ZXUN xgw Product Description (vgw)

Transcription

1 ZXUN xgw Product Description (vgw)

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3 ZXUN xgw Product Description (vgw) Version Date Author Reviewer Notes V /6/30 CN Product Line CN Planning Dept 2016 ZTE Corporation. All rights reserved. ZTE CONFIDENTIAL: This document contains proprietary information of ZTE and is not to be disclosed or used without the prior written permission of ZTE. Due to update and improvement of ZTE products and technologies, information in this document is subjected to change without notice. ZTE Confidential & Proprietary 1

4 TABLE OF CONTENTS 1 Overview Location of ZXUN xgw in EPS network Interfaces and Protocols of ZXUN vgw Highlight Features Operational Benefits Performance Optimization Techniques Cost Benefits Single Network Element for GSM/EDGE/UMTS/LTE Open interface and Flexible Networking Capabilities High Reliability Fast Deployment Elastic Scalability Abundant Service Functions Smooth Expansion Capabilities Convenient Operation Maintenance Functionality Session Management GTP Management Direct Tunnel (DT) IP Address Management Routing APN VPN Radius Client Security QoS Service Awareness and DPI Policy Control Charging IPv SGW and PGW Combination Capacity Sharing between 2G/3G/LTE Network Data Collection and Reporting Other Service and Function System Architecture Hardware ZTE Confidential & Proprietary

5 4.2 CMS and Hypervisor Software Architecture ZXUN vgw VM Deployment Technical Specifications Interface Indices Capacity Indices Operation and Maintenance Configuration Management System Alarm Management System Performance Management System Diagnosis Test system Signaling Tracing System Service Observation System Variable Management System Reliability Design MTBF and MTTR analysis Reliability Analysis Physical Failure Recovery Hypervisor Failure Recovery VM Failure takeover Networking Acronyms and Abbreviations ZTE Confidential & Proprietary 3

6 FIGURES Figure 1-1 Location of ZXUN vgw in EPS Supporting 3GPP Access... 5 Figure 2-1 vgw Deployment Time vs. Legacy Deployment Time... 8 Figure 2-2 Cost Comparison of Legacy EPC and vepc... 9 Figure 3-1 Gn/Gp SGSN DT Architecture...16 Figure 3-4 Separated Traffic Architecture by VRF...20 Figure 3-5 E2E QoS Architecture...23 Figure 3-6 DNS-based Service Identification Flow...24 Figure 3-7 E2E IPv6 Architecture...30 Figure 4-1 Layered Structure of vgw Software System...37 Figure 4-2 SAE-GW/GGSN VNF Architecture and Components...38 Figure 6-1 O&M System Structure...42 Figure 7-1 NFV Reliability Model...48 Figure 7-2 Availability vs Silent Error vs Server Availability - Single Backup...50 Figure 7-3 Availability vs Silent Error vs Server Availability - Dual Backup...52 Figure 8-1 PS/EPS Backbone Network...57 Figure 8-2 Networking Mode of vgw and MME that are in Same LAN...58 TABLES Table 1-1 Related Interfaces and Protocols of ZXUN vgw for 3GPP Function... 6 Table 4-1 Module/component supported by NFV SAE-GW/GGSN...39 Table 5-1 ZXUN vgw Interface Standards and Cables...41 Table 5-2 ZXUN vgw Capacity Indices...41 Table 9-1 Acronyms and Abbreviations ZTE Confidential & Proprietary

7 1 Overview 1.1 Location of ZXUN xgw in EPS network Integration of core network and access agnostic are the trends of mobile network. Following these trends, ZTE provides an integrated core network gateway product, ZXUN vgw (extendable Gateway), which supports 2G, 3G, LTE and non-3gpp access. ZXUN vgw could be deployed as GGSN, Serving-GW, PDN-GW, PDSN, HA and GGSN/Serving-GW/PDN-GW combo node to satisfy different network scenarios during the evolution to pure LTE/EPC network. Acting as Serving-GW/PDN-GW combo node (SAE-GW), ZXUN xgw connects E-UTRAN to external data network for allowing external network access to subscribers; serving as Serving-GW (SGW), it connects with E-UTRAN and PDN GW (PGW); deploying as PDN-GW, it connects Serving-GW to external data network. Deploying as GGSN in existing GPRS/UMTS PS network, ZXUN xgw connects PS backbone network to external data network. Deploying as PDSN in existing CDMA/EVDO network, ZXUN xgw connects the CDMA/EVDO network to external data network. Deploying as MIP HA in CDMA/EVDO and WiMAX, ZXUN xgw supports seamless mobility between different networks. The vgw-gtp is one of main service processing modules in xgw subsystem, responsible for establishing bearer channels between the S1/S5 (GTP based)/gn interfaces, transmitting data on the EPS backbone network and routing and transferring them to external PDN networks for GPRS, UMTS and LTE network. By service features, GTP has two parts: GTP-C and GTP-U. GTP_C processes signaling of all the signaling planes at the S5 (GTP based)/s11/gn interfaces, and is responsible for establishing, updating and deleting the GTP tunnels and triggering reverse PDP activation. GTP_U is responsible for fast routing and forwarding data at the S1/S5 (GTP based)/gn interfaces. The position of ZXUN vgw in the EPS systems is shown in the following figure. Figure 1-1 Location of ZXUN vgw in EPS Supporting 3GPP Access ZTE Confidential & Proprietary 5

8 PDN PCRF Gx OCS Gy HLR Gr Gi GGSN Gi AAA Ga Gn CG Ga SGSN ZXUN xgw AAA OCS Gn Gn SGi SGi Gy Ga CG Gx PGW SGW PCRF S5 S11 MME HSS S6a MME S10 Gb Iu-PS S1-U S1-MME BTS GSM BSC Abis BTS Um NodeB UMTS RNC Iub NodeB Uu enodeb LTE X2 enodeb LTE-Uu 1.2 Interfaces and Protocols of ZXUN vgw ZXUN vgw adopts a modular distributed processing structure and executes different functions through different modules. With different combinations of modules, ZXUN vgw conducts the establishment and maintenance of the LTE GTP tunnel and routing and forwarding of data between the EPS backbone network and external PDNs. ZXUN vgw also integrates such functions as RADIUS authentication, dynamic address allocation of DHCP, establishment of VPN tunnel, online charging, offline charging, etc. The related interfaces, protocols and functions of the ZXUN vgw are listed in following table. Table 1-1 Related Interfaces and Protocols of ZXUN vgw for 3GPP Function Interworking NE Interface Name Protocol Interface function GGSN - Gn/Gp SGSN Gn GTPv0/v1 Transmitting GTP signaling/data GGSN - PCRF Gx Diameter Transfer of (QoS) policy and 6 ZTE Confidential & Proprietary

9 Interworking NE Interface Name Protocol Interface function charging rules GGSN - OCS Gy Diameter Online Charging GGSN - CG Ga GTP Offline Charging GGSN - Internet Gi IP GGSN - AAA Gi Radius Forwarding data to the external network Authentication, Authorization, and Accounting SGW - MME S11 GTPv2 Transmitting GTP signaling SGW - E-UTRAN S1-U GTP-U Transmitting GTP data SGW - PGW S5/S8 GTPv2 Implementing mobility management and transmitting package between SGW and PGW. PGW - Gn/Gp SGSN Gn/Gp GTPv1 Transmitting GTP signaling/data PGW - PCRF Gx Diameter Transfer of (QoS) policy and charging rules PGW - OCS Gy Diameter Online Charging SGW/PGW - CG Ga GTP Offline Charging PGW - Internet SGi IP PGW - AAA SGi Radius Forwarding data to the external network Authentication, Authorization, and Accounting ZTE Confidential & Proprietary 7

