Serving GPRS Support Node (SGSN) Overview
Features and Functionality - Enhanced and Licensed â–€
Cisco ASR 5000 Series Product Overview â–„
Figure 168. trTCM Algorithm Logic for Traffic Policing
yes
green
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yes
no
no
red
yellow
pir
pbs
Tp
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cbs
Tc
account for packet
For commands and information on traffic policing configuration, refer to the Traffic Policing and Shaping and Dynamic
QoS Renegotiation chapter in the System Enhanced Feature Configuration Guide.
Session Recovery
Session recovery provides a seamless failover and reconstruction of subscriber session information in the event of a
hardware or software fault that prevents a fully attached user session from having the PDP contexts removed or the
attachments torn down.
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) 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.
As well, other key system-level software tasks, such as VPN manager, are performed on a physically separate packet
processor card (PSC or PSC2) to ensure that a double software fault (e.g., session manager and VPN manager fail at the
same time on the same card) cannot occur. The PSC 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 and a
standby packet processor card (PSC/PSC2).
There are two modes for Session Recovery.
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