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How does a GRE tunnel work?
GRE works by encapsulating a payload — that is, an inner packet that needs to be delivered to a destination network — inside an outer IP packet. GRE tunnel endpoints send payloads through GRE tunnels by routing encapsulated packets through intervening IP networks.
How do you characterize GRE tunnel?
What does GRE tunneling mean? Encapsulating packets within other packets is called “tunneling.” GRE tunnels are usually configured between two routers, with each router acting like one end of the tunnel. The routers are set up to send and receive GRE packets directly to each other.
Where is GRE protocol used?
GRE is commonly and only used to transport IPv4 and IPv6 packets. IP packets from the private IP network destined for a host in the private IP network are encapsulated by Router A and forwarded to Router B. Intermediate routers route the packets using addresses in the delivery protocol header.
What is the purpose of GRE tunnel?
Generic routing encapsulation (GRE) provides a private path for transporting packets through an otherwise public network by encapsulating (or tunneling) the packets. GRE tunneling is accomplished through tunnel endpoints that encapsulate or de-encapsulate traffic.
What can affect the state of a GRE tunnel interface?
This document describes the different conditions that can affect the state of a Generic Routing Encapsulation (GRE) tunnel interface. GRE tunnels are designed to be completely stateless. This means that each tunnel endpoint does not keep any information about the state or availability of the remote tunnel endpoint.
How does GRE encapsulate packets within other packets?
Encapsulating packets within other packets is called “tunneling.” GRE tunnels are usually configured between two routers, with each router acting like one end of the tunnel. The routers are set up to send and receive GRE packets directly to each other.
How does GRE Tunneling work on Cloudflare server?
This means that any Cloudflare server can serve as the endpoint for a GRE tunnel using a single IP address, eliminating single points of failure for GRE tunnel connections (Cloudflare also uses this approach to connect Magic WAN customers). To learn more about how Magic Transit works, see our Magic Transit product page.
When to use GRE for IPv4 encapsulation?
The GRE specification has been formalized in RFC 2784 and is commonly used for encapsulating IPv4 and IPv6 packets inside IPv4 packets. RFC 2890 extends RFC 2784 with the edition of key and sequence number.