10 2 Highlight Features 2.1 Operational Benefits We use the following diagram to illustrate the operational benefits of vgw. The diagram compares the typical deployment time (in days) between vgw and legacy network elements. In summary, vgw reduces the typical deployment time from 91 days to 19 days. Figure 2-1 vgw Deployment Time vs. Legacy Deployment Time vgw Deployment Period Against NF(Day) Planning Purchase HW Installation SW Installation 14 Service Config Test Total Period Traditional Deployment vgw Deployment 2.2 Performance Optimization Techniques Performance, especially the media plane performance using COTS has always been a concern for service providers and equipment vendors alike. ZTE s vepc address the issue by applying the following performance optimization techniques to the media plane software processing module - packet forwarding unit (PFU). Combine the Single Root I/O Virtualization (SR-IOV) with Intel s Data Plane Development Kit (DPDK) techniques to enhance the performance. Apply Open vswitch (OVS) on enhanced Intel s DPDK (By ZTE) to further enhance the media processing performance. 8 ZTE Confidential & Proprietary

11 In addition, by replacing the regular network interface card (NIC) with ZTE s smart NIC, the performance can be further enhanced. With the performance optimization techniques discussed above, we are able to enhance the media plane performance by 4 ~ 5 times. 2.3 Cost Benefits It s intuitive that with its hardware resource being shared among different network elements, virtualization may require less hardware, such as number of CPUs or server blades under the same network traffic condition. ZTE quantifies this by comparing the cost required for ZTE s vgw and the legacy solution. The following figure illustrates the measurement results. This clearly illustrates the CAPEX cost benefits that ZTE s vgw provides. Figure 2-2 Cost Comparison of Legacy EPC and vepc The above equipment cost includes xgw & vgw nodes and networking switches. And analyze costs with the example of a typical capacity (2 million PDP and 100Gbps throughput). Through Cost Comparison, it can be concluded that: The vgw with ZTE COTS server has the lowest cost. ZTE Confidential & Proprietary 9

12 vgw Network switch cost rises slightly due to vgw introduces data center network feature. Commercial virtualization SW has certain proportion in total vgw costs. 2.4 Single Network Element for GSM/EDGE/UMTS/LTE For guaranteeing continuity of existing GSM services, ZXUN vgw supports services and subscribers of GSM, EDGE, UMTS, and LTE. It also facilitates an easy migration of the subscribers from GSM/EDGE/UMTS to LTE, as no changes happen to network topology or network element configurations during the upgrades. ZXUN vgw supports access of GERAN/UTRAN/E-UTRAN network simultaneously. One unified core network could reduce investment greatly with resource sharing: Sharing of signaling process, call process, switch resources etc, saves investment and ensures smooth evolution. Soft capacity: During the evolution from 2G/3G to LTE, either 2G/3G or LTE user number may increase suddenly. ZTE equipments automatically adjust the system resources to meet capacity requirements of 2G/3G and LTE. Resource sharing could be based on any 2G/3G/LTE service ratio. Thus, the evolution becomes very smooth. Unified operation and management system could also decrease investment. Facility such as transmission and equipment room could be shared. 2.5 Open interface and Flexible Networking Capabilities ZXUN vgw products provide open and standard interfaces and allow smooth upgrades and expansion. 10 ZTE Confidential & Proprietary

13 Support of High speed Ethernet transport allows its integration into any of the existing networks. Safe integration without impact is also ensured by supporting the legacy interfaces and signaling protocols towards the existing network elements. For implementing authentication and charging (for some enterprise users) function, ZXUN vgw connects with Radius server. ZXUN vgw supports Gy interface (based on diameter protocol) to connect with OCS for online charging and supports Gx interface (also based on Diameter protocol) to connect with PCRF for Policy and Changing control. 2.6 High Reliability ZXUN vgw Like other new technologies in their early adoption phase, NFV faces the concerns of reliability by some of service providers. The uses of COTS and adding a virtualization layer have been particularly considered a reliability risk. To address these concerns, ZTE applies a number of innovations to the design of ZXUN vgw. ZTE addresses the reliability concerns by two approaches: Approach 1 - Distributed data backup. UE data block is hashed into different VMs and each UE data block is backed up by a different VM. Data synchronization between VMs for UE data block is triggered by the UE data changes. Approach 2 - Multi-level redundancy. As illustrated below for virtualized network function (VNF) deployment, we apply multi-level redundancy to the design. First we apply active, standby or load sharing to the VNFs being deployment. Second, we apply VM migration and rebirth to the virtual machines that a VNF runs on. Third, we provide redundant hardware resources in the pool. The multi-level redundancy can significantly reduce the MTTR (mean time to repair). ZTE Confidential & Proprietary 11

14 2.7 Fast Deployment ZXUN vgw configures parameters like PDP number, traffic threshold and traffic model etc. by man-machine interface, then the system will calculate out required VM quantity, required memory, CPU cores and NICs of every VM and deploy those VMs on the cloud platform automatically. At the same time, the system will also complete service configuration, so vgw is ready for packet service. Comparing to hardware installation, wiring and power on operation of the traditional router, vgw deployment is much faster and easier. 2.8 Elastic Scalability ZXUN vgw allocates resource to provide packet service dynamically according to the traffic status. When the system is running, vgw will decide whether expand VM quantity or VM capacity by considering various information including current PDP number, current VM CPU occupancy, current traffic volume and historical traffic curve, this procedure is initiated by automatic system recognition and without any manual interference. 2.9 Abundant Service Functions ZXUN vgw supports all GPRS/UMTS/LTE data services and the interaction with IMS domain. Its design meets the future communication development trend, and also structure requirements of mobile telecommunications systems such as GSM/UMTS and LTE as well as the requirements of various new services Smooth Expansion Capabilities Smooth evolution with Investment Protection: Adopting the access agnostic gateway, its hardware could be reserved and reused when evolving from GSM/UMTS to LTE to protect investment on gateways. 12 ZTE Confidential & Proprietary

15 ZXUN vgw adopts hierarchical and modular structure and could be flexibly expanded and applied. It also offers flexible configuration for operators Convenient Operation Maintenance C/S structure is adopted to ensure high networking capability and expandability of ZXUN vgw. Adopting Windows operating system, the client provides user-friendly interfaces and flexible, convenient and reliable operations. Multiple remote and local system access ways are supported to allow implementation of O&M either locally or remotely for managing the whole system or some specific entities. O&M is featured with high security and multi-level authorization protection. With such functions as charging management, performance measurement, traffic statistics, security management, service observation, user (equipment) tracing, signaling tracing, data configuration, version upgrading, alarming, loading, data backup and transmission, the system provides multiple accurate, reliable, practical and convenient O&M approaches. These functions could be added according to the actual network operation and the operator s requirements. The O&M system provides user-friendly interfaces, comprehensive functionality and flexible networking capability to implement centralized management over all kinds of network entities of GSM/UMTS/LTE. ZTE Confidential & Proprietary 13

16 3 Functionality This chapter describes the abundant services and functions provided by the vgw for GSM/UMTS/LTE subscribers. 3.1 Session Management This topic describes the session management functions of vgw. The vgw could be deployed as a GGSN for GSM/UMTS network, which realizes PDP context related management functions such as PDP activation, deactivation, and modification. The vgw could also be deployed as a SAE-GW (SGW and / or PGW) for LTE network, which realizes EPS bearer related management functions such as session creation, dedicated bearer creation, and bearer modification. The following PDP context management procedures are supported for GPRS/ UMTS: PDP Context Activation Update PDP Context Delete PDP Context PDP Deactivation of Inactive Subscriber DL bearer binding Secondary PDP Context Activation Network Initiated PDP Context Activation The following EPS bearer management procedures are supported for EPS: PDN Connection Activation PDN Connection Modification PDN Connection Deactivation 14 ZTE Confidential & Proprietary

