Configuring Generic Routing Encapsulation; Understanding Generic Routing Encapsulation On Acx Series; Overview Of Gre - Juniper ACX1000 Configuration Manual

CHAPTER 19

Configuring Generic Routing Encapsulation

Understanding Generic Routing Encapsulation on ACX Series

Overview of GRE

Copyright © 2017, Juniper Networks, Inc.
Understanding Generic Routing Encapsulation on ACX Series on page 581
Configuring Generic Routing Encapsulation Tunneling on ACX Series on page 584
Configuring Unicast Tunnels on page 585
Generic routing encapsulation (GRE) provides a private, secure path for transporting
packets through an otherwise public network by encapsulating (or tunneling) the packets.
This topic describes:
Overview of GRE on page 581
GRE Tunneling on page 582
Configuration Limitations on page 583
GRE encapsulates data packets and redirects them to a device that de-encapsulates
them and routes them to their final destination. This allows the source and destination
routers to operate as if they have a virtual point-to-point connection with each other
(because the outer header applied by GRE is transparent to the encapsulated payload
packet). For example, GRE tunnels allow routing protocols such as RIP and OSPF to
forward data packets from one router to another router across the Internet. In addition,
GRE tunnels can encapsulate multicast data streams for transmission over the Internet.
GRE is described in RFC 2784 (obsoletes earlier RFCs 1701 and 1702). The routers support
RFC 2784, but not completely. (For a list of limitations, see
on page 583.)
As a tunnel source router, the router encapsulates a payload packet for transport through
the tunnel to a destination network. The payload packet is first encapsulated in a GRE
packet, and then the GRE packet is encapsulated in a delivery protocol. The router
performing the role of a tunnel remote router extracts the tunneled packet and forwards
the packet to its destination.
"Configuration Limitations"
581