Cisco ASR 5000 Series, Обзор продукта

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HRPD Serving Gateway Overview
Features and Functionality - Base Software ▀
Cisco ASR 5000 Series Product Overview ▄
OL-22938-02
The HRPD Serving Gateway connects the evolved HRPD access network with the Evolved Packet Core (EPC) as a
trusted non-3GPP access network. In an e-HRPD network the A10'/A11' reference interfaces are functionally equivalent
to the comparable HRPD interfaces. They are used for connection and bearer establishment procedures. In contrast to
the conventional client-based mobility in an HRPD network, mobility management in the e-HRPD application is
network based using Proxy Mobile IPv6 call anchoring between the MAG function on HSGW and LMA on PDN GW.
Connections between the UE and HSGW are based on Simple IPv6. A11' signaling carries the IMSI based user identity.
The main A10' connection (SO59) carries PPP traffic including EAP-over-PPP for network authentication. The UE
performs LCP negotiation with the HSGW over the main A10' connection. The interface between the e-PCF and HSGW
uses GRE encapsulation for A10's. HDLC framing is used on the Main A10 and SO64 auxiliary A10's while SO67 A10
connections use packet based framing. After successful authentication, the HSGW retrieves the QoS profile from the
3GPP HSS and transfers this information via A11' signaling to the e-PCF.
Multiple PDN Support
Enables an APN-based user experience that enables separate connections to be allocated for different services including
IMS, Internet, walled garden services, or offdeck content services.
The MAG function on the HSGW can maintain multiple PDN or APN connections for the same user session. The MAG
runs a single node level Proxy Mobile IPv6 tunnel for all user sessions toward the LMA function of the PDN GW.
When a user wants to establish multiple PDN connections, the MAG brings up the multiple PDN connections over the
same PMIPv6 session to one or more PDN GW LMA's. The PDN GW in turn allocates separate IP addresses (Home
Network Prefixes) for each PDN connection and each one can run one or multiple EPC default & dedicated bearers. To
request the various PDN connections, the MAG includes a common MN-ID and separate Home Network Prefixes,
APN's and a Handover Indication Value equal to one in the PMIPv6 Binding Updates.
Performance: In the current release, each HSGW maintains a limit of up to three PDN connections per user session.
P-GW Selection (Discovery)
Supports the allocation of a P-GW used to provide PDN access to the subscriber. Subscriber information is used via the
STa interface from the 3GPP AAA server, which receives subscriber information from the HSS.
The HSGW uses subscriber information provided by the 3GPP AAA server for P-GW selection. PDN subscription
contexts provided by the 3GPP AAA server may contain:
1.
the IP address of a P-GW
If the 3GPP AAA server provides the IP address of a P-GW, no further P-GW selection functionality is
performed.
2. the identity of a P-GW
If the P-GW identity is a fully qualified domain name (FQDN) instead of an IP address, the P-GW address is
derived by using the Domain Name Service (DNS) function.
3. the identity of an APN
If only an APN is provided, an APN FQDN constructed for the APN is used to derive the P-GW address
through the DNS function. If the DNS function provides a list of P-GW addresses, one P-GW address is
selected from this list using the following criteria:
•
topology matching (if enabled)
•
P-GW priority (as configured in DNS records)