17 Dedicated Bearer Activation Bearer Modification Bearer Deactivation 3.2 GTP Management This topic describes the GPRS Tunneling Protocol (GTP) function of ZXUN vgw. As GGSN, GTP tunnel is created for each PDP context between GGSN and SGSN /RNC for data forwarding. As SAE-GW, GTP tunnel is created for each EPS bearer between PGW and SGW or SGW and enodeb for data forwarding. ZXUN vgw supports the GTP path management as defined in 3GPP. Tunnel management message is used to manage the tunnel between GSNs, RNC and GSN, SGSN, MME, SGW and PGW. Uplink and downlink signal/data are transmitted through the tunnel. Location Management messages are defined to support the case when Network-Requested PDP Context Activation procedures are used and a GGSN does not have a SS7 MAP interface, i.e. a Gc interface. GTP is then used to transfer control plane messages between the vgw and a GTP-MAP protocol-converting GSN in the GPRS backbone network. ZXUN vgw supports different GTP version V0, V1 and V2 as described in 3GPP protocols. Thus, ZXUN vgw supports simultaneous access of GSM/EDGE, UMTS and LTE users and simultaneously performs session management of all three kinds of users. The vgw deployed as GGSN or SAE-GW supports moving between Gn/Gp SGSN and MME for user. ZTE Confidential & Proprietary 15

18 3.3 Direct Tunnel (DT) This topic describes the direct tunnel function of the vgw. For 3G network, the GTP-U tunnel is created between GGSN and RNC; For EPS network, the GTP-U tunnel is created between PGW and RNC. ZXUN vgw deployed as GGSN or PGW support R7 Direct Tunnel function; traffic in User Plane goes directly from UTRAN to vgw, no more goes through Gn/Gp SGSN as in previous PS architecture. Figure 3-1 Gn/Gp SGSN DT Architecture RNC Iu SGSN Gn Two tunnels PGW/ GGSN Legend: GTP User plane GTP signalling RANAP signalling Gi Interface Gi Direct tunnel 3.4 IP Address Management This topic describes the IP address allocation methods available for mobile users. When the GGSN/ PGW receives PDP context activation request for session creation request, an IP address is allocated to the UE making the request. The following IP address allocation method can be supported: IP address allocation via local Pool IP address allocation via DHCP server IP address allocation via RADIUS server 16 ZTE Confidential & Proprietary

19 3.5 Routing This topic describes the IP packet routing function of the vgw. The GGSN/ PGW working as gateway to Packet Data Network (PDN) provides IP packet routing function between devices in PDN and GSM/UMTS/LTE equipment. The SGW function provides IP packet routing function from PGW to enodeb. In addition to the basic static routing, the following routing functions are also supported by ZXUN vgw. Static Routing OSPF Policy Based Routing The vgw also supports the following for routing security and reliability. Multiple Routes Redundancy VRF BFD 3.6 APN This topic describes the access point name (APN) function of the vgw. The APN is a network identifier defined by the GSM/UMTS/EPS to indicate which PDN to access. Packet Data Network (PDN) is the network accessible from mobile network as defined in 3GPP. For example internet and Intranet are two different PDNs for mobile subscribers to access from GSM/UMTS/ LTE. Each packet data network (PDN) has different attributes to be used for subscribers to access and operator to control, such as the IP addresses for allocation, the allocation method, authentication or not, traffic planning, control functions on the subscribers, etc. ZTE Confidential & Proprietary 17

20 For example, the intranet may use different IP pool than internet and additional authentication on subscribers using external radius server. For each APN used by the operator, the GGSN provides related attributes configuration for this APN for the packet data network (PDN) to be accessed. In addition to the basic APN related function, the vgw can also provide Single APN and APN Alias function. When attaching, GGSN/ PGW decides user s service network according to the APN in user s request, which request many APN. But when GGSN/ PGW use the single APN function, GGSN/ PGW does not use APN to decide service network. User uses username and password when attaching. GGSN/ PGW gets service selector from username,; example: wap.in.tom@wap will tell GGSN/ PGW that user wants to access wap service and net.in.tom@net indicates that user wants to access internet service. This single APN function makes users avoid the trouble that they need modify APN configuration when visiting different kinds of service. APN alias supports mapping different APNs received from users to one APN configured in GGSN/ PGW, where several APNs could be equal to one APN configuration. GGSN/ PGW configure an APN, then creates index of APNs mapping to the APN configuration. When GGSN/ PGW receives a default bearer creation request, GGSN/ PGW checks the APN. If it finds the APN is alias APN, GGSN/ PGW searches in the APN index and deploys the APN configuration. 3.7 VPN This topic describes the virtual private network (VPN) service of intranet for enterprise users provided by the GGSN/ PGW. The vgw supports tunneling technologies such as VLAN, Generic Routing Encapsulation (GRE) and Layer 2 Tunneling Protocol (L2TP). VLAN VPN 18 ZTE Confidential & Proprietary

21 For Fast Ethernet and Gigabit Ethernet interfaces, the software of ZXUN vgw supports IEEE 802.1Q standard for channelizing an Ethernet interface into multiple logical interfaces, separating different traffic in many virtual LANs (VLANs) to be transported over the same physical circuit, but preventing them from being in the same routing or broadcast domain. GRE VPN The GRE is the layer 3 Tunneling technique. In this, private IP packets are encapsulated in public IP packet with GRE header. The GRE feature enables the usage of tunnels between ZXUN vgw and external hosts or routers (Gi/ SGi interface). This tunneled transport provides traffic separation between the different Gi/ SGi networks. The GRE feature can also be used on any other interfaces as well such as S5/S8, Gp interfaces. ZXUN vgw supports GRE function as specified in RFC1701 and RFC1702. L2TP VPN L2TP is the layer 2 Tunnel protocol. It is mainly used to extend PPP link, extending the user dialup to enterprise gateway from NAS (Net Access Server) to realize the VPDN (Virtual Private Dial Network). L2TP creates a L2TP tunnel between the LAC (L2TP Access Concentrator) and LNS (L2TP Network Server), by which LAC transports the user s PPP Frame to LNS via public Internet. ZXUN vgw supports L2TP feature as specified in RFC1661 and RFC2661. The VPN service provides the mobile subscribers a more flexible, reliable and security methods to access the intranet. The operator is allowed to do independent dimensioning including IP address planning and traffic planning for each VPN because vgw supports logical or physical traffic separation with VLAN or dedicated physical interface and routing separation with dedicated VRF VPN for each VPN. ZTE Confidential & Proprietary 19

22 3.8 Radius Client This topic describes the Radius client function of the vgw. When vgw deployed as GGSN, GSM/UMTS subscribers are authenticated for PDN service by Radius server via radius client in vgw. When vgw deployed as PGW, LTE subscribers are authenticated for PDN service by Radius server via radius client in vgw. The vgw supports Radius charging function, which reports relative charging information to external Radius server via radius client in vgw. The vgw also supports radius server initialized PDP or EPS bearer deactivation due to out of balance or other reason. 3.9 Security This topic describes the security function of the vgw. The security function is used to protect the GGSN/ SAE-GW from being attacked by other device, to protect the service from being used by unauthorized users, to protect the information from being intercepted by hostile attackers and to provide lawful interception. ZXUN vgw provides a systematic security policy from lower layer as IP layer to service layer to protect the network and service. Traffic separation The traffic of mobile network encompasses OM/billing system traffic, internet traffic, intranet traffic and traffic between network elements within the network. These different types of traffic are facing different level of security attacks, for example internet traffic is always be facing the most dangerous attacks while traffic between network elements within the network is considered much secure. Separation of traffic with different security levels limits the attack within the minimum areas and protects most equipment from facing the most dangerous attacks. ZXUN vgw provides logical or physical traffic separation for OM, billing, Gi /SGi, Gn, Gx, Gy, etc. ZXUN vgw also provides dedicated routing table (VRF) for the separated traffic as shown in the following figure. Figure 3-2 Separated Traffic Architecture by VRF 20 ZTE Confidential & Proprietary

23 OM Domain Internet Domain (SGi/ Gi) ZXUN xgw Billing Domain Intranet Domain (SGi/ Gi) Gn Domain Traffic authentication With these functions, the traffic in each domain is limited to device authorized only. In Intranet IP access mode, the GGSN/ PGW authenticate and authorize mobile stations (MSs) by interworking with the authentication, authorization, and accounting (AAA) server. For important routing protocols, such as Open Shortest Path First (OSPF), the vgw provides multiple authenticating methods. ACLs Access Control Lists for IP layer offer an important tool for controlling traffic in the IP network. These lists are used to filter the in or out IP packet flow of each vgw s interfaces based on source IP, source port number, destination IP, destination port number and protocol type. ACLs prevent the attack to network elements from unknown device or UE. Anti-spoofing The anti-spoofing function provides the network with the capability to check whether the packet uses the same IP-Address that was assigned to the UE. For each uplink packet, the GGSN/ PGW checks the source IP address against the IP address allocated to the UE. If the source IP address is different from the IP allocated to UE, ZTE Confidential & Proprietary 21

