain is equal to the cost value of local arrival notifier plus the seed measurement
type 2： If the cost value type is type 2, Then the cost value of all devices in the domain to reach the target network segment outside the domain is equal to the seed metric

Forwarding 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

Tag ： Routing tags , You can give 5 class LSA Marking , It is convenient to grab the flow through the mark later
Modify the routing mark when republishing ：
[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, Represents when the router VLINK An endpoint of
E ： Set up 1, Represents when the router ASBR equipment
B ： Set up 1, It means that the router is a zone boundary device ABR

OSPF The optimization of the

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 Routing information is passed between regions .
1. Inter domain routing summary ： In essence, it is through 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 learned routing information
2. Extraterritorial routing summary ： In fact, it is in 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 The cost value calculation method after summary ：
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 In general, the special areas of can be divided into two categories , Four sub categories

1. 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. Such an area will refuse to learn extraterritorial routing information , But it still has the need to access extraterritorial routes , So after configuration , It will automatically generate a line pointing to the backbone area 3 Class default Configure the end area ：[r5-ospf-1-area-0.0.0.2]stub Be careful ： Once you make a special area , 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 [ri-ospf-1-area-0.0.0.2]stub no-summary —— This command only needs to be in ABR Just configure it on the device

Conditions set as the second largest category ：

1. We call such a region incomplete terminal region （NSSA）： If a region is configured as an incomplete terminal region , Then this area will no longer learn 4 Classes and 5 class LSA. however , The region still needs to import the following extraterritorial routing information , For refusing 5 class , So we can only 7 class LSA To continue to pass . After the 7 class LSA Information leaving NSSA After area , It needs to be converted into 5 class LSA To pass . Such regions refuse to learn extraterritorial routing information , But it still has the need to access extraterritorial routes , So after configuration , It will automatically generate a line pointing to the backbone area 7 Class default [r4-ospf-1-area-0.0.0.1]nssa O_NSSA :7 Marking of extraterritorial routing information , The default priority is also 150 E ： General arrangement 1, On behalf of 5 class LSA, If it is made into a special area , be E Bit will be set to 0 N ： General arrangement 0,NSSA Area set 1, On behalf of 7 class LSA P ： If you put 1, On behalf of support 7 turn 5 Forwarding Address ： Forwarding address ; A redirection address , Be similar to RIPV2 Next 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 . But in 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 .

2. Complete and incomplete peripheral regions ： complete NSSA Area （totally NSSA Area ）; 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 is called complete NSSA After area , It will automatically generate three types of default that point to the backbone , But before the ordinary NSSA It's produced by the region 7 Class will remain by default , because OSPF ISA 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, a loop may appear

OSPF Extended configuration

1. Manual certification ： Certification is in OSPF Between neighbors , In all packets interacting , Carry password . Password is the same. , Then the identity is legal .
OSPF There are three authentication methods ：
1. Interface authentication ： Configure on the interface of neighbor communication

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

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

2. Speed up convergence ： Reduce timer time
modify hello Time

Waiting time ： 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 Interval of . stay NBMA In the network environment , If one party specifies the neighbor relationship , 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 , But 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 that, according to 120s Send at regular intervals hello package

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

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

4. Default route
3 Class default ,5 Class default ,7 Class default