HCIA dynamic routing OSPF experiment

Ospf: Open shortest path first protocol  

Classless link state igp agreement ; Cycle update (30min)+ Trigger update ; The update amount of link state protocol increases exponentially with the expansion of network range , therefore ospf The protocol is designed to work in medium and large networks , Need structured deployment - Zoning 、 reasonable ip Address planning ; Multicast update --- 224.0.0.5 224.0.0.6

DR/BDR The election

The condition for neighbors to become adjacency ; Related to network type ;

Network type ：

Point to point -- There can only be two nodes in a network segment  -- Serial link

MA-- Multiple access - There is no limit to the number of nodes in a network segment ; It's not that several nodes are connected at the moment ; Instead, this network type allows multiple nodes to be finally connected ;-- Ethernet

Point to point network neighbor relationship directly becomes adjacency relationship ; stay MA In the network , There will be DR/BDR The election ; In a network segment, only DR/BDR It is adjacent to other routers ; Not DR/BDR They are neighbors ;

Election rules ：

1. First, compare the priority of all the equipment interfaces in the network segment , The bigger the better ;

  The default priority is 1; Value range 0-255,0 The logo does not stand for election

     2. If all candidates have the same priority , Compare the... Of the candidate equipment RID, The value is excellent ;

experiment ：

  The first step is to build a network foundation , Topology design

  Yes 192.168.1.0/24 Divide the subnet

 

next step

To configure OSPF Make an announcement

R1

ospf 1 router-id 1.1.1.1
are 0
network 192.168.1.0 0.0.0.255

R2

ospf 1 router-id 2.2.2.2
are 0
network 192.168.1.0 0.0.0.255

R3

ospf 1 router-id 3.3.3.3
area 0
network 192.168.1.98 0.0.0.0
network 192.168.1.3 0.0.0.0

R4

ospf 1 router-id 4.4.4.4
area 1
network 192.168.1.130 0.0.0.0
ospf 1

Set up R3 by DR equipment

dispaly ospf View yes BDR

  Yes R1 R2 Input

int g0/0/0
ospf dr-priority 0

Look again

  To reach the whole network R4 You need to send the default to other devices

Input

default-route originate

Then look at the routing table , Each router automatically adds a default

  For testing R1pingR4 Default

To ensure the security of update , Encrypt the interface

R1

ospf 1
default-route originate
int g0/0/0
ospf authentication-mode md5 1 cipher 456789

R2

int g0/0/0
ospf authentication-mode md5 1 cipher 456789

 R3

int g0/0/0
ospf authentication-mode md5 1 cipher 456789
int g0/0/1
ospf authentication-mode md5 1 cipher 123456
ospf 1
are 0
abr-summary 192.168.1.0 255.255.255.128

R4

int g0/0/0
ospf authentication-mode md5 1 cipher 123456

The next step is to summarize to reduce the number of routes , Yes R1 R2 R3 Input

ospf 1
are 0
abr-summary 192.168.1.0 255.255.255.128

The last step is to prevent loops , Yes R3 Add an empty interface

ip route-static 192.168.1.0 25 NULL0

End of experiment