Mobile Backhaul Network Testing Solutions

MPLS-TP (MPLS Transport Profile) based on MPLS technology combines the characteristics of Ethernet and connection-oriented technology, becoming the technical implementation solution for 3G/4G mobile backhaul networks. Spirent Communications' Mobile Backhaul test solution based on L2~L7 integrated network test platform Spirent TestCenter and network damage tester ANUE tests mobile backhaul networks based on MPLS, T-MPLS and MPLS-TP from the above five aspects , including protocol functions/scalability/protocol and data performance.

2 Performance and QoS Testing

The Metro Ethernet Forum (MEF) defines a series of standards to regulate Ethernet with quality of service assurance. These standards include: MEF6 defines point-to-point (E-Line) and multipoint-to-multipoint (E-LAN) Ethernet services (Ethernet Services); MEF10 defines the parameters of Ethernet services, including bandwidth parameters (Bandwidth Profile), performance parameters (Performance Profile, i.e. QoS level), frame transmission parameters (Frames Delivery), etc.; MEF9 standard tests whether the Ethernet services or devices deployed on the UNI meet the definitions of MEF6 and MEF 10. This specification mainly defines the basic functional test of Ethernet Service; MEF14 standardizes the test of traffic management (MEF10 definition), including performance, QoS, traffic regulation and other aspects. This specification defines the traffic performance test on Ethernet Service.

Spirent TestCenter can generate the industry's highest 32768 independent test streams on one test port. Each test stream can define independent protocol headers, payloads, labels, and QoS parameters. In terms of Mobile Backhaul performance testing, each port can support 32k independent EVC tests. Due to the high port density of the test card, Spirent Testcenter can generate telecom-class metropolitan Ethernet services and verify the number of EVCs supported by the device or network, which is very suitable for scalability testing. It can generate point-to-point, multipoint-to-multipoint, and full-mesh test traffic topologies, and fully verify various Ethernet Services such as E-Line and E-LAN. MEF9 and MEF14 test suites are provided. Spirent TestCenter is a standardized test instrument for MEF certification testing.

In terms of statistics, Spirent TestCenter can analyze 65,535 independent test streams (Stream) per port in real time, and provide more than 50 statistics for each stream in real time, including the total number and rate of received/sent frames, packet loss, delay, delay distribution, jitter, jitter distribution, various types of error packets, etc. that comply with the MEF10 definition, and provides flexible result filtering methods to help users record and find results comprehensively, quickly and flexibly during testing.

In addition, Spirent TestCenter provides an automated test suite for complex business service level agreement (SLA) testing. In the test suite, users can define many indicators such as packet loss, latency, jitter, order/disorder, and their logical combination SLA parameters. Figure 1 is a screenshot of the test result display method.

Spirent TestCenter can test a single device or a network. Figure 2 is a schematic diagram of the Spirent TestCenter network performance test scenario.

Figure 1 Network test scenario diagram

3 MPLS-TP Protocol Test

MPLS-TP is an Ethernet transmission network technology jointly defined by IETF and ITU-T. Based on the MPLS technical framework, MPLS-TP has made some optimizations for the characteristics of the transmission network. Table 1 lists the technical requirements of MPLS-TP and the differences between traditional MPLS.

Spirent TestCenter MPLS-TP test solution provides comprehensive testing capabilities for MPLS-TP protocol functions, performance, and scalability.

Table 1 MPLS-TP technical requirements

(1) Data plane: Spirent Testcenter supports all MP-TP and traditional MPLS forwarding function, performance, QoS testing and benchmark performance testing standards.

(2) Control plane: Spirent Testcenter supports static PW and LSP establishment and dynamic PW and LSP establishment through protocols. In dynamic control plane testing, Spirent Testcenter supports T-LDP PW establishment test and GMPLS LSP establishment test. In addition, Spirent Testcenter supports MS-PW.

(3) OAM: Spirent Testcenter supports OAM for LSP, PW (Path, Section), including MS-PW, LSP Ping, Traceroute, MPLS BFD, VCCV CC/CV, BFD over VCCV, PW Control Word and other OAM functions. In addition, Spirent Testcenter supports GAL/G-Ach encapsulation, OAM over GAL/G-Ach, and Y.1731 OAM over G-Ach for MPLS-TP nodes.

(4) Protection: Spirent Testcenter supports PW Redundancy (Status TLV) and PSC (MPLS-TP APS) protocol for linear protection testing. In terms of trigger conditions, Spirent Testcenter supports MPLS BFD, BFD over VCCV, and OAM trigger testing of PSC.

4 OAM protocol testing

OAM (Operations Administration and Maintenance) is a tool for monitoring and solving network problems. It can report the status of the network, allowing network administrators to manage the network more effectively. Ethernet OAM mainly includes the following aspects:

(1) IEEE 802.1ag and ITU-T Y.1731: Connectivity Fault Management, providing end-to-end Ethernet management.

(2) IEEE 802.3ah: Provides point-to-point link fault detection, also known as Link OAM.

Spirent TestCenter is the industry's first and most complete 802.1ag/Y.1731 and 802.3ah test solution. Spirent TestCenter provides a powerful 802.1ag/Y.1731 test configuration wizard to help users quickly simulate complex carrier Ethernet topologies and verify the CFM functions and performance of the devices and networks under test.

●Supports IEEE 802.1ag and Y.1731 CFM protocol simulation to verify the functions and performance of the devices and networks under test.

● Each port supports simulation of 12288 MPs and 1024 MA/MEGs. Each MEP can carry up to 253 MIPs and form different complex network topologies to test the ability of the device under test to act as a MEP and MIP.

