Cisco Cisco IOS Software Release 12.0(21)S
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Cisco IOS Release 12.0(21)S
GRE Tunneling on Cisco 12000 Series Internet
Routers
Routers
Feature History
This feature module describes the Generic Routing Encapsulation (GRE) Tunneling feature and how it
is implemented in Cisco 12000 series Internet routers. This document includes the following sections:
is implemented in Cisco 12000 series Internet routers. This document includes the following sections:
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Feature Overview
The GRE Tunneling feature allows you to create a virtual point-to-point link to transmit packets between
routers at remote distances over an IP network.
routers at remote distances over an IP network.
GRE Tunneling Protocol
GRE is a standards-based tunneling protocol that can encapsulate a wide variety of protocol packet types
inside IP tunnels, creating a virtual point-to-point link to Cisco routers at remote points over an IP
network. By connecting multiprotocol subnetworks in a single-protocol backbone environment, IP
tunneling using GRE allows network expansion across a single-protocol backbone environment.
inside IP tunnels, creating a virtual point-to-point link to Cisco routers at remote points over an IP
network. By connecting multiprotocol subnetworks in a single-protocol backbone environment, IP
tunneling using GRE allows network expansion across a single-protocol backbone environment.
Release
Modification
12.0(21)S
The GRE Tunneling feature was introduced on Cisco 12000 series Internet
routers.
routers.