24 it is considered as a spoofing packet and GGSN/ PGW drops it or even deactivates the PDP context or EPS bearer. In addition, the system also logs this information and reports to analysis system for further processing. With this function, the network is protected from IP spoofing from mobile terminal. Bearer Binding Verification GGSN or PDN GW checks the uplink package of each PDP context or EPS bearer against the bearer s uplink filters. This is to verify that the UE applies the UL packet filters correctly and does not misbehave, e.g., by sending packets on a "default bearer" even though the packets do not match the UE's UL packet filters associated with that "default bearer". With this function, it is ensured that UE applies the UL packet filters correctly and does not misbehave. MS-to-MS Traffic Control of Same APN ZXUN vgw can configure following control policies per APN, such as: Allow MS-to-MS traffic of same APN. Force to forward MS-to-MS traffic of same APN to Gi interface. Deny MS-to-MS traffic of same APN. It benefits operators to control MS-to-MS traffic flexibly, according to specific service characteristic and APN requirement to improve network security level QoS This topic describes the Quality of Service (QoS) guarantee function of GGSN or SAE-GW. GGSN or SAE-GW provides the needed quality of service control for different type of service. 22 ZTE Confidential & Proprietary

25 3GPP defines that an End-to-End Service has a certain Quality of Service (QoS) that is provided for the user of a network service. To realize a certain network QoS a Bearer Service with clearly defined characteristics and functionality is to be set up from the source to the destination of a service. A bearer service includes all aspects to enable the provision of a contracted QoS. These aspects are among others the control signaling, user plane transport and QoS management functionality. A UMTS/ EPS bearer service layered architecture is depicted in the following figure, each bearer service on a specific layer offers its individual services using services provided by the layers below (such as IP layer in transportation network). Figure 3-3 E2E QoS Architecture UMTS TE MT RAN CN EDGE NODE End-to-End Service CN Gateway TE TE/MT Local Bearer Service UMTS Bearer Service External Bearer Service Radio Access Bearer Service CN Bearer Service Radio Bearer Service RAN Access Bearer Service Backbone Bearer Service Physical Radio Bearer Service Physical Bearer Service For UMTS/ EPS bearer service, the QoS is supported during the context/bearer activation with the negotiated QoS parameter requested for the service. These UMTS/ EPS QoS parameters are mapped to the differentiated services code point in IP layer for providing IP backbone service when the traffic passing through the IP transportation network. ZTE Confidential & Proprietary 23

26 The vgw supports DiffServ edge function, which is compliant to the IETF specifications for Differentiated Services (RFC 2475 [6]). The IETF Differentiated Services architecture is used to provide QoS for the external bearer service. Mapping of QoS parameters to the DiffServ Code Point (DSCP) in the downlink GTP IP header contributes to secure correct QoS handling through the backbone network. Mapping of QoS parameters to the "DiffServ Code Point" in the uplink user packet to secure correct QoS towards and through the external network. Mapping of 3GPP QoS parameters to DSCP (DiffServ Code Point) values and the mapping is configurable. The vgw also provides DSCP remarking function for packet from un-trusted network based on local policy. The vgw supports bit rate limitation function. The vgw provides service based bit rate limitation for each subscriber within one PDP context or EPS bearer with integrated service awareness function. The vgw supports policy based QoS control. The vgw supports PCEF function to enforce QoS policies from PCRF via Gx interface. Local policy based QoS control could also be supported by vgw. With policy based QoS control, the vgw provides differentiated QoS control for different subscribers, different service type, different network type (2G/3G/ LTE) and even different place or time Service Awareness and DPI This topic describes the Service Awareness or DPI function of GGSN or SAE-GW. Service identification function of GGSN/ PGW is used to classify each type of service accessed by each subscriber for further processing, such as access control, routing/ redirection control, QoS control and charging control. Basic Service Detection By L3/L4, L7 information, ZXUN vgw supports to differentiate following services, such as, HTTP1.0/1.1,WAP 1.X/2.0, HTTPS, POP3, SMTP, IMAP4, FTP, MMS, RTSP, RTP/RTCP, DNS, etc. DNS-based service identification flow Figure 3-4 DNS-based Service Identification Flow 24 ZTE Confidential & Proprietary

27 MS GGSN DNS Server Internet DNS Query DNS Response Data ZXUN vgw identifies DNS messages between MS and DNS Server, and gets mapping relationship between Domain Name and server IP address by inspecting the DNS response message. Then it checks if destination IP address of a message is in the mapping table or not when the message passes by. If YES, it is known that the message is going to the server with the configured Domain Name. Enhanced DPI Enhanced DPI Function also known as HPI (Heuristic Packet Inspection).This function means to use more complicated rule to identify the packet protocol through fuzzy identification, event identification, etc. Enhanced DPI adopts complete feature base and provides user with the latest protocol identification capability. With enhanced DPI, operators are able to analyze the protocol that simple DPI cannot identify, improving service identification ratio, so as to realize more detailed service control Policy Control This topic describes the policy control function of the vgw. Working as GGSN/ PGW, the vgw supports PCEF function providing policy control for 2G/3G/LTE subscribers. The vgw supports static policy control configured in local GGSN or PGW, and dynamic policy control from PCRF via Gx interface. The PCEF encompasses service data flow detection, policy enforcement and flow based charging functionalities. ZTE Confidential & Proprietary 25

28 PCEF is located at the Gateway. It provides service data flow detection, user plane traffic handling, triggering control plane session management (where the IP-CAN permits), QoS handling, and service data flow measurement as well as online and offline charging interactions. The PCEF enforces the Policy Control as indicated by the PCRF in two different ways: Gate enforcement. The PCEF allows a service data flow, which is subject to policy control, to pass through the PCEF if and only if the corresponding gate is open. QoS enforcement. QoS class identifier correspondence with IP-CAN specific QoS attributes. The PCEF converts a QoS class identifier value to IP-CAN specific QoS attribute values and determines the QoS class identifier value from a set of IP-CAN specific QoS attribute values. PCC rule QoS enforcement. The PCEF enforces the authorized QoS of a service data flow according to the active PCC rule (e.g. to enforce uplink DSCP marking). IP-CAN bearer QoS enforcement. The PCEF controls the QoS that is provided to a combined set of service data flows. The policy enforcement function ensures that the resources which can be used by an authorized set of service data flows are within the "authorized resources" specified via the Gx interface by "authorized QoS". The authorized QoS provides an upper bound on the resources that can be reserved (GBR) or allocated (MBR) for the IP-CAN bearer. The authorized QoS information is mapped by the PCEF to IP-CAN specific QoS attributes. Charging control The PCEF enforces the charging control as follows: Get Charging type from PCRF, such as Online, Offline; Get Charging key from PCRF, such as SI and RG ; Supporting Enhanced Gx Interface 26 ZTE Confidential & Proprietary

29 Enhanced Gx interface is located between PCEF and PCRF, and PCRF gets user s subscription data from SPR. With enhanced Gx interface, vgw support following features: Report charging characteristic to PCRF in CCR message: PCEF reports current users information to PCRF through enhanced Gx interface during bearer context activation or bearer context update. In order to meet the requirement of PCC deployment, ZTE extends Gx interface parameters including charging characteristic in CCR request to support more various policy decisions. Support HTTP redirection and user class in CCA authorized by PCRF: With enhanced Gx interface, PCRF can authorize HTTP redirection control or user class in CCA, and vgw will execute HTTP redirection or deploy policies according to authorized user class. Fair Usage Policy ZXUN vgw reports service usage and user usage to PCRF according to the usage threshold form PCRF, and PCRF accumulates user and service usage. Then PCRF provides specific policy according to actual user and service usage. PCEF executes specific policy from PCRF. Detailed policy includes access control, QoS control or redirection, etc. PCRF is also able to set different accumulated service usage for user or one service with various situations including subscriber type, roaming, radio access type (GREAN/UTRAN/E-UTRAN), location (roaming or not), time (busy or idle time), etc. W&B List Control W&B List (White and Black List) is configured by combining subscriber information and service information. When subscriber accesses specific service, GGSN may deny or allow service by checking W&B list. Redirection control ZXUN vgw supports traffic redirection function for Web (http), WAP 1.x an WAP 2.0. ZTE Confidential & Proprietary 27

