Cisco Cisco Packet Data Interworking Function (PDIF) Notas De La Versión
S-GW Changes in Release 15.0
▀ S-GW Enhancements for September 30, 2013
▄ Cisco ASR 5x00 Release Change Reference
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LIPA Support
A LIPA (Local IP Access) PDN is a PDN Connection for local IP access for a UE connected to a HeNB. The LIPA
architecture includes a Local Gateway (LGW) acting as an S-GW GTPv2 peer. The LGW is collocated with HeNB in
the operator network behaves as a PGW from SGW perspective. Once the default bearer for the LIPA PDN is
established, then data flows directly to the LGW and from there into the local network without traversing the core
network of the network operator.
architecture includes a Local Gateway (LGW) acting as an S-GW GTPv2 peer. The LGW is collocated with HeNB in
the operator network behaves as a PGW from SGW perspective. Once the default bearer for the LIPA PDN is
established, then data flows directly to the LGW and from there into the local network without traversing the core
network of the network operator.
In order to support millions of LIPA GTPC peers, S-GW memory management has been enhanced with regards to
GTPv2 procedures and as well as to support the maintenance of statistics per peer node.
GTPv2 procedures and as well as to support the maintenance of statistics per peer node.
Establishment of LIPA PDN follows a normal call flow similar to that of a normal PDN as per 23.401; the specification
does not distinguish between a LGW and a PGW call. As a result, the S-GW supports a new configuration option to
detect a LIPA peer. As a fallback mechanism, heuristic detection of LIPA peer based on data flow characteristics of a
LIPA call is also supported.
does not distinguish between a LGW and a PGW call. As a result, the S-GW supports a new configuration option to
detect a LIPA peer. As a fallback mechanism, heuristic detection of LIPA peer based on data flow characteristics of a
LIPA call is also supported.
Whenever a peer is detected as a LIPA peer, the S-GW will disable GTPC echo mechanism towards that particular peer
and stop maintaining some statistics for that peer.
and stop maintaining some statistics for that peer.
A configuration option in APN profile explicitly indicates that all the PDN’s for that APN are LIPA PDN’s, so all
GTPC peers on S5 for that APN are treated as LGW, and thus no any detection algorithm is applied to detect LGW.
GTPC peers on S5 for that APN are treated as LGW, and thus no any detection algorithm is applied to detect LGW.
Node Functionality GTP Echo
This feature helps exchange capabilities of two communicating GTP nodes, and uses the new feature based on whether
it is supported by the other node.
it is supported by the other node.
This feature allows S-GW to exchange its capabilities (MABR, P-GW Restart Notification, NTSR) with the peer entities
through ECHO messages. By this, if both the peer nodes support some common features, then they can make use of new
messages to communicate with each other.
through ECHO messages. By this, if both the peer nodes support some common features, then they can make use of new
messages to communicate with each other.
With new “node features” IE support in ECHO request/response message, each node can send its supported features
(MABR, P-GW Restart Notification, NTSR). This way, S-GW can learn the peer node’s supported features. S-GW’s
supported features can be configured by having some configuration at the service level.
(MABR, P-GW Restart Notification, NTSR). This way, S-GW can learn the peer node’s supported features. S-GW’s
supported features can be configured by having some configuration at the service level.
If S-GW wants to use new message, such as P-GW Restart Notification, then S-GW should check if the peer node
supports this new feature or not. If the peer does not support it, then S-GW should fall back to old behavior.
supports this new feature or not. If the peer does not support it, then S-GW should fall back to old behavior.
If S-GW receives a new message from the peer node, and if S-GW does not support this new message, then S-GW
should ignore it. If S-GW supports the particular feature, then it should handle the new message as per the specification.
should ignore it. If S-GW supports the particular feature, then it should handle the new message as per the specification.
Overcharging Protection Support
Overcharging Protection helps in avoiding charging the subscribers for dropped downlink packets while the UE is in
idle mode. In some countries, it is a regulatory requirement to avoid such overcharging, so it becomes a mandatory
feature for operators in such countries. Overall, this feature helps ensure subscriber are not overcharged while the
subscriber is in idle mode.
idle mode. In some countries, it is a regulatory requirement to avoid such overcharging, so it becomes a mandatory
feature for operators in such countries. Overall, this feature helps ensure subscriber are not overcharged while the
subscriber is in idle mode.
Important:
Use of Overcharging Protection in S-GW requires that a valid license key be installed. Contact your
Cisco account representative for information on how to obtain a license.
P-GW will never be aware of UE state (idle or connected mode). Charging for downlink data is applicable at P-GW,
even when UE is in idle mode. Downlink data for UE may be dropped at S-GW when UE is in idle mode due to buffer
overflow or delay in paging. Thus, P-GW will charge the subscriber for the dropped packets, which isn’t desired. To
address this problem, with Overcharging Protection feature enabled, S-GW will inform P-GW to stop or resume
charging based on packets dropped at S-GW and transition of UE from idle to active state.
even when UE is in idle mode. Downlink data for UE may be dropped at S-GW when UE is in idle mode due to buffer
overflow or delay in paging. Thus, P-GW will charge the subscriber for the dropped packets, which isn’t desired. To
address this problem, with Overcharging Protection feature enabled, S-GW will inform P-GW to stop or resume
charging based on packets dropped at S-GW and transition of UE from idle to active state.