Cisco ASR 5000 Series Administration Manual page 20

▀ Product Description
Figure 1.
E -U T R A N
E P C
e H R P D
The functions of the S-GW for both GTP-based and PMIP-based network sessions include:
packet routing and forwarding.
providing the local mobility anchor point for inter-eNodeB handover and assisting the eNodeB reordering
function by sending one or more "end marker" packets to the source eNodeB immediately after switching the
path.
mobility anchoring for inter-3GPP mobility (terminating the S4 interface from an SGSN and relaying the traffic
between 2G/3G system and a PDN gateway.
packet buffering for ECM-IDLE mode downlink and initiation of network triggered service request procedure.
▄ Cisco ASR 5000 Series Serving Gateway Administration Guide
Basic E-UTRAN/EPC and eHRPD Network Topology
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Serving Gateway Overview
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