30 3.13 Charging This topic describes the charging function of the vgw. Working as GGSN/ SAE-GW, different charging methods could be provided to 2G/3G/LTE subscribers. Radius Charging When the subscriber is activated, GGSN/ PGW sends subscriber data flow into Radius server through standard Radius signaling for 2G/ 3G/ LTE subscriber charging purpose. In the information, the accessory charging attributes include MSISDN, IMSI, IMSI-MCC-MNC and Selection Mode, Charging ID, Charging Characteristics and GGSN/ PGW IP Address. Offline Charging When implementing a service, the GGSN generates G-CDRs. G-CDRs are used in recording user data flow information. Some CDRs generated according to different charging policies need to be merged in the CG. For SAE-GW, when implementing a service, the PGW generates PGW-CDR and SGW generates SGW-CDR. CDRs are used in recording user data flow information. Some CDRs generated according to different charging policies need to be merged in the CG. CDRs could be encoded according to 3GPP TS or according to the requirement of operator. Charging based on Time and volume is supported. ZXUN vgw automatically caches subscriber CDRS that cannot be sent because of link failure, avoiding CDR loss due to charging link interruption to guarantee the correctness of charging information. ZXUN vgw supports GTP protocol based Ga interface to interconnect with standard CG for transmitting standard PS/ EPS CDR. Online Charging 28 ZTE Confidential & Proprietary

31 OCS (Online Charging System) is the trend of charging for 3GPP network and service network. It realizes the integrated charging process for a prepaid user who enjoys all kinds of telecommunication services such as CS, PS, IMS, and applications. Diameter CC protocol is the interface standard of OCS, and it is based on IP network. ZXUN vgw supports Gy interface that is based on Diameter CC protocol as specified in 3GPP TS , 3GPP TS , RFC 3588, RFC 4006, and 3GPP TS Interworking with OCS, ZXUN vgw performs service authorization, quota request and update. Service and Content Charging ZXUN vgw supports the service and content charging function as described in 3GPP and ZXUN vgw could filter the user data from layer 3, layer 4, and layer 7 (namely, by source IP segment, destination IP segment, source PORT range, destination PORT range, protocol type, URL), and set different charge rate for different filter rules, realizing the flexible charging method for the operator. Service based Event Charging ZXUN vgw supports event charging for following services, such as HTTP/WAP2.0, WAP1.X, Video streaming(only for RTSP), POP3, SMTP, IMAP4, FTP download, etc IPv6 This topic describes the IPv6 function of the vgw. The GGSN supports 2G/3G subscribers creating IPv6 type PDP context to IPv6 PDN, and PGW supports LTE subscribers creating IPv6 type or IPv4v6 type EPS bearer to IPv6 PDN. The IP address allocated for the default bearer is also used for the dedicated bearers within the same PDN connection. IP address allocation for PDN connections, which are activated by the UE requested PDN connectivity procedure, is handled with the same set of mechanisms as those used within the Attach procedure. ZTE Confidential & Proprietary 29

32 ZXUN vgw supports IPv4, IPv6 and IPv4v6 PDN types. An EPS Bearer of PDN type IPv4v6 may be associated with one IPv6 prefix only or with both one IPv4 address and one IPv6 prefix. PDN type IPv4 is associated with an IPv4 address. PDN type IPv6 is associated with an IPv6 prefix. PDN types IPv4 and IPv6 are utilized for the UE and/or the PDN GW to support either IPv4 addressing or IPv6 prefix; or operator selects to use single IP version only, or the user subscription is limited to IPv4 only or IPv6 only for the specific APN. In addition, PDN type IPv4 and IPv6 are utilized for interworking with nodes of earlier releases. To support the usage of IPv6 address, in addition to the basic IPv6 packet forwarding between SGSN and GGSN/SAE-GW within GTP-U tunnel, the GGSN/ PGW supports IPv6/IPv4 stack or IPv6 in IPv4 tunnel at Gi/ SGi interface as shown in following figure. Figure 3-5 E2E IPv6 Architecture Application IPv6 IP IP Relay Relay PDCP PDCP GTP GTP GTP GTP RLC RLC UDP/IP UDP/IP UDP/IP UDP/IP MAC MAC L2 L2 L2 L2 L1 MS L1 L1 L1 L1 L1 RNS/eNodeB Iu/S1 SGSN/SGW Gn/S5 GGSN/PGW Gi/SGi 3.15 SGW and PGW Combination This topic describes the combo function of SGW and PGW combination function of the vgw. The SGW and PGW combination means the vgw supports SGW and PGW at the same time in one physical node for LTE subscribers. Because SGW and PGW are implemented in one physical node, some hardware could be shared to reduce the CAPEX. For example, the interface to charging system and OM system could be shared. 30 ZTE Confidential & Proprietary

33 When SGW and PGW implemented in one node, there is only two hops in EPS user plane: one is enodeb and the other is ZXUN vgw. So transport delay for user package is significantly reduced Capacity Sharing between 2G/3G/LTE This topic describes the capacity sharing between 2G/3G/LTE of the vgw. This function means the vgw support 2G/3G/LTE subscribers at the same time, and the system capacity of 2G, 3G and LTE is shared with each other. ZTE vgw supports 2G/3G/LTE access. With ZTE vgw deployment, one physical node provides access to 2G, 3G, and LTE users. To further save the operator s CAPEX, the hardware resource in vgw could be shared between 2G/3G/LTE users as a pool. For example the number of bearer contexts/pdp contexts supported by vgw could be shared. Because of multi-mode UE mobility between GERAN/UTRAN/E-UTRAN, the number of users in each network is changing all the time but the whole number of users in GERAN, UTRAN and EUTRAN could be fixed. Resource sharing in vgw satisfies the whole capacity of GERAN, UTRAN and E-UTRAN with the minimum CAPEX Network Data Collection and Reporting When DPI report function of UBAS is enabled, vgw extracts and reports user s detailed packet information to UBAS server. UBAS provides the report on the volume, connection amount and duration of different service type. UBAS also provides report of visited URL. Through this feature, Operator has a comprehensive understanding on the service type and development situation of the network, knows more about user s data service usage and preference, so as to realize the bandwidth management and optimized operation of mobile internet. Combined with CHR(reference chapter Calling History Report ), UBAS achieves service analysis of different dimension, such as service type, protocol type, route area, ZTE Confidential & Proprietary 31

34 APN, NE, etc. Operator is able to know the network volume distribution and service development Other Service and Function ZXUN vgw also supports management and maintenance related function and NTP client for time synchronization. 4 System Architecture ZXUN vgw complies to ETSI NFV standards, one NFV network element has 3 layers: hardware layer, virtualization layer(cloud platform and VM technology) and service software layer, following 3 paragraphs describe those layers respectively, and in the end ZXUN vgw VM deployment architecture is also described. 4.1 Hardware ZXUN xgw may deployed on ZTE hardware platform or third party hardware like HP and DELL etc. 1. HP BladeSystem C7000 HP BladeSystem C7000 is an enterprise/datacenter server. 32 ZTE Confidential & Proprietary

35 The 10U high shelf can support up to 8 full-height blades and 16 half-height blades. A half-height blade has dual Intel Xeon processors as one processing unit with 8~12 cores and up to 512GBytes memory. A full-height blade has quad Intel Xeon processors as one processing unit with 8~12 cores and up to 1TBytes memory. A processing unit offers a 100Mbytes management network port and two GE interfaces, which can be extended to six 10GE interfaces by using PCIE sub cards. It supports configuring SATA/SAS hard disk and connecting external drive. A shelf has backplane to provide external connection ports going through the rear card. The rear card supports three dual HP Virtual Connect (VC) modules or HP blade switches customized by Cisco H3C. Each VC module supports internal 16 10GE interfaces and external 8 10GE interfaces. It has strong support for virtualization management. 2. ZTE ATCA platform ZTE Confidential & Proprietary 33

