Cisco ASR 5000 series Product Overview page 268

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▀ Understanding Simple IP and Mobile IP

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

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 Product Overview

CDMA2000 Wireless Data Services