Cisco Cisco Mobility Unified Reporting User Guide
GGSN Support in GPRS/UMTS Wireless Data Services
▀ Features and Functionality - Optional Enhanced Feature Software
▄ Cisco ASR 5000 Series Product Overview
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GRE Tunneling is a common technique to enable multi-protocol local networks over a single-protocol backbone, to
connect non-contiguous networks and allow virtual private networks across WANs. This mechanism encapsulates data
packets from one protocol inside a different protocol and transports the data packets unchanged across a foreign
network. It is important to note that GRE tunneling does not provide security to the encapsulated protocol, as there is no
encryption involved (like IPSEC offers, for example).
GRE Tunneling consists of three main components:
connect non-contiguous networks and allow virtual private networks across WANs. This mechanism encapsulates data
packets from one protocol inside a different protocol and transports the data packets unchanged across a foreign
network. It is important to note that GRE tunneling does not provide security to the encapsulated protocol, as there is no
encryption involved (like IPSEC offers, for example).
GRE Tunneling consists of three main components:
Passenger protocol-protocol being encapsulated. For example: CLNS, IPv4 and IPv6.
Carrier protocol-protocol that does the encapsulating. For example: GRE, IP-in-IP, L2TP, MPLS and IPSEC.
Transport protocol-protocol used to carry the encapsulated protocol. The main transport protocol is IP.
The most simplified form of the deployment scenario is shown in the following figure, in which GGSN h as two APNs
talking to two corporate networks over GRE tunnels.
The following figure shows a high-level overview of the GRE deployment scenario:
talking to two corporate networks over GRE tunnels.
The following figure shows a high-level overview of the GRE deployment scenario: