|IP over Wireless ATM|
IP over WATM is obtained by combining IPOA and WATM. It is one way to accommodate IP mobile terminals over ATM by relying on the mobility management function of WATM. In other words, the location management function which is needed for the tracking and locating of mobile terminal is provided by WATM. There are various methods for IP over ATM proposed in ATM Forum and IETF.
1. Overlayed IPOA plus WATM
The most straightforward ways to combine IP over ATM and the mobile PNNI/LR schemes is using NHRP(Next Hop Resolution Protocol) for the address resolution phase from IP address to ATM address. Once the ATM address of the mobile terminal obtained by using NHRP, then the mobile PNNI/LR schemes may be used for the locating of the mobile terminal's current location and the setting up a connection. The mobile PNNI/LR schemes are also used for the tracking of the mobile terminals
2. Integrated IPOA plus WATM
Another way is to use integrated routing protocols such as I-PNNI and PAR. I-PNNI and PAR are not address resolution protocols. I-PNNI is arouting protocol used to route SVC reqest and IP layer-3 packets over a network of ATM switches and routers. Switches and routers running I-PNNI behave just like normal PNNI nodes. Thus, all the devices have full knowledge of the heterogeneous topology and use same routin metrices in calculating routes. I-PNNI maps routing metric parameters for IP routing protocols to ATM metrics and vice versa.
3. What are we working on ?
NHRP considers that every terminal are fixed ones, even for a mobile terminal. It registers only its permanent ATM address to the home NHS. Therefore, using NHRP with the mobile PNNI/LR schemes without any modification may be very inefficient. We investigates problems which might happen when existing schemes are naively combined and then we propose a new scheme called "Mobile NHRP" to provide IP service efficiently for the mobile ATM terminals.