Protocol Architecture
This section illustrates the end-to-end protocol architecture
for the mobile IP and simple IP services. There are some enhancements in the
protocol messages between MSC and BSC for IP services, but the protocol stack
between them is the same as in the CS network (i.e., A1/A2 over SS7), and is not
shown for simplicity. All the control messages at PPP and above layers are user
plane data for the radio link layers.
10.3.1 Simple IP
The control plane for simple IP is illustrated in the Figure 10-2. PPP is used for establishing
link layer connection between MS and PDSN. A11 is a modified version of simple
IPv4 and is used for providing mobility management, charging data collection,
and GRE tunnel management between PDSN and PCF. A11 is transported over UDP as
specified for simple IPv4. A9 is defined to provide mobility management and GRE
tunnel management between PCF and BS. Link access control (LAC) is used between
BS and MS for processing cdma2000 layer 3 signaling messages.
Figure 10-3 shows the
user plane for simple IP protocol architecture. The PPP layer encapsulates and
transfers IP packets between MS and PDSN. A10 and A8 use GRE tunnels to transfer
packets.
10.3.2 Mobile IP
The control plane for mobile IP is shown in Figure 10-4. In the stack shown, IKE is assumed as a key
distribution mechanism between PDSN/FA and HA. Also, IPsec is assumed for both
control and user plane between PDSN/FA and HA. All the protocol layers
underneath the PPP layer stay the same as in simple IP. The main difference from
simple IP is a layer of mobile IP signaling, which is transported over UDP. The
mobile IP layer provides mobility across PDSNs.
The user plane protocol for mobile IP is illustrated in Figure 10-5. The end host (or correspondent
node) sends packets to the MS. The packets arrive at HA and are tunneled to the
PDSN/FA using IP tunnels. The stack under PPP is similar to simple IP, where
packets are carried using GRE tunnels from PDSN to BS.
Sections
