Glossary

Review the definitions for terms used across Cloudflare’s Magic Transit documentation.

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Word	Definition
anycast	Anycast is a network addressing and routing method in which incoming requests can be routed to a variety of different locations. Anycast typically routes incoming traffic to the nearest data center with the capacity to process the request efficiently.
equal-cost multi-path routing	A technique that uses hashes calculated from packet data to determine the route chosen.
GRE tunnel	Stands for generic routing encapsulation. It is a protocol wrapping one data packet within another type of data packet. This is useful for enabling protocols that are not normally supported by a network.
Internet Key Exchange (IKE)	The protocol Cloudflare uses to create the IPsec tunnel between Magic WAN and the customer’s device.
IPsec tunnel	Stands for Internet Protocol secure. It is a group of protocols for securing connections between devices, by encrypting IP packets.
letter of agency	Sometimes referred to as a Letter of Authorization. A document that authorizes Cloudflare to advertise your prefixes. This is required to transit providers can accept the routes Cloudflare advertises on your behalf.
maximum segment size (MSS)	MSS limits the size of packets, or small chunks of data, that travel across a network, such as the Internet.
on-ramp	Refers to a way to connect a business network to Cloudflare. Examples of on-ramps, or ways to connect to Cloudflare, are Anycast GRE or IPsec tunnels, Cloudflare Network Interconnect (CNI), Cloudflare Tunnel, and WARP.
prefix	Refers to a number that identifies the network portion of an IP address, and tells devices how many bits are used for a network. For example, `/31`.
static route	A fixed configuration to route traffic through Anycast tunnels from Cloudflare global network to the customer’s locations.
traffic steering	Cloudflare evaluates your route’s health and steers traffic according to priorities defined by you and / or tunnel health.
tunnel health-check	A probe sent by Cloudflare to check for tunnel health. If a tunnel is not considered healthy, Cloudflare reroutes traffic to one that is considered healthy.