PPPoE Intermediate Agent Testing with

Transcription

1 Agilent N2X PPPoE Intermediate Agent Testing with Agilent N2X Application Note

2 Introduction PPPoE intermediate agent functionality is described in the DSL Forum s TR-101 reference access network architecture. The function is normally performed by an Access Node (e.g, DSLAM) and its primary purpose is to add access loop identification information to the PPPoE discovery stage frames so that the Broadband Network Gateway (BNG) terminating the PPPoE sessions can associate the activity with a particular subscriber. PPPoE intermediate agent functionality is in many ways the equivalent to a DHCP relay agent using Option 82 in that it conveys subscriber identity to the BNG. PPPoE intermediate agent TAGs also contain information such as upstream and downstream data rates for the subscriber local loop. The BNG may use this information, along with subscriber identity to apply policies such as rate limiting or traffic shaping. Some key test challenges involving PPPoE intermediate agents include: 1. Functional testing the agents themselves, to ensure that they correctly insert the PPPoE TAGs with the appropriate subscriber information. It is also important to ensure that the TAGs are stripped from downstream control traffic destined for the subscriber. 2. Scalability testing of PPPoE intermediate agents to verify how many PPPoE sessions they can sustain and at what rate they can be established. 3. Testing BNG/PPPoE server behavior in the presence of PPPoE intermediate agents. This involves ensuring that the server is processing the subscriber identification information properly and applying the correct QoS/traffic shaping policies. As an example, the BNG may be required reject unknown subscribers, or shape traffic according to the subscriber port data rate. Test Objective This application note shows how N2X can be used to test: PPPoE intermediate agents themselves PPP servers in the presence of PPPoE intermediate agents Main Aspects to Learn PPPoE intermediate agent is supported on all N2X Ethernet interfaces, including 10 GbE PPPoE can be run concurrently with other access protocols N2X supports both PPP client (initiator) and server (responder) to surround an intermediate agent Equipment Required Chassis (e.g.,n5540a) Controller (e.g.,n5543d) Ethernet cable E7881B N2X Packets and Protocol Emulation Software E7888A Access Protocol Emulation Software License N2X Ethernet card (e.g.,n5551b) Note: The N5551B tri-rate Ethernet card has been used as an example throughout this Application Note. All settings and options refer to the ones available on the N5551B. 2

3 Device Under Test This application note uses a DUT acting as a PPP server in the presence of a PPPoE intermediate agent, although N2X is also well suited to testing the intermediate agent itself. Intermediate agents are normally Access Nodes (e.g., DSLAMs) whilst PPP servers are more typically BNG/B-RAS/EAR-type devices. Test Set-up Testing a PPP server in the presence of a PPPoE intermediate agent DUT Configuration: Configure the DUT to act as a PPP server on the N2X port emulating PPP subscribers. Be sure that the IP addresses assigned to the ports you will be using are correct and that no subinterfaces are created on those ports. 3

4 Set up the Emulation Port Setup Click Ports from the main window top tool bar. In the Port Selection dialog, select two test ports with type 10/100/1000 Ethernet. Click OK. Configure N2X Subscriber Port Click Emulation (located under Setup) from the main window side tool bar. Double-click on the line under the first port which reads <Double-click here to add Routing/Access protocol emulations.> In the New Emulations dialog, double-click on PPP and select PPPoE Client. Check the Options box (in the lower right-hand corner) with the description Edit properties after emulations added (see Figure 1). Click OK Figure 1: Add a PPPoE client emulation On the General tab of the PPPoE Client Properties dialog, set the Count (located in the Device section) to 5. This means 5 subscribers will be emulated. On the PPPoE tab of the PPPoE Client Properties dialog, check the Agent Circuit ID and Agent Remote ID boxes (see Figure 2). Click the button in the Access Loop Characteristics field (see Figure 2). In the Access Loop Characteristics dialog, check the Actual Data Rate Downstream Sub-Tag box (i.e. the second sub-tag listed). Click the + icon to expand the tree node and view the default values for this field. If configured, the DUT will rate-limit traffic to subscribers according to these values. Click OK. Check the Access Loop Encapsulation box and leave the default setting of: Data link = Ethernet, Encapsulation 1 = Untagged Ethernet, Encapsulation 2 = NA (see Figure 2). 4