36 ATCA platform integrates dual Intel Xeon processors as one processing unit with up to 8*8GBytes memory. Considering the heat dissipation of the ATCA blade, CPU is running at 1.9GHz frequency only and cannot work at full frequency (while the CPU of other types of blade works at 3GHz frequency). ATCA has backplane to provide each blade with two GE internal interfaces for intra-shelf connection and two GE external Ethernet interfaces for inter-shelf connection. Meanwhile the optional configuration of Fabric sub card allows two 10GE interfaces. Each blade node can mount two hard disks. ATCA uses 14U shelf, and each shelf can mount 12 servers. ZTE s ATCA shelf adopts high-reliability design and has low requirements on equipment room. Compared with IT servers, it has lower computing density, storage density and network density. 3. ZTE E9000 enterprise server platform Compared with the ATCA blades, E9000 enterprise servers have higher power consumption and computing density. The 10U high shelf can support up to 8 full-height blades and 16 half-height blades. A half-height blade has dual Intel Xeon processors as one processing unit with up to 16*8GBytes memory, which can work at full capacity. It supports two removable hard disk and two GE interfaces, which can be extended to four 10GE interfaces or two 10GE interfaces and two FC interfaces by using PCIE slots. 34 ZTE Confidential & Proprietary

37 A full-height blade has quad Intel Xeon processors as one processing unit. The backplane offers a rear switch with three dual switching modules. Each switching module has 16 10GE interfaces for intra-shelf connection and 8 10GE interfaces for inter-shelf connection. 4. Dell s PowerEdge C8000 servers Dell PowerEdge C8000 series has high-density 4U shelf to hold 10 to 12 blades. Each blade integrates dual Intel Xeon processors as one processing unit, which is installed with one OS. The processing unit offers a 100Mbytes management network port and two GE interfaces, which can be extended to two 10GE interfaces. Eight cores of each processors contribute to 16 cores with up to 16*8GBytes memory and large-capacity hard disk. A rack can hold 10 4U shelves to bring ultra-dense. 5. Cisco UCS 5100 series blade servers ZTE Confidential & Proprietary 35

38 Cisco UCS 5100 series as 6U high shelf, which can accommodate up to eight half-width, or four full-width blade servers with the same shelf. A half-width blade has dual Intel Xeon processors as one processing unit with up to 16*8GBytes memory. The processing unit supports two removable hard disk and two 10GE interfaces. A full-width blade has quad Intel Xeon processors as one processing unit with up to 32*8GBytes memory. The processing unit offers two removable hard disk and four 10GE interfaces. Since there is no intra-shelf connection, the physical connection of a shelf leads out from the rear card to an external switch and optional uplink modules for interconnection. The datacenter is a 1U high Nexus 1000 series switch with 40 10GE interfaces. 4.2 CMS and Hypervisor Cloud platform operation system (CMS) is running on universal server hardware platform, it provides elastic and scalable group management, and allocates quantified resource to different applications. CMS screens the hardware and lower layer of operation platform, provides identical running environment for applications to implement deployment in large scale. Applications are deployed on CMS platform in distributed way. ZXUN vgw supports CMSs including OpenStack, VMware vsphere and ZTE OpenCos(Open Cloud Operation System). Hypervisor is the middle ware between physical server and OS, it allows multiple OSs and applications to share hardware. Hypervisor not only coordinates the access on the hardware, it also provides protection for every VM. When server starts Hypervisor, Hypervisor will load OSs of all VM clients and allocate memory, CPU, network and hard disk to every VM. Hypervisor may be viewed as the general term of VM implementation, every VM technology is a type of Hypervisor implementation. ZXUN vgw supports Hypervisors including KVM, VMware and XEN. 36 ZTE Confidential & Proprietary

39 4.3 Software Architecture The ZXUN vgw is an integrated distributed processing network gateway. Software structure of it follows a modular and layered design principle. Invoking between layers is unidirectional in the primitive mode, and that between modules of the same layer is in the message interface mode, requiring independent modules and universal inter-module interface. The ZXUN vgw software structure follows the same principle and is composed of a series of functional subsystems. These subsystems are independent of each other, and communicate with each other with the message mechanism. Each subsystem is further divided into multiple functional modules. The ZXUN vgw software system is composed of the CGEL (Carrier Grade Embedded Linux) subsystem, TULIP (Telecom UniversaL Integrated Platform) subsystem, PM (Product Management) subsystem, ROSng (next generation Route OS) subsystem, database subsystem, OAM subsystem, service processing subsystem and package forwarding subsystem. Following figure shows the software structure of ZXUN vgw. Figure 4-1 Layered Structure of vgw Software System OAM Subsystem Service Subsystem PM Subsystem Rosng Subsystem DB Subsystem TULIP Subsystem Packet Forward Subsystem CGEL Subsystem Hypervisor ZTE Confidential & Proprietary 37

40 TULIP Subsystem: TULIP subsystem shields the difference between different type of OS and processors to provide one real time distributed application platform for upper level service. PM (Product Management) Subsystem: This subsystem is in charge of providing functions such as software release management, equipment management, package forwarding plane management, control and forwarding communication. Rosng Subsystem: This subsystem provides routing protocol function such as different kinds of routing protocols including OSPF, BGP, multicast, etc and different kinds of VPN. OAM Subsystem: This subsystem implements operation, maintenance, performance statistics, data configuration and fault management functions for the vgw. DB Subsystem: On the basis of the OS, it is independent of the application database system. It uses the object-oriented relation data mode to manage the data, including defining, describing, operating and maintaining the data table. It flexibly provides and performs the system data configuration, maintenance and other functions. It also stores and manages the subscriber data and other subscriber s information, for providing the mobile subscriber efficient and reliable data service. Service Subsystem: This subsystem provides service functions for subscribers, such as activating, updating, and deactivating service functions and encapsulating and de-capsulation data. 4.4 ZXUN vgw VM Deployment After ZXUN xgw has been virtualized, service application is deployed on VM, the lower layer hardware is isolated. ZXUN vgw VM deployment architecture is shown in the Figure 4-2, every VM has been deployed a processing module/component. If the component supports 1+1 active/standby backup, then 2 VMs will have same components to backup each other. GSU module/component supports both 1+1 active/standby backup and N+1 backup. Figure 4-2 SAE-GW/GGSN VNF Architecture and Components 38 ZTE Confidential & Proprietary

41 BOSS Orchestrator EMS VNFM AD CMS SAE-GW/GGSN UOMM OMU GSU UOMP LBU GSU UOMP STU GSU OMM connection PFU PFU PFU PFU GSU VMs CMS Management Connection Internl Control Plane Switch Network Internal Media Plane Switch Network enodeb MME/SGSN OCS/PCRF Internet Table 4-1 Module/component supported by NFV SAE-GW/GGSN Component Correspo nding VM Function Redundancy mode ZTE Confidential & Proprietary 39

42 Implementing the FCAPS function. Collecting the performance detection results of PPs (Including LBU, STU, GSU and PFU) and determining whether to trigger and control the elastic scale OMU procedure. (operation and management Unit) 2 VM Rebooting and customizing a VM upon reception of VNFM commands. Monitoring the VM status, such as CPU utilization, VM memory utilization, virtual disk utilization and network QoS, and reporting the monitoring information to VNFM and EMS. 1+1 active/standby Implementing the SAE-GW/GGSN operation and management. LBU (Load Balancing Unit) 2 VM Service access Load balancing. Distribute user access to each GSU for load sharing. 1+1 hot standby STU (Signaling Transfer Unit) 2 VM Signaling transferring. Implementing signaling link (such as diameter link and etc) setup, management and signaling packet transferring. Load balancing 1+1 redundancy GSU (General Service Unit) N+1 VM Handling service access, offline/online charging, and PCC policy control. N+1 hot standby 1+1 hot standby PFU (Packet Forwarding Unit) N+1 VM Handling external IP Interface, service awareness, and packet forwarding (including signaling packet and User-Plane packet). N+1 redundancy 40 ZTE Confidential & Proprietary

