Cisco ASR 5000 Series - NPU Fastpath

Serving GPRS Support Node (SGSN) Overview
Features and Functionality - Basic ▀
Cisco ASR 5000 Series Product Overview ▄
OL-22938-02
Condition
Triggered by
SGSN Action
LORC Intimation IE -
private extension payload
Mobile regains coverage
in different SGSN area
MS/SGSN
Send SGSN Context Response
message to new SGSN
Stop counting unsent
packets/bytes
Unsent packet/byte counts
PDP deactivated during
LORC
MS/SGSN
Send DPCQ to GGSN
Stop counting unsent
packets/bytes
Unsent packet/byte counts
PDP deactivated during
LORC
GGSN
Send DPCR to GGSN
Stop counting unsent
packets/bytes
Unsent packet/byte counts
Refer to the SGSN APN Policy Configuration Mode chapter of the Command Line Interface Reference for the command
to configure the GTPC private extension and refer to the IuPS Service Configuratioin Mode chapter of the Command
Line Interface Reference to configure the LORC Cause IE.
NPU FastPath
NPU FastPath‘s proprietary internal direct tunnel optimizes resource usage and reduces latency when processing GTP-U
packets. This proprietary feature is only available on the ASR 5000 SGSN.
Incoming traffic passes through the switch fabric and the routing headers are changed to re-route traffic from the
incoming network processing unit (NPU) of the ingress PSC directly to the outgoing NPU of the egress PSC. This
means that intervening NPUs and CPUs are by-passed. This provides the SGSN with router-like latency and increased
node signaling capacity.