Introduction to static routing and dynamic routing protocols OSPF and rip and static routing configuration commands

- Static routing protocol ：

• Static routing （Static routing） Generally speaking , The network administrator adds the routing table item by item . Even if network conditions have changed or been reconfigured , Static routing will not change . One advantage of static routing is high network security . Dynamic routing requires routers to exchange their routing tables frequently , The analysis of routing table can reveal the network topology and network address information . therefore , For the sake of network security, static routing can also be used . It doesn't take up network bandwidth , Because static routing does not generate update traffic . Static routing is suitable for small and medium-sized networks .

- Dynamic routing protocol ：

- 1、OSPF：

• Open shortest paths take precedence （Open Shortest Path First,OSPF） Protocol is a link state protocol . Each router is responsible for discovering 、 Maintain relationships with neighbors , The known neighbor list and link cost LSU(Link State Update) Message description , Through reliable flooding and autonomous systems AS(Autonomous System) Other routers in the network interact periodically , Learn the network topology of the whole autonomous system ; And inject other information through the router at the boundary of the autonomous system AS Routing information for , To get the whole Internet Routing information for . Every other specific time or when the link state changes , To regenerate the LSA, The router sends the new data through the flooding mechanism LSA(Link-State Advertisement Link status notification ) Announce it , In order to realize the real-time update of routing .OSPF The protocol takes the cost as the measure ：OSPF The protocol is designed , The impact of link bandwidth on routing metrics is considered .OSPF The protocol takes the cost value as the standard , The link overhead is inversely proportional to the link bandwidth , The higher the bandwidth , The smaller the cost ,OSPF The route selection is mainly based on the bandwidth factor .
• OSPF The protocol relies on five different types of packets to establish adjacency and exchange routing information , Greeting Group 、 Database description group 、 Link status request packet 、 Link state update packet and link state confirmation packet .
• • 1、 To greet (Hello) grouping
    OSPF Use Hello Establish and maintain adjacency relationships in groups . Before a router can distribute its neighbor information to other routers , Must first greet its neighbors .
• • 2、 Database description (Data base Description,DBD) grouping
    DBD The grouping does not contain complete “ Link state database ” Information , Contains only a summary of each entry in the database . When a router is first connected to the network , Or just recovered from the failure , It needs to be complete “ Link state database ” Information . here , The router first passes hello Establish two-way communication relationship with neighbors in groups , Then you will receive feedback from each neighbor DBD grouping . The newly connected router will check all profiles , Then send one or more link state request packets , Retrieve the complete entry information .
• • 3、 Link status request (Link State Request,LSR) grouping
    LSR Packets are used to request neighbors to send details of some entries in their link state database . When a router exchanges database description packets with its neighbors , If it is found that some entries in the link state database are missing or expired , Just use LSR Packet to get the newer part of the neighbor link state database .
• • 4、 Link status update (Link State Update,LSU) grouping
    LSU Packets are used to respond to link state request packets , Flooding can also be realized when the link state changes (flooding). In the process of network operation , As long as the link state of a router changes , The router will use LSU, Use the flooding method to update the link status to the whole network .
• • 5、 Link status confirmation (Link State Acknowledgment,LSAck) grouping
    LSAck Packets are used to reply to link state update packets , Confirm it , Thus, the flooding method adopted by the link state update packet becomes reliable .

- 2、RIP：

• Routing information protocol RIP（Routing Information Protocol） It is a routing protocol based on distance vector algorithm , Using the number of jumps as the measurement standard . In bandwidth 、 Low requirements for configuration and management , It is mainly suitable for small-scale networks .

- Huawei and Cisco related configuration commands to be supplemented

• There are two ways to configure static routes ： Static routing with next hop router , And static routing with outgoing interface ：

 Static routing configuration with next hop router ：

router(config)#hostname A （ Change the router host name ）
A(config)#interface f0/0 （ Access interface f0/0）
A(config-if)#ip address 192.168.1.1 255.255.255.0 （ Set interface ip Address and subnet mask ）
A(config-if)#no shutdown （ Enable interface ）
A(config)#interface f0/1
A(config-if)#ip address 192.168.2.1 255.255.255.0
A(config-if)#no shutdown
A(config)#ip route 192.168.3.0 255.255.255.0 192.168.2.2 （ Target segment IP Address   Destination subnet mask next router interface ip Address ）

router(config)#hostname B
B(config)#interface f0/0
B(config-if)#ip address 192.168.3.1 255.255.255.0
B(config-if)#no shutdown
B(config)#interface f0/1
B(config-if)#ip address 192.168.2.2 255.255.255.0
B(config-if)#no shutdown
B(config)#ip route 192.168.1.0 255.255.255.0 192.168.2.1

 Configure static routing configuration with next hop router ：ip route 192.168.3.0 255.255.255.0 192.168.2.2
 It means ： stay HOSTA On , The destination network segment seen by the router is 192.168.3.0 Data packets of , Send the packet to 192.168.2.2 On .
 When there are two or more static routes that point to the same target address but have different exits on the same route or switching device , Traffic sent to the destination address will be load balanced from these outlets .

 Static routing configuration with outgoing interface ：

router(config)#hostname A （ Change the router host name ）
A(config)#interface f0/0 （ Access interface f0/0）
A(config-if)#ip address 192.168.1.1 255.255.255.0 （ Set interface ip Address and subnet mask ）
A(config-if)#no shutdown （ Enable interface ）
A(config)#interface f0/1
A(config-if)#ip address 192.168.2.1 255.255.255.0
A(config-if)#no shutdown
A(config)#ip route 192.168.3.0 255.255.255.0 f0/1（ Target segment IP Address   The destination subnet mask sends out the interface （ Router A））

router(config)#hostname B
B(config)#interface f0/0
B(config-if)#ip address 192.168.3.1 255.255.255.0
B(config-if)#no shutdown
B(config)#interface f0/1
B(config-if)#ip address 192.168.2.2 255.255.255.0
B(config-if)#no shutdown
B(config)#ip route 192.168.1.0 255.255.255.0 f0/1（ Target segment IP Address   The destination subnet mask sends out the interface （ Router B））

 Configure static routing configuration with outgoing interface ：ip route 192.168.3.0 255.255.255.0 f0/1
 It means ： stay HOSTA On , The destination network segment seen by the router is 192.168.3.0 Data packets of , Send the packet to f0/1 On .
 When there are two or more static routes that point to the same target address but have different exits on the same route or switching device , Traffic sent to the destination address will be load balanced from these outlets .

• Generally, we set it to point to IP, That is, static routing with next hop router .