MBGP (Multi Protocol BGP)

Last updated on Apr 26, 2023

Border Gateway Protocol (BGP) is an internet protocol that is used to exchange routing information between different networks. It is the protocol used by Internet Service Providers (ISPs) to connect their networks to each other and to the internet backbone. BGP is responsible for making sure that traffic is routed efficiently between different networks, and that any network outages are quickly detected and handled.

Multi Protocol BGP (MBGP) is an extension of BGP that allows it to carry routing information for multiple protocols, including IPv4, IPv6, and other network-layer protocols. This makes it possible for BGP to be used in a wider range of networking scenarios, such as for connecting different types of networks together, and for supporting more advanced routing features.

In this article, we will take a closer look at Multi Protocol BGP (MBGP), including its features, advantages, and use cases.

BGP Overview

Before diving into MBGP, let's first briefly review BGP. BGP is a routing protocol used to exchange routing information between different networks. Each network that participates in BGP is known as an Autonomous System (AS), and is identified by a unique number called an AS number. BGP is used to exchange routing information between different ASes, which allows traffic to be routed between them.

BGP is a path-vector protocol, which means that it uses a set of rules to determine the best path for routing traffic between two networks. BGP considers factors such as the number of AS hops between networks, the bandwidth of the links between them, and other metrics to determine the best path.

One of the key features of BGP is its ability to detect network outages and to quickly reroute traffic around them. BGP accomplishes this by using a system of advertisements called routes, which specify the paths that traffic should take between different networks. When a network outage occurs, BGP can quickly detect it and remove the affected routes from its routing table, which ensures that traffic is rerouted around the outage.

Multi Protocol BGP (MBGP) Overview

MBGP is defined in RFC 4760, which was published in 2007. The key difference between MBGP and traditional BGP is that MBGP can carry routing information for multiple network-layer protocols, whereas traditional BGP only supports IPv4. MBGP achieves this by adding support for multiple address families to BGP, which allows it to exchange routing information for different protocols.

In MBGP, each address family is identified by a unique address family identifier (AFI) and a subsequent address family identifier (SAFI). The AFI identifies the type of network-layer protocol being used, such as IPv4 or IPv6, while the SAFI identifies the type of routing information being carried, such as unicast or multicast.

MBGP Features and Advantages

There are several key features and advantages of MBGP that make it a valuable tool for network operators:

Support for Multiple Network-Layer Protocols: One of the main advantages of MBGP is that it can support multiple network-layer protocols, such as IPv4, IPv6, and other protocols. This makes it possible to use BGP in a wider range of networking scenarios, such as for connecting different types of networks together, and for supporting more advanced routing features.
Separation of Routing Information: MBGP supports the separation of routing information for different protocols, which makes it possible to route traffic differently depending on the type of traffic being carried. For example, network operators can use different routing policies for IPv4 and IPv6 traffic, which allows them to optimize traffic routing for each protocol.
Hierarchical Route Distribution: MBGP supports hierarchical route distribution, which allows networks to be organized into a hierarchy of regions and sub-regions. This makes it possible to distribute routing information more efficiently, since routing updates only need to be sent to the regions that need them.
Scalability: MBGP is designed to be highly scalable, which makes it suitable for use in large networks with many different ASes. The use of hierarchical route distribution and the separation of routing information for different protocols helps to reduce the amount of routing information that needs to be exchanged between ASes.
Flexibility: MBGP is a flexible protocol that can be used in a wide range of networking scenarios. It can be used to connect different types of networks together, such as public and private networks, and it can be used to support a wide range of routing features, such as load balancing and traffic engineering.
Security: MBGP includes several security features that help to ensure the integrity and authenticity of routing information. These features include the use of digital signatures and message authentication codes (MACs) to protect routing updates from being tampered with.

MBGP Use Cases

MBGP is used in a wide range of networking scenarios, including:

Connecting Different Types of Networks: MBGP is often used to connect different types of networks together, such as public and private networks. For example, an organization might use MBGP to connect its internal network to the internet, or to connect multiple data centers together.
Supporting IPv6: MBGP is used to support IPv6 routing, since traditional BGP only supports IPv4. MBGP allows network operators to exchange routing information for both IPv4 and IPv6 networks.
Traffic Engineering: MBGP can be used to support traffic engineering, which involves the optimization of traffic routing to improve network performance. By using MBGP, network operators can specify different routing policies for different types of traffic, which allows them to optimize traffic routing based on factors such as bandwidth, latency, and cost.
Load Balancing: MBGP can be used to support load balancing, which involves distributing traffic across multiple network paths to improve performance and reliability. By using MBGP, network operators can specify different routes for different types of traffic, which allows them to distribute traffic more efficiently.

Conclusion

Multi Protocol BGP (MBGP) is an extension of BGP that allows it to carry routing information for multiple protocols, including IPv4, IPv6, and other network-layer protocols. MBGP is a flexible and scalable protocol that can be used in a wide range of networking scenarios, and it includes several features and advantages that make it a valuable tool for network operators. MBGP is used to connect different types of networks together, to support IPv6 routing, to enable traffic engineering and load balancing, and more.