Cisco ASR 5000 Series User Manual

CDMA2000 Wireless Data Services
▀ Understanding Simple IP and Mobile IP
▄ Cisco ASR 5000 Series Product Overview
OL-22938-02
Following are some of the advantages of reverse tunneling:
All datagrams from the mobile node seem to originate from its home network
The FA can keep track of the HA that the mobile node is registered to and tunnel all datagrams from the mobile
node to its HA
Triangular Routing
Triangular routing is the path followed by a packet from the MN to the Correspondent Node (CN) via the FA. In this
routing scenario, the HA receives all the packets destined to the MN from the CN and redirects them to the MN's care-
of-address by forward tunneling. In this case, the MN sends packets to the FA, which are transported using conventional
IP routing methods.
A key advantage of triangular routing is that reverse tunneling is not required, eliminating the need to encapsulate and
de-capsulate packets a second time during a Mobile IP session since only a forward tunnel exists between the HA and
PDSN/FA.
A disadvantage of using triangular routing is that the HA is unaware of all user traffic for billing purposes. Also, both
the HA and FA are required to be connected to a private network. This can be especially troublesome in large networks,
serving numerous enterprise customers, as each FA would have to be connected to each private network.
The following figure shows an example of how triangular routing is performed.

Cisco ASR 5000 Series Specifications

General

Brand	Cisco
Model	ASR 5000 Series
Category	Network Router
Language	English