Day 7 hcip notes sorting (OSPF configuration)

One 、OSPF The optimization of the

// Home routers rely on the default bearer network segment
1、 Summary : Reduce backbone area LSA The number of （// Each one points to the total server by default ）
2、 Special area ---- Reduce non backbone areas LSA The number of

Summary ：
OSPF The summary of is different from RIP Interface summary , It is called Regional summary , because OSPF Routing information is passed between regions .
classification ：
     1、 Inter domain routing summary （// Pass on 3 class LSA Information , And carry the subnet mask ）----- In essence, it is through ABR Transfer between areas on the device 3 class LSA To summarize

[r1]ospf 1
[r1-ospf-1]area 2
[r1-ospf-1-area-0.0.0.2]abr-summary 192.168.0.0  255.255.252.0

//R1 Summarize the routing information , then R2 I learned R1 One kind of 、 Two category LSA And convert it into summary 3 class LSA, Send to R3 perhaps R4 On

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 （// Pass on 5 class LSA Information , And carry the subnet mask ）----- Its essence 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----ospf In the process

Be careful ：5 class LSA The cost value calculation method after summary ：
type 2 ---- Summarize the cost value of the network segment = Add 1
type 1---- Summarize the cost value of the network segment = The maximum of all detailed routing cost values

Two 、 Special area （ Reduce what you learn LSA Number ）

     OSPF In general, the special areas of can be divided into two categories , Four sub categories 

     1、 Conditions set as the first category ：
          1、 It can't be the backbone area
          2、 Virtual links cannot exist
          3、 Can't exist ASBR equipment
      We call this area The terminal area （STUB）, If an area is configured as a terminal area , Then this area will not be learning 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 , therefore , When the configuration is complete , Will automatically generate a backbone area 3 Class default .

[r5-ospf-1-area-0.0.0.2]stub --- Commands for configuring the end region .

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

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

     2、 Conditions set as the second largest category ：
          1、 It can't be the backbone area
          2、 Virtual links cannot exist
          3、 There is ASBR equipment

      The first 1 Subclass 、 We call this area Incomplete ending area （NSSA）, If a region is configured as an incomplete terminal region , Then this area will not be 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 the need to access extraterritorial routes , therefore , When the configuration is complete , Will automatically generate a backbone area 7 Class default .

[r4-ospf-1-area-0.0.0.1]nssa------- Commands for configuring incomplete end regions .

O_NSSA----7 Class extraterritorial routing information flag ------ The default priority is also 150
E— General arrangement 1, On behalf of 5 class LSA, If you make a special area , General arrangement 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 class LSA Turn into 5 class LSA

     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 supplement . however , stay 7 class LSA in , 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 The address can be found ASBR equipment . If there is no loopback interface , The of the physical interface will be used IP Address as forwarding address .

      The first 2 Subclass ： Complete and incomplete peripheral regions ----- complete NSSA Area ----totally NSSA Area – stay NSSA Further refuse to learn based on the region 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 three types of default that point to the backbone , however . 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 .

3、 ... and 、OSPF Extended configuration

     1、 Manual certification
          a、 Certification is in OSPF In all packets interacting with neighbors , Carry password , If the password is the same, the identity is legal .
          b、 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

[r1-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 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

   [r2-ospf-1-area-0.0.0.0]authentication-mode md5 1 cipher 123456

               3、 Virtual link authentication ---- Virtual link phase adds authentication — Its essence is also interface authentication .

[r4-ospf-1-area-0.0.0.0]vlink-peer 3.3.3.3 md5 1 cipher 123456

[r4-ospf-1-area-0.0.0.0]vlink-peer 3.3.3.3 md5 1 cipher 123456

     2、 Speed up convergence — Reduce timer time （// Change the interface ）—hello The time and the time of death must match , Or we can't connect .

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

Be careful ：hello Time modification , The time of death will become 4 Match the times relationship

  Modify the time of death 
        [r1-GigabitEthernet0/0/0]ospf timer dead 20

Be careful ：dead Time modification ,hello Time does not change automatically

     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 be updated synchronously .

     poll— poll time —120s— And the status is down Neighbor relationship sending hello The interval between packages . 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 . 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 .

[r1-GigabitEthernet0/0/0]ospf timer poll ?
  INTEGER<1-3600>  Second(s)
[r1-GigabitEthernet0/0/0]ospf timer poll

     retransmit ---- Retransmission time ---- Default 5s— Sending information requires confirmation , If no confirmation is received within the retransmission time , Will be retransmitted .

[r1-GigabitEthernet0/0/0]ospf timer retransmit ?
  INTEGER<1-3600>  Second(s)
        

     Transmit Delay----- Transmission delay -----1s---- This time is attached to aging LSA On the time ,LSA During transmission , Time doesn't change , So this time is needed to compensate for the time consumed in transmission .

 [r1-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

 [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 ------ It can only be generated automatically through special areas , Common terminal area , Complete terminal area , Complete incomplete terminal area
                     characteristic ---- Marker bit OSPF, The default priority is 10

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

[r5-ospf-1]default-route-advertise----- It is equivalent to republishing the default route learned in other ways on this device to OSPF In the Internet 
         characteristic ---- Marked as O_ASE, The default priority is 150
 [r5-ospf-1]default-route-advertise always ------ When no other network on the device learns default information , 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 issue a 7 Class default information .

      5、 Route filtering
           refer to OSPF Targeted at 3 class 、5 class 、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