What Is Multihoming?

Date First Published: 15th May 2022

Topic: Computer Networking

Subtopic: Data Transmission Technologies

Article Type: Computer Terms & Definitions

Difficulty Level: 6/10

Learn more about what multihoming is in this article.

Multihoming refers to the process of connecting a host to more than one network in order to increase its reliability or performance without compromising its efficiency. Computers are configured with multiple IP addresses and network interfaces. Multihoming is beneficial as system failures are less likely to occur, since there are multiple internet connections rather than a single internet connection. In addition, it helps with load balancing and reduces downtime.

Types Of Multihoming

Four different types of multihoming exist, which include:

Host Multihoming

Host multihoming is when one device is connected to more than one network at the same time. For example:

• A mobile phone is connected to Wi-Fi and a 4G network at the same time.
• A laptop computer is connected to a home network and a VPN at the same time.

Classical Multihoming

A network is connected to several different providers and uses its own range of addresses in classical multihoming. The edge routers of the network connect with the providers through the use of a dynamic routing protocol, usually BGP, that distributes the address range of the network to all providers. 

If one of the links breaks, the dynamic routing protocol detects the failure within a few seconds or minutes and reconfigures its routing tables to use the remaining links. It uses its own range of addresses from a Provider Independent range.

Classical multihoming is expensive since it requires:

• The use of address space that is accepted by all providers.
• A public autonomous system number.
• A dynamic routing protocol.

IPv4 Multihoming

IPv4 multihoming is when two or more ISPs configure a multihomed IPv4 address. Network traffic is automatically rerouted when a link or route fails. However, the disadvantage of IPv4 multihoming is if the central connection point, such as the edge router or shared transmission line went down, the entire network will fail and become unresponsive.

IPv6 Multihoming

IPv6 Multihoming is not yet standardised. This type of multihoming is when two or more ISPs configure a multihomed IPv6 address. A lot of devices are moving to IPv6, or plan to move to IPv6 in the future.