Does linux support dynamic routing?

Concept

Routing: The path for data transmission between two nodes in the network. If the network topology is complex, configuring a dynamic routing protocol can allow the router to automatically learn routes and avoid errors caused by relying solely on the static routing of the gateway.

Router: connects different subnets and forwards data packets between different subnets. Routers equipped with routing protocols can help data packets choose the best transmission path.

Common routing protocols: Distance vector routing protocols, such as RIP protocol, stipulate that the maximum effective number is 15 hops, 16 hops and above are unreachable, and the best path is selected based on which path is the shortest; link Stateful routing protocol, ospf protocol, backbone network AREA0 area is responsible for connecting to other areas. DR and BDR are elected in each area. BDR is the backup of DR. DR and BDR are responsible for maintaining their relationship with neighboring routers; select The best path is based on which path is the fastest.

Main features of static routing

1. Manual configuration

Administrators need to configure manually according to actual needs. The router will not automatically generate it. Static routing includes the IP address of the target node or target network, and can also include the next IP address.

2. The routing path is relatively fixed

The path of the static route manually configured by the administrator on the local router will generally not change unless the administrator modifies it himself.

3. Permanent existence

Once the administrator manually creates a static route, it will be permanently in the routing table, unless the administrator deletes it himself or the outbound interface specified in the static route is closed, or the next The IP address is unreachable.

4. Non-announceability

Static routing information is private by default and will not be advertised to other routers. That is, when a static route is configured on a router, It will not be advertised to other connected routers on the network.

The main features of dynamic routing

1. Adaptive network status changes

Dynamic routing refers to the relationship between routers in the network The process of updating the router table through mutual communication and transfer of routing information. It is implemented based on a certain routing protocol.

2. Automatically maintain routing information

The router can automatically establish its own routing table and make timely adjustments according to changes in actual conditions.

linux dynamic routing configuration

The implementation principle of dynamic routing configuration on Linux

Dynamic routing protocol is a route that automatically updates routes during the route selection process Table information is a protocol that dynamically updates the local routing table based on the status information in each router network. Compared with static routing, it can maintain the routing table more effectively. Common dynamic routing protocols include RIP (Routing Information Protocol), OSPF (Open Short Path First), BGP (Border Gateway Protocol), etc. Their implementation methods are different, and their usage changes with the specific system environment.

Configure dynamic routing

A——r1——r2——B

1. Configure RIP protocol

1) Configure RIP protocol on r1

The first step Install the software

yum  install  quagga   -y

The second step generates the configuration file of the RIP protocol

#cp   /usr/share/doc/quagga-*/ripd.conf.sample        /etc/quagga/ripd.conf    #cd   /etc/quagga      //可以查看下结果

The third step starts the RIP service and quagga service

systemctl   start  zebra    
systemctl   start  ripd

The fourth step checks the service port

netstat   -lantu  |  grep  2601               //zebra       
netstat   -lantu  |  grep  2602               //ripd

Note: The RIP protocol port is UDP 520

The fifth step is to start the virtual terminal and configure the routing protocol

#vtysh
r1#  config  t                   //进入配置模式r1（config）#  router  rip        //进入配置RIP路由协议模式
r1（config-router）#  network   192.168.1.0/24   //声明本机直连的网络段
r1（config-router）#  network   192.168.2.0/24   //声明本机直连网络段
r1（config-router）#  end        //进入全局模式，相当于exit或Ctrl+z
r1#  copy  running-config  startup-config      
//将当前配置保存于在开启读取的配置文件中，可以简写成copy  run   start
r1#  show  ip  route            //查看当前本机路由表
r1#  exit                       //退出vtysh

2) Configure the RIP protocol on r2

The first and fourth steps are the same as the r1 configuration steps

The fifth step is to start the virtual terminal and configure the routing protocol

#vtysh
r2#  config  t                   //进入配置模式r2（config）#  router  rip        //进入配置RIP路由协议模式
r2（config-router）#  network   192.168.2.0/24   //声明本机直连的网络段
r2（config-router）#  network   192.168.3.0/24   //声明本机直连网络段
r2（config-router）#  end        //进入全局模式，相当于exit或Ctrl+z
r2#  copy  running-config  startup-config      
//将当前配置保存于在开启读取的配置文件中，可以简写成copy  run   start
r2#  show  ip  route            //查看当前本机路由表
r2#  exit                       //退出vtysh

2 , Configure ospf protocol

1) Configure ospf protocol on r1

The first step is to install the software

yum  install  quagga   -y      //安装过的话就不用安装了

The second step generates the configuration file of the ospf protocol

#cp   /usr/share/doc/quagga-*/ospfd.conf.sample        
/etc/quagga/ospfd.conf    
#cd   /etc/quagga   //可以过去查看下

The third step starts the ospf service and quagga service

systemctl   start  zebra
systemctl   start  ospfd

The fourth step checks the service port

netstat   -lantu  |  grep  2601               //zebra       
netstat   -lantu  |  grep  2604               //ospf使用的是应用层协议

The fifth step starts Virtual terminal, configure routing protocol

#vtysh
r1#  config  t                    //进入配置模式r1（config）
#  router  ospf        //进入配置ospf路由协议模式
r1（config-router）#  network   192.168.1.0/24  area  10  
//声明本机直连的网络段及隶属区域，area区号只要选择的不是0就行，0是主干网区域
r1（config-router）#  network   192.168.2.0/24  area  10  
//声明本机直连网络段及隶属区域
r1（config-router）#  end        //进入全局模式，相当于exit或Ctrl+z
r1#  copy  running-config  startup-config      
//将当前配置保存于在开启读取的配置文件中，可以简写成copy  run   start
r1#  show  ip  route            //查看当前本机路由表
r1#  exit                       //退出vtysh

2) Configure ospf protocol on r2

The first to fourth steps are the same as the r1 configuration steps

Step 5: Start the virtual terminal and configure the routing protocol

#vtysh
r2#  config  t                     //进入配置模式r2（config）#  router  ospf        //进入配置ospf路由协议模式
r2（config-router）#  network   192.168.2.0/24   
//声明本机直连的网络段及隶属区域，area区号只要选择的不是0就行，0是主干网区域
r2（config-router）#  network   192.168.3.0/24   
//声明本机直连网络段及隶属区域
r2（config-router）#  end        //进入全局模式，相当于exit或Ctrl+z
r2#  copy  running-config  startup-config      
//将当前配置保存于在开启读取的配置文件中，可以简写成copy  run   start
r2#  show  ip  route            //查看当前本机路由表
r2#  exit                       //退出vtysh

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