Session Control Manager Overview
Features and Functionality - Licensed Enhanced Feature Support â–€
Cisco ASR 5000 Series Product Overview â–„
Figure 152. IPv6 Configuration
Important: The policy interface to PCRF will be IPv6 based when DIAMETER supports IPv6.
Session Recovery Support
The Session Recovery feature provides seamless failover and reconstruction of subscriber session information in the
event of a hardware or software fault within the system preventing a fully connected user session from being
disconnected.
Session recovery is performed by mirroring key software processes (e.g. session manager and AAA manager) within the
system. These mirrored processes remain in an idle state (in standby-mode), wherein they perform no processing, until
they may be needed in the case of a software failure (e.g. a session manager task aborts). The system spawns new
instances of ―standby mode‖ session and AAA managers for each active Control Processor (CP) being used.
Additionally, other key system-level software tasks, such as VPN manager, are performed on a physically separate
Packet Services Card (PSC/PSC2) to ensure that a double software fault (e.g. session manager and VPN manager fails at
same time on same card) cannot occur. The PSC/PSC2 used to host the VPN manager process is in active mode and is
reserved by the operating system for this sole use when session recovery is enabled.
The additional hardware resources required for session recovery include a standby System Management Card (SMC)
and a standby PSC/PSC2.
There are two modes for Session Recovery.
Task recovery mode: Wherein one or more session manager failures occur and are recovered without the need
to use resources on a standby PSC. In this mode, recovery is performed by using the mirrored ―standby-mode‖
session manager task(s) running on active PSCs. The ―standby-mode‖ task is renamed, made active, and is then
populated using information from other tasks such as AAA manager.
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