Cisco Cisco IOS Software Release 12.4(22)XR

In a session redundancy setup, an accounting ON will be sent by the active unit only when the whole 
setup is brought up (accounting ON will not be sent by the newly active unit after a failover). The standby 
unit does not send any system accounting events under any scenarios. The events, however, are sent in a 
standalone mode.

A sys-off is sent if reload is issued on the active unit.

This section explains new features in Cisco PDSN Release 5.1:

Cisco PDSN provides support for simple IP customers to connect to the L2TP Network Server (LNS) on 
their home network for IP address assignment. The Cisco PDSN watches for the IPCP configuration 
acknowledgement returning from the LNS during PPP negotiation between the MS and the LNS. It then 
extracts the IP address and uses this address, instead of 0.0.0.0 for all subsequent AAA packets.

Simple IP accounting does not support IPv6 addresses that are assigned by the LNS.

A new CLI command, cdma pdsn accounting vpdn address [include renegotiation], is introduced in 
Cisco PDSN Release 5.1. In earlier releases of Cisco PDSN, the accounting-start (with MN IP using all 
zeroes) is sent out as soon as an L2TP tunnel is established. When you enable the cdma pdsn accounting 
vpdn address [include renegotiation] command, the accounting-start is delayed till Cisco PDSN gets 
a valid IP address for the mobile. If the call goes down before the IP address is negotiated, no accounting 
message is sent.

When you enable the CLI command with an extension (including renegotiation), all the packets for 
VPDN are snooped, thus impacting the performance of Cisco PDSN. If the LNS does not change the IP 
address during renegotiation, you can remove the extension of the CLI (including renegotiation). By so 
doing, after the mobile IP address is received, snooping is stopped.