Cisco Cisco Packet Data Gateway (PDG) Manuale Di Manutenzione
New Feature Summary
Generally Available 06-30-2010
1-16
GGSN Features in Release 9.0
This section provides information for new features for the GGSN Service in Release 9.0.
GRE Protocol Interface
GRE protocol functionality adds one additional protocol on ST-series Multimedia Core
Platforms (ST40 or higher) to support mobile users to connect to their enterprise networks
through Generic Routing Encapsulation (GRE).
Platforms (ST40 or higher) to support mobile users to connect to their enterprise networks
through Generic Routing Encapsulation (GRE).
GRE tunnels can be used by the enterprise customers of a carrier 1) To transport AAA
packets corresponding to an APN over a GRE tunnel to the corporate AAA servers and, 2)
To transport the enterprise subscriber packets over the GRE tunnel to the corporation
gateway.
packets corresponding to an APN over a GRE tunnel to the corporate AAA servers and, 2)
To transport the enterprise subscriber packets over the GRE tunnel to the corporation
gateway.
The corporate servers may have private IP addresses and hence the addresses belonging to
different enterprises may be overlapping. Each enterprise needs to be in a unique virtual
routing domain, known as VRF. To differentiate the tunnels between same set of local and
remote ends, GRE Key will be used as a differentiator.
different enterprises may be overlapping. Each enterprise needs to be in a unique virtual
routing domain, known as VRF. To differentiate the tunnels between same set of local and
remote ends, GRE Key will be used as a differentiator.
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).
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:
●
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.
L2TP, MPLS and IPSEC.
●
Transport protocol-protocol used to carry the encapsulated protocol. The main transport
protocol is IP.
protocol is IP.
The most simplified form of the deployment scenario is shown in the following figure, in
which GGSN has two APNs talking to two corporate networks over GRE tunnels.
which GGSN has two APNs talking to two corporate networks over GRE tunnels.