●Provides a test configuration wizard and can preview the simulated topology structure, which can be saved as a picture file.

●Support OAM functions such as Loopback, CC, Link Trace, AIS, RDI, LM, DM LCK, etc.

●Users can define MAC Addresses, VLANs, MEG IDs/MAIDs, MEP IDs, levels and various TLVs.

● Provide detailed statistics based on ports, MP and MA/MEG, including the number of OAM messages sent and received, statistics of various alarms, and peer status.

●Support consistency testing.

●Support Y.1731 for MPLS-TP: Draft-bhh-mpls-tp-oam-y1731-04.txt.

5 Synchronous testing

Clock synchronization is an important part of MBH. If the clocks between base stations are out of sync, it will cause problems such as dropped calls, seriously affecting service quality. IEEE 1588v2 and Sync-E provide Ethernet-based clock synchronization for the entire network.

Spirent TestCenter provides the most comprehensive 1588v2 test solution in the industry. Spirent Testcenter can simulate Master or Slave clocks. Its testing capabilities include:

(1)Support 1588v2 over Ethernet and 1588v2 over UDP encapsulation.

(2) Supported PTP messages include:

●Event: Synch, Follow-up, Delay Request, Delay Response.

●General: Announce, Follow-up.

(3)Supports both Unicast and Multicast modes.

(4) High-precision timestamp based on FPGA.

(5)PTP Specific Results: Synchronization Status, Current Time, Delta Time, etc.

(6) Integrate with other L2~L7 protocols and services to perform integrated control and data plane testing.

(7)GrandMaster Redundancy/Failover test.

(8)Client Holdover test.

(9)Master to Client scalability test.

(10)1588v2 protocol decoding analysis.

Figure 3 shows a typical 1588v2 test scenario in Spirent TestCenter.

Figure 3 Typical 1588v2 test scenario

1588v2 devices usually have high synchronization accuracy in laboratory environments, but in live network environments, there are factors such as delay and jitter. Therefore, in addition to the usual functional and performance tests in the laboratory, it is necessary to simulate the damage model of the real network to verify the clock synchronization accuracy and fault tolerance of the device in the real environment. Spirent Communications ANUE network simulator can bidirectionally simulate a variety of network damage models such as packet loss, delay, jitter, disorder, repetition, bit error, cumulative burst, frame content modification, bandwidth speed limit, etc., which can provide a variety of real network damage models for 1588v2 testing in the laboratory. Figure 4 is a 1588v2 integrated test model.

Figure 4 1588v2 integration test model

Sync-E transmits clock information efficiently and reliably between nodes through the Ethernet physical layer. Sync-E supports the Synchronization Status Message (SSM) algorithm through the Ethernet Synchronization Messaging Channel (ESMC) to select the optimal clock. Spirent Testcenter supports ESMC/SSM protocol simulation testing. Its main capabilities include: supporting multi-clock simulation on one port and scalability testing; supporting Option1 (Based on 2048kbit/s) and Option2 (Based on 1544kbit/s); supporting 0x0-0xF QL value configuration; supporting SSM rates of 0~20 Message/s; supporting ESMC extended TLV definition and editing; supporting Sync-E protocol startup and termination; supporting dynamic modification of QL and SSM rate configuration; supporting internal crystal array clock source and external clock source; supporting basic ESMC/SSM protocol function and implementation testing; supporting clock selection testing; supporting clock distribution path verification testing; supporting clock fault switching (Failover) testing under various faults; supporting the generation of erroneous SSM messages, or at a rate of more than 10message/s (Slow The ESMC/SSM protocol and other MBH protocols (such as MPLS-TP protocol simulation, OAM protocol simulation, voice and video and other real application business simulation, etc.) can be simulated on one port to perform comprehensive integrated system testing under simulated real network conditions (see Figure 5).

Figure 5 ANUE MEF18/G.8261 test topology

6 CES performance test

In order to protect the user's existing investment in TDM equipment, it is necessary to provide TDM service access and TDM data transparent transmission capabilities in the next generation packet switching network. In addition, MEF has also launched MEF18 certification as a consistency test specification for TDM services on Ethernet.

Spirent Communications' ANUE network impairment simulator provides MEF18 and G.8261 test suites. ANUE simulates packet loss, delay, packet jitter, packet duplication, packet error, bandwidth limitation and other functions at L1~L7. Its main features include: providing bidirectional 100% full line rate performance impairment; supporting delay impairment simulation that varies with time, and providing delay impairment accurate to 1 bit; having real-time data statistics and alarm display; having 16 filters, which can generate impairments according to user needs through AND or combination; providing an editable range of 2000 bytes; providing the function of capturing and replaying existing network impairments; and providing G.1050 standard impairment templates.

ANUE's CES test function has the following features:

(1) Full compliance with MEF18/G.8261 specifications: With the help of replicable network models, MEF18 and G.8261 test suites are provided for MEF18 certification testing and G.8261 testing. The test scripts fully comply with MEF18/G.8261 specifications.

(2) PDV analysis provides a basis for IEEE 1588v clock accuracy analysis.

(3) Simulate various real network scenarios to verify the IEEE 1588v2 clock accuracy under existing network conditions.

7 Conclusion

Ethernet MBH is being deployed at an increasingly rapid pace. How to comprehensively evaluate MBH Ethernet devices and networks in various stages such as R&D, verification, engineering construction, and operation and maintenance has become a very urgent issue. Spirent Communications' MBH test solution fully supports testing from aspects such as transmission, service, and management. It is currently the most complete MBH test solution in the industry and is helping a large number of manufacturers and operators to complete the deployment of next-generation networks and services.