Notes....

The end of republishing

effect ： In a network , Such as running multiple routing protocols , Send a routing protocol to another routing protocol

This behavior of two-way republishing , It will cause poor road selection

This situation is called routing feedback ：

Default RIP and OSPF The agreement carries out multipoint （ Bipoint ） Reissue , Because their priorities are different , So the first one ASBR After the re release of the device , Will affect other ASBR Routing table of the device , It makes it possible for the path to be transmitted back to the source protocol , Routing feedback occurs --A Reroute protocol to B After the agreement , Sent back again B agreement ---- Poor routing will occur when the route feedback is light , In the most serious case, ring generation will occur

R1--R2--R3--R4--R1

The worst case will be the loop

Solve the situation

Change priority --- The priority of the imported routing information outside the domain is increased （ The default priority is 150）, The routing feedback is avoided -- So change the priority to 150, Greater than all Huawei defined IGP Default priority of the Protocol --- And define OSPF The priority of internally generated routes is defined as 10-- In this way, route feedback is eliminated

Due to the problem of seed measurement of republishing Technology , It will inevitably lead to poor route selection , Only the routing strategy can be considered as interference in routing .

Control layer flow -- The routing protocol transmits the traffic generated by the routing information

Data layer traffic -- The traffic generated when the device accesses the target network segment

Control layer flow --- data IP Address masked ---ACL List crawl can only crawl this network segment , Can't see the mask

192.168.1.0/24 --ACL List can only catch 192.168.1.0 Can't catch the back /24

Routing strategy ： In the process of controlling the flow of the layer , Intercept flow , Then modify the traffic to forward or not forward , The final implementation affects the generation of router routing table , The effect of interference in route selection --ip a key - Route control

Follow ACL The list is similar , But the routing list is to realize the generation of routing table

1. Grab traffic

1.ACL list -- Grasp the data layer traffic -- Therefore, because of the existence of wildcards, you can flexibly match digital features , But there is no way to match the mask features in the routing information , So I'm not good at capturing traffic in the control layer

2.IP-prefix（ The prefix list ）-- Specially grab the control layer traffic -- You can match the mask

No more creating lists , Just use it directly inside the list

aa（ Name of the custom prefix list ）premit（ Allow and deny , If only crawl traffic is allowed, you can select permit）192.168.1.0 24--- Control the information of the target network in the captured control layer traffic

View the information of prefix list

The serial number here （index） Gradually add 5-- And ACL The matching principle of --

Matching rules for prefix list ： From top to bottom , One by one matching --- Once it is matched, the action will be executed according to the corresponding rules, instead of matching downward , The end implicitly rejects all rules

The rule in the prefix list defaults to 10 Automatically add a sequence number to the step , To insert and delete rules

2. Routing strategy

3.route-policy -- Routing strategy

3. Call the routing policy during republishing