What is BGP4 and BGP4+?

What Is BGP4 and BGP4+?

BGP4 (Border Gateway Protocol version 4) is the protocol that enables the exchange of routing and policy information between border routers in adjacent AS(Autonomous Systems) and within the same AS. This facilitates the global routing of IP datagrams across different networks. Border routers use BGP4 to send update messages, ensuring that reachability information is communicated accurately for efficient data routing.

BGP4+ is an extension of BGP4, the version of the BGP protocol for IPv6 networks, overcoming the limitations of BGP4 and enabling network operators to flexibly manage numerous address types to meet the ever-increasing demand for address space.

The following figure lists the main differences between BGP4 and BGP4+ regarding functionality and features：

How do BGP4 and BGP4+ work?

BGP4 and BGP4+ operate under a unified mechanism. The main difference is that BGP4+ is used in environments with IPv6 networks. The following is an example mainly based on BGP4:

Neighbor Discovery: BGP4 establishes neighbor relationships with other BGP4 routers through manual configuration, ensuring mutual exchange of routing information.

Route Announcement: Each BGP4 router announces its reachable network prefixes and associated path information, providing neighbors with a detailed view of its routing capabilities.

Route Selection: Based on multiple criteria (such as path length, next hop, routing policies, etc.), BGP4 routers evaluate and select the best path to ensure efficiency and reliability in data transmission.

Route Propagation: The selected best path is then communicated to other BGP4 neighbors, updating their routing information to maintain consistency and connectivity across the network.

Session Maintenance: By periodically sending Keepalive messages, BGP4 maintains connections with neighbors and continuously checks the validity of the connection, ensuring stable routing sessions.

Application of BGP4 and BGP4+

BGP4 has many applications in the network. The following are its basic applications:

Internet Routing: BGP4 is the core routing protocol of the Internet, which ensures that packets can be efficiently transmitted between different networks by exchanging routing information between AS(Autonomous Systems).

Inter-domain routing: BGP4 passes routing information between multiple autonomous systems and selects the best path to ensure traffic delivery.

While BGP4 provides basic Internet routing capabilities, BGP4+ expands upon them to accommodate complex network requirements.

Multi-homing: BGP4+ enables network administrators to manage networks with many Internet connections, facilitating traffic control between diverse service providers.

Load balancing: BGP4+ reduces the burden on a single path by dynamically adjusting routing information to uniform distribution of traffic among multiple network paths.

Traffic Engineering: With BGP4+'s traffic engineering capabilities, network operators can choose the best path to route traffic based on real-time network conditions and demand.

Cloud Networking: In modern cloud computing environments, BGP4+ supports efficient communication between virtual machines and other resources, providing the necessary support for multi-cloud and hybrid cloud architectures, enabling seamless collaboration between different cloud environments.