Router protocols and IP addresses

With the development of China's routing industry, it also promotes the improvement of router protocols. The TCP/IP-based Internet has gradually developed into a super-large computer network with the largest number of users and the largest resources in the world. Therefore, TCP/IP has become a de facto industrial standard. IP networks are gradually becoming the mainstream of modern and future computer networks. An IP network is composed of IP subnets connected by routing devices. These routing devices are responsible for finding routes between IP subnets and forwarding IP groups to the next IP subnet.
 
IP address

An IP address is the basis for data transmission in an IP network. It identifies a connection in an IP network. A host can have multiple IP addresses. The IP addresses in the IP Group remain unchanged during network transmission.

1. Basic address format

The current IP address uses a 32-bit address, represented in dotted decimal format, for example, 172.16.0.0. The address format is: IP address = network address + host address or IP address = Host address + subnet address + host address. The network address is uniformly allocated by the Internet authority InterNIC to ensure the global uniqueness of the network address. The host address is assigned by the system administrator of each network. Therefore, the uniqueness of the network address and the host address in the network ensure the global uniqueness of the IP address.

2. Reserved Address Allocation

IP addresses can be divided into public addresses and private addresses based on their purposes and security levels. Public addresses are used in the Internet and can be accessed freely on the Internet. Private addresses can only be used in internal networks and can communicate with the Internet only through proxy servers. Networks with reserved addresses can only communicate internally, but cannot communicate with other networks. Because the reserved addresses in the Network may also be used by other networks, if the network is connected, the problem may occur because the address is not unique when looking for a route. However, these networks that use reserved addresses can interconnect with external networks by translating the reserved addresses in the network into public addresses. This is also an important way to ensure network security.
 
Classless Inter-Domain Routing (CIDR)

As the number of hosts connected to the Internet doubles every year, the Internet is faced with crises such as a shortage of Class B addresses, route table explosion, and exhaustion of the entire address. Classless Inter-Domain Routing (CIDR) is a direct solution developed to solve these problems. It gives the Internet enough time to wait for the generation of the next-generation Router Protocol. According to the CIDR policy, you can apply for several Class C addresses instead of applying for a separate class B address to solve the problem of lack of Class B addresses. The assigned Class C addresses are not random, but continuous. They have the same highest bit, that is, they have the same prefix. Therefore, the route table only needs one table item to represent a group of network addresses, this method is called "route table clustering ". In addition to the "route table clustering", each ISP can obtain an address space from InterNIC and then allocate these addresses to users. A directly connected route is automatically generated after the IP address of the router network interface is configured. Therefore, if no special restrictions are imposed on these interfaces, these router protocols forward data based on the route.

Route Selection technology

The route selection in the IP network is completed by the routing device. A vro executes a certain vro protocol to find the optimal route to the destination host or network for IP datagram, and forwards the datagram to achieve route selection.
 
1. There are two types of routing protocols

Router Protocol Routing Protocol) this type of Protocol uses certain Routing algorithms to find the optimal path to the target host or network, such as the RIP Routing information Protocol. Router Protocol (Routed Protocol) this type of Protocol transmits data packets along the selected path. For example, you can use the IP Protocol to convert a physical connection to a network connection to achieve the main function of the network layer-routing.

2. Direct Connection and non-direct connection
 
The network directly connected to each network interface of the router uses a direct connection route for communication. There are two types of routes in a vro: directly connected routes and non-directly connected routes. Directly Connected Networks of interfaces can communicate with each other. Communication between two or more vrouters uses a non-direct connection route. A non-direct connection route is a static route manually configured or a dynamic route obtained by running the Router Protocol. Static Routing is more operable and secure than dynamic routing. IP networks have gradually become the standard of modern networks. When using the Router Protocol to build a network, you must use a routing device to interconnect IP subnets and use routing mechanisms between IP subnets, establish a hierarchical Internet through IP Gateway interconnection.