Dscp Marking; Custom Dns Handling; Session Recovery Support - Cisco ASR 5000 Series Administration Manual

Femto Network Gateway Overview
DPD exchanges with the FAPs. However, the FNG always responds to DPD availability checks initiated by a FAP
regardless of the FNG configuration.

DSCP Marking

If different classes of traffic are sent on the same SA and if the FAPs in the network and the FNG are employing the
optional anti-replay feature in the Encapsulating Security Payload (ESP), this could result in inappropriate discarding of
lower priority packets due to the windowing mechanism used by this feature. Therefore, it is recommended that multiple
Child SAs are used to provide the appropriate QoS services. This handling can be applied to different types of traffic
(voice and data) coming from the same UE behind a FAP, or from multiple UEs belonging to the same QoS class. The
FNG will determine the traffic type and provide a QoS treatment based on configured rules.

Custom DNS Handling

The custom DNS feature provides a mechanism whereby the FNG sends the DNS address specified in the FNG
configuration file to the FAP only if the FAP requests it. The FNG considers an address of 0.0.0.0 invalid and does not
include it.

Session Recovery Support

The session recovery feature is a licensed feature on the FNG. It provides seamless failover and nearly instantaneous
reconstruction of subscriber session information in the event of a hardware or software fault within the same chassis,
preventing a fully-connected user session from being dropped. For information about the required software license for
this feature, contact your sales representative.
Session recovery is performed by mirroring key software processes (the IPSec manager, session manager, and AAA
manager, for example) on the FNG. These mirrored processes remain in an idle state (in standby mode), where they
perform no processing until they may be needed in the case of a software failure (a session manager task aborts, for
example). The system spawns new instances of standby mode sessions and AAA managers for each active control
processor being used.
Additionally, other key system-level software tasks such as VPN manager are performed on a physically separate
PSC/PSC2 to ensure that a double software fault (the session manager and the VPN manager fail at same time on same
card, for example) 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.
Important:
OL-24872-01
For more information about session recovery support, refer to the System Administration Guide.
Cisco ASR 5000 Series Femto Network Gateway Administration Guide ▄
Features and Functionality ▀
23