43 5 Technical Specifications 5.1 Interface Indices The following table lists the standards and supported cables for ZXUN vgw interfaces. Table 5-1 ZXUN vgw Interface Standards and Cables Interface Type Physical Standard S1-U/ S11/ /S5/S8/Gn/Gp SGi/Gi Gx/Gy GE/10GE Ga Network management GE 5.2 Capacity Indices Table 5-2 ZXUN vgw Capacity Indices Technical Parameter Features Specific Indices Capacity Indices Maximum of activated EPS bearer/pdp context per GSU Maximum throughput per PFU 100K Interface Indices GE interface PFU Num *2 10GE interface PFU Num *2 ZTE Confidential & Proprietary 41

44 6 Operation and Maintenance The Network Management System (NMS) comprises the Operation & Maintenance Center (OMC) and charging management parts. It provides perfect authentication mechanism to avoid illegal access. The OMC comprises O&M server and O&M terminal. The charging management part consists of CG processing unit, charging terminal and charging OMM server. The structure of NMS is as shown in the following figure. The OMC provides advanced management capability. It provides centralized control of different types of NEs in GPRS/WCDMA/LTE with powerful networking capability. It also provides the cascading control and the reverse operation. It realizes remote access by accessing WAN via routers. Figure 6-1 O&M System Structure 42 ZTE Confidential & Proprietary

45 The charging operation server provides centralized configuration and processing of packet domain and powerful charging mechanism control, to satisfy the charging content requirements in charging content time, flow, quality and service. A dual-system mechanism is adopted to guarantee that charging is running without fault. The charging system provides diversified interfaces and FTP/FTAM file transmission mode to output bill contents. The NM system is divided into foreground module, server module and client module according to software structure. The whole software frame complies with TMN (telecommunication network management) structure. Functionally, the NMS consists of the following modules: configuration management, performance management, fault management, diagnosis and test, service observation, signaling tracing, security variable and charging management. 6.1 Configuration Management System The configuration management system provides user-friendly interfaces for the configuration and management of network resources. The configuration management system provides centralized configuration and management of the different kinds of NEs in GPRS/WCDMA/LTE such as the configuration and management of physical equipment, exchange and signaling, and at the same time, provides tools for data transmission, data backup and restore, and system initial configuration. Before data configuration, to guarantee the version has been correctly installed and can run normally, it is necessary to confirm the following data: Entity type of the local exchange, which is vgw here. Cabinet configuration of the local exchange. Resource number segment allocation of the local exchange, such as GTP-C and GTP-U number resources. Service address configuration of the local exchange, including address configuration for the signaling plane processing unit, user plane processing unit and IP forwarding unit. ZTE Confidential & Proprietary 43

46 The APN configuration of the local exchange, including address pool configuration. Forwarding address segment configuration of the local exchange office. Router configuration of the local exchange, which is performed at the S11 interface of the vgw via telnet. 6.2 Alarm Management System The alarm management system consists of two parts: real-time display of current alarms and alarm-related operation. The function is to display the current alarms of the device, communication, service and processor on interfaces and list the detailed information about each alarm, such as alarm source, alarm level, alarm time, alarm content, alarm cause, alarm type and additional information for your attention. 6.3 Performance Management System The performance management system provides statistic data about some performance parameters and traffic data of the mobile system for reference by operation departments. The maintenance terminal flexibly defines performance measurement. A performance measurement job includes the start/end time, days of duration, measurement object set and granularity period. The maintenance terminal allows operator to generate, delete, modify and observe the performance measurement in real time. The performance measurement has a wide coverage, ranging from traffic and signaling performances, service quality measurement, network configuration verification, availability measurement, throughput measurement and switching function measurement. 6.4 Diagnosis Test system The diagnosis test system, a part of fault management, provides routine test and immediate test functions for PS domain devices of the core network, to ensure normal 44 ZTE Confidential & Proprietary

47 and stable operation of the entire system. In daily maintenance, the diagnosis test system is used to test the physical devices and communication links through routine test. If the test result is likely to be abnormal, the system alerts the engineering personnel to pay attention and take proper measures to prevent fault from taking place. In case of any fault, the diagnosis test system helps the engineering personnel find the fault cause and locate the fault quickly with the immediate test function to remove the fault as soon as possible. This system could also be used by the engineering personnel to judge whether the equipment and even the entire system have resumed normal operation. The ZXUN vgw system adopts a multi-module & fully distributed control structure. Each module consists of a series of basic units. The diagnosis test function is divided into intra-module test and inter-module test. The intra-module test is used to test the functions of the component units of the module, links between the units and MPs. And the inter-module test is used to test the communication of the adjacent modules. 6.5 Signaling Tracing System The signaling tracing system is used to trace the signaling data of the network operation and analyze the service operation. It comprises packet domain signaling tracing. GTP signaling tracing of the vgw covers: Tracing and displaying GTP signaling in real time. Displaying signaling details. Providing daily maintenance tools for data maintenance, such as tools for sorting, filtering, searching and deleting the signaling tracing records. Providing tools for reestablishing the database table when installing the database table for the first time or when the database table is damaged. Creating a new database table for signaling tracing. ZTE Confidential & Proprietary 45

48 6.6 Service Observation System The service observation system, as a part of the O&M system, is used to view the service operation status of the NEs and conduct analysis and processing accordingly. 6.7 Variable Management System The security variable system is used to maintain the service parameters that require dynamic modification. Currently, the parameters to be maintained are system control parameter, packet domain NE configuration parameters, authentication parameters and charging parameters. The security variable functions allow modifying data at the background and transferring modified data to foreground to synchronize the background data to foreground, to achieve flexible service parameter configuration. The security variable system is used to configure the following parameters: System control parameters Security parameters GTP control parameters 46 ZTE Confidential & Proprietary

49 7 Reliability Design 7.1 MTBF and MTTR analysis ZTE proposed virtualization SAE-GW solution can provide 99,999% availability for all the proposed applications. The availability of virtualization can be described through compared with traditional architecture. U U U U U U n n PNF HW HW HW HW HW HW The reliability of physical components of PNF(Physical network function) is guaranteed by the redundancy modes such as active/standby and load balancing. VNF U 1 V M U 2 V M U 1 V M U n V M U n V M U 2 V M VMM VMM VMM VMM HW HW HW HW ZTE Confidential & Proprietary 47

50 The SW components also support active/standby and load balancing. In addition, VM supports migration and rebirth. Servers also have redundant configuration. PNF and VNF have the same reliability model, so their reliability is compared according to their PM/VM components VM uses COTS HW and virtualization layers. MTBF is reduced. MTTR But the virtualization layer supports VM migration and rebirth, which will reduce MTTR. When MTTR falls more than MTBF, VM s reliability is higher than PM s. 7.2 Reliability Analysis In the NFV environment, the reliability analysis can be divided into two distinct parts: the server part and the network connections part, where the network part is to connect all the servers. This can be illustrated in the following diagram: Figure 7-1 NFV Reliability Model 48 ZTE Confidential & Proprietary

51 Obviously, the overall system availability is A s A N, where A s is the server part the availability and the A N is the network part of the availability. For any given network availability, both the server part and the network part availability need to be better because both A s < 1 and A N < 1. For the network part, the availability will also depend on the number of the hops. If A n is the denote the availability of the network element, for a vswitch with maximum of h hops, the availability of the vswtich would be A h n. Hence, considering the 1+1 configuration of the vswtich, the A N can be given by A N = 1 (1 A n h ) 2 In numerical terms, the following table illustrates the network part of the availability as a function of vswitch hops and per network element availability Network Element Availabil ity/hop ZTE Confidential & Proprietary 49

