The concept of BGP

The Border Gateway Protocol (BGP) is a distance vector routing Protocol. Different from traditional IGP based on the next hop, BGP is based on AS and is mainly used for the interconnection between ass on the Internet. BGP controls route propagation and path selection. Basically, major network operators in The country use BGP to communicate with their AS numbers.

So for the use of BGP solution to achieve telecom/Unicom/mobile multi-line interconnection of the machine room, we call it BGP room, here, BGP room and single line, double line and three line do a simple difference.

A single line

Single line: that is, the server rented only a bandwidth line access, such as only telecom or Unicom or mobile lines, etc., in the region, we often refer to the Unicom south telecom, that is to say, if the user is concentrated in the north, choose Unicom lines, if concentrated in the south, choose telecom lines. However, if users are distributed all over the country and no region is specified, BGP can be selected to solve the problem of communication between the north and south lines and ensure the access speed of all regions.

Double line

Dual-line: usually is China Telecom + China Unicom dual-line (single network adapter dual IP or double network adapter dual IP), dual-IP dual-line implementation means that two network adapters are installed on a server. Connect the telecom network cable and netcom network cable respectively and set one NETcom IP and one telecom IP, so that one server has two IP addresses. The routing table of netcom or Telecom needs to be added on the server to realize the access of netcom users and telecom users from different lines.

Three lines

Third line: Usually telecom + Unicom + Mobile (single network card with three IP addresses). The public network accesses the public network of telecom, Unicom, and mobile upper-layer operators through the IP addresses of telecom, Unicom, and Mobile respectively. Principle is similar to double line single network card double IP.

The three lines integrate mobile WIFI, and the access rate of mobile WIFI is relatively good. For example, visitors use mobile 4G to access your mobile server. What is the speed experience like? Needless to say, the speed experience will undoubtedly be faster than single-line or dual-line.

AS Autonomous system

An Autonomous system (AS) is a globally unique IP network group that complies with a well-defined routing policy. It identifies and enables aN AS to exchange external routing information between neighboring ass. The value of an AS number ranges from 1 to 65535. 1 64511 is a public AS number registered on the Internet. It is similar to a public IP address and unique in the world and cannot be reused. 64512 to 65535 are private AS numbers. They are similar to private IP addresses. They can be used repeatedly but cannot be seen on the Internet.

Dynamic Routing classification

Routing protocols are divided into Interior Gateway Protocol (IGP) and Exterior Gateway Protocol (EGP), also called intra-domain and inter-domain routing protocols, according to different regions used.

IGP: internal gateway routing protocol, including RIP, OSPF, ISIS, and EIGRP. The IGP routing protocol runs inside aN AS to solve the route selection problem inside an AS. It discovers and calculates routes.

EGP: An external gateway routing protocol, commonly referred to AS BGP, runs between ass and resolves the routing problem between ass. BGP controls the propagation of route entries and selects the optimal route.

In general, IGP is used to calculate and discover routes in the AS, and then BGP is used to transmit the routes generated by IGP to other ass.

The role of BGP

BGP is used to learn routes between ass. The Internet is globally interconnected. In China, Internet operators include China Mobile, China Telecom, and China Unicom. Each company has its own autonomous system and runs the IGP protocol internally. However, the Internet requires interconnection. Therefore, BGP is used to learn the AS internal routes between Telecom and Unicom, enabling telecom and Unicom users to communicate with each other.

For example, the birdie Inner Mongolia node is a BGP line, which does not need to worry about the slow access speed caused by the line nationwide. It can automatically switch when there is a fault, and has the characteristics of redundant backup and loop elimination.

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