52 The challenging part of the system availability is actually in the server part. While closed solution for ideal case is available, the ideal case does not reflect the reality of using COTS hardware. In order to evaluate the effect of using COTS hardware, including site issues such as site maintenance and site failure, ZTE performed a large amount of simulations with the following factors being considered: Silent Error: Silent error represents the source of error that can t be identified and, if it happens on the master part of the protection group, the data would be corrupted and the enire protection group goes through a service affecting downtime. Site Maintenance Time: Site maintenance will be performed if there is no error inside the network. The site maintenance represents a unique aspect of using COTS hardware. Site Failure: A site failure, albeit with lower probability, is also simulated by the discrete event simulator. The simulation evaluates the impact of one or two backups. The result for the single backup system can be shown as follows: Figure 7-2 Availability vs Silent Error vs Server Availability - Single Backup 50 ZTE Confidential & Proprietary

53 The following table presents precise information regarding this simulation results. Silent Error/Server Availability As evidenced in the table above, the server part of the system availability will be impacted by the silent error and a single redundant hardware will only provide marginal improvement when the silent error probability is small. The result for dual-backup is shown in the following figure: ZTE Confidential & Proprietary 51

54 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4 0,45 0,5 0 ZXUN xgw Product Description (vgw) Figure 7-3 Availability vs Silent Error vs Server Availability - Dual Backup Availability v.s. Silient Error v.s. Server Availability (dual backup) The diagram above shows a general trend in the system availability and the following table provides precise data: Silent Error/Server Availability From the tables for single and dual backup, we can see that dual backup only provides marginal benefit during site failure events. Given the fact that site failure events are inevitable in practice, a geographically distributed single backup system is recommended for simplicity. 52 ZTE Confidential & Proprietary

55 In conclusion, we make the following statements regarding using COTS hardware for achieving telecom grade reliability: It is possible to use COTS hardware to support telecom grade reliability, even with unique features of COTS hardware It is important to have the virtualization management system to report detailed hardware information to the VNF mangers in order to reduce the silent error probability. 7.3 Physical Failure Recovery When detecting a hardware failure or removing the hardware that causes system crashing, the system supports re-creating a VM to give it a rebirth in a different place. The service data that is stored in a shared storage can be reloaded to avoid data loss. In addition, the network configuration a VM can also be restored to avoid service interruption. ZTE Confidential & Proprietary 53

56 7.4 Hypervisor Failure Recovery When the system detects Hypervisor software exceptions of a computing node, it tries to originate VM hot migration. If the migration is successful, it tries to reset or reinstall the computing node to restore it. If the migration is failed, the system resets the computing node and meanwhile re-creates it in a different place, keeping the original storage and network resources for VMs. 7.5 VM Failure takeover vgw is composed of several nodes; here the node means the actual Virtual Machine (VM). The redundancy modes between nodes (Virtual Machines) include 1+1 active/standby, N+1 mutual hot backup, and load balancing. The synchronization of user data and session data between active and standby VMs is implemented as follow: 54 ZTE Confidential & Proprietary

57 Regarding the registered user data, after the user registers successfully, the active VM synchronizes the user data to the standby VM; in case of user re-registration, the active VM also synchronizes the changed data the standby VM; in case of user de-registration, the active VM deletes the user data and notifies the standby VM to do so. Regarding the session data, after the session is established successfully, the active VM synchronizes the session data to the standby VM. After the session is released, the active VM deletes the session data and notifies the standby VM to do so. 1+1 active/standby One node is active. The other node is standby, which will take over the traffic if the active is failed. 1+1 hot/standby One node is active. The other node is standby and simultaneously synchronizes the real-time data from the active node. If the active node is failed, the hot standby node will take over the traffic timely, and keep the service continuity. Hot-standby mode requires data synchronization between the active and standby nodes. N+1 mutual hot backup N+1 nodes serve as mutual backup for each other. If one node is failed, the other nodes will share and take over the traffic of the failed node. Hot-backup mode requires data synchronization between mutual nodes. Load balancing Several nodes share traffic to balance the load. If one node is failed, the rest will take over the traffic without data synchronization. To keep high availability and reliability, the workflow is showed as below figure: ZTE Confidential & Proprietary 55

58 vgw Active VM (GSU) Backup VM (GSU) Backup VM (LBU) Active VM (LBU) Service Access Service Access synchronizes data synchronizes data synchronizes data synchronizes data Take over the traffic Take over the traffic Service Access Service Access In case of normal status, the active VM handles the service access, and always synchronizes subscriber data and conversation data to the standby one. If the active VM is out of service due to SW or HW fault, the backup one will take over the total traffic handled on the active one without impact on active users. 8 Networking The ZXUN vgw is a functional entity for connecting the PS network to the PDNs. It features a simple networking mode. In the PDN, it has the same location as a router to allow the access to subscriber. The ZXUN vgw provides flexible configuration. The national backbone EPS network comprises several regional nodes that are connected to each other in mesh. A pair of top-level Domain Name Servers (DNS) is set on the national network, responsible for domain names that cannot be analyzed by the provincial DNS. The provincial networks access the backbone network nodes through Routers. Routers are usually deployed in pairs, for accessing different backbone nodes to ensure the network reliability. 56 ZTE Confidential & Proprietary

59 The logical structure of the national backbone network is shown in the following figure. Figure 8-1 PS/EPS Backbone Network PS/EPS backbone network PS/EPS network in Site A Router Router PS/EPS network in Site B Router PS/EPS network in Site C When the EPS backbone network based on the national IP backbone network, no new routing device is necessary. But when it does not depend on the national IP backbone network, the regional nodes are connected through the dedicated line. There are multiple networking schemes for the provincial PS/EPS backbone network construction. When there is an IP backbone network in a province, the vgw serves as the node to access the IP backbone network. When there is no IP backbone network in the province, the provincial backbone network may have one or multiple backbone nodes according to the capacity at the beginning of the network construction. When the needs for the PS/EPS are not high and are centralized in only a few cities, the vgw and other NEs in these cities are usually connected through the LAN in order to reduce the cost and accelerate the network construction. In some local networks, there are only vgw but no MME or SGSN function. In this case, the provincial network accesses the national backbone network through the routers and the local networks are connected through the dedicated leased circuit. In a signaling network, the SGSN communicates with HLR through the SS7 network. This networking is simple in structure and provides the packet service throughout the province quickly. ZTE Confidential & Proprietary 57

60 If the need for the PS/EPS is high, there will be many backbone nodes in the province. The backbone nodes are responsible for service convergence in some areas and they are interconnected into a mesh network. The provincial backbone network is connected to the national backbone network. If there is an IP backbone network in the province, the MMEs are directly connected to the IP backbone network. The following configuration modes for the PS/EPS local network construction are available according to the PS/EPS volume. Mode 1: The SGSN/MME is needed in the local network, but the vgw is not needed. Mode 2: Multiple MME and vgw are needed in the local network. In Mode 1, only the MME is configured in the local network and different local networks share one vgw. In this case, the MME is only responsible for the EPS subscribers in the local network. The MME is connected to the outside through the provincial backbone nodes. In Mode 2, there is a great need for the EPS in the local network, so multiple MMEs/ vgws should be set. All the nodes could be placed together to connect each other through the LAN or placed separately through the MAN. At the initial stage of the EPS network construction, as the capacities of the MME and vgw are small, so they could be combined into one in structure (but they are two entities to outside). The combined MME provides WAN S11 and SGi interfaces for other MMEs and vgws, but uses an Ethernet interface for the local vgw. The S11 interface between the combined MME and vgw adopts the standard protocol. When combined, no separate cabinet should be set for the vgw. In this case, as the vgw capacity is small, the MME and vgw uses one router to connect the EPS backbone network or the external PDN. The networking structure of the vgw and the MME in the same LAN is shown in the following figure. Figure 8-2 Networking Mode of vgw and MME that are in Same LAN 58 ZTE Confidential & Proprietary

61 If the address pool mode is used or the IP address of the mobile phone is static, then the DHCP server is not necessary. In addition, the MME and vgw are both connected to the EPS backbone network. The independent networking mode is often used. In this mode, the vgw is connected to the MME or the other equipment through the EPS backbone network. ZTE Confidential & Proprietary 59