5 Figure 2: Configure the PPPoE Intermediate Agent Parameters Click OK to apply the settings to close the PPPoE Client Properties dialog. In the Setup-Emulation view, check the box beside the PPPoE Client to enable it. Configure N2X Core Port Click Link Layer (located under Setup) from the main window side tool bar. On the Ethernet tab of the Link dialog, click on the LAN/VLAN Addresses button. Disable ARP on the first port by un-checking the ARP box. Edit the existing address pool on the second port. In the LAN/VLAN IPv4 Address Pool dialog, configure the SUT IP Address to match the IP address of the core-facing port on the router and set Num Addresses to 1. Send the ARP request. Close the LAN/VLAN IPv4 Addresses dialog. On the Ethernet IPv6 tab, disable all NDP links. Configure Downstream Traffic 20. Click Traffic and then select Group by mesh (both located under Setup) from the main window side tool bar. Selecting Group by Mesh is not necessary for creating the traffic mesh, but it allows you to easily view all of the stream groups created by the mesh. 21. Click on the arrow beside the New button in the Setup-Traffic tool bar. Select Device Mesh (see Figure 3). 5

6 Figure 3: Create a Device Mesh By default, the traffic orientation for the device mesh is unidirectional. To configure bidirectional traffic, select the Bidirectional radio button on the General tab of the New Device Traffic Mesh dialog. This is not required for this test though Go to the Sources and Destinations tab of the New Device Traffic Mesh dialog. Set the Available Sources Type to Port and select the second port. Click Add Source. Set the Available Destinations Type to Device and select PPPoE Client. Click Add Destination (see Figure 4). Figure 4: Configure the Device Mesh 25. Click OK to apply the settings and close the dialog. 6

7 Establish the PPP Sessions 26. Start capture. 27. In the Setup-Emulation view, select the PPPoE Client, click Actions PPPoE client and select Open Connections. The PPPoE Client state should go to Established. 28. Stop capture. View Results and Verify DUT Behaviour 29. With the PPPoE Client selected, click Details. 30. On the Instances tab of the PPPoE Client Instance Details dialog, click Columns. 31. In the Choose Columns dialog, select Agent Circuit ID and Agent Remote ID. Click OK. From the Choose Columns dialog, you can also add columns to display statistics, state, and timing data for individual PPP sessions. To view the aggregated statistics for all of the PPP sessions within the PPPoE Client emulation, click Results from the Setup-Emulation tool bar. 32. Using the PPPoE Client Instance Details dialog, compare the DUT s list of subscriber identifier data (session ID, local IPv4, agent circuit ID, agent remote ID) with each device instance emulated by N2X to ensure they match (see Figure 5) Figure 5: View Individual Session Data Go to the Setup-Capture view and look at the captured packets. The PPPoE discovery packets received from the DUT should not contain the Vendor-Specific tag (as specified by R-116 in TR-101). In the Setup-Traffic (Group by Mesh) view, select the traffic mesh and click on the Refresh icon from the Setup-Traffic tool bar, and then click YES on the pop-up dialog. This will update the traffic mesh s stream groups with the MAC addresses, session IDs, and IP addresses learned/ negotiated during the PPP session establishment. Double-click on the stream group, and accept the default to view the stream group as Stream group properties. On the Packet Template tab of the TrafficMesh Properties dialog, navigate to the Destination Address field in the IPv4 header and set Stream IDs to YES. This will create a separate stream for each PPP session (see Figure 6). Click OK. 7

8 Figure 6: Configure the Stream Group to contain a Stream for Each PPP Session Click Realtime (located under Results) from the main window side tool bar. Click Setup from the Results-Realtime tool bar. On the Streams tab of the Setup Measurements dialog, multi-select the traffic streams and click the Add to Measurement Table button (see Figure 7). If you click on the checkbox button, you will see the boxes under the Table column are checked Figure 7: Add the Streams to the Measurement Results Table Close the Setup Measurements dialog. The Results-Realtime view shows the streams displayed under the second port. Start traffic by clicking on Traffic from the main window top tool bar. The DUT should shape the downstream traffic to the DSL service rate. The measurements, taken in Step 42 to 44 verify this. 42. In the Results-Realtime view, look at the Rx Test Throughput column. The receive rate for each stream should be less than or equal to the rate in the access loop characteristic sub-tag (Actual Data Rate Downstream) configured in step Change the Results-Realtime view to show cumulative results by clicking the S button. 44. Look at the Rx Packet Loss column for the streams. There should be no packet loss (see Figure 8). 8

9 Figure 8: View Results Other test scenarios are dependent on the PPPoE intermediate agent functionality that the DUT supports. Here are some examples: Service Refusal: Configure the DUT to deny services to specific access loops (which are identified by the Agent Circuit ID). Configure the Agent Circuit ID in the N2X PPPoE Client emulation such that some of the sessions will use IDs that match those being denied service by the DUT. Use the Instance Details dialog to verify that only some sessions are established the ones with Agent Circuit IDs that are not being denied services by the DUT. IP Address Assignment: Configure the DUT to assign certain ranges of IP addresses to specific access loops. Configure the N2X PPPoE Client emulation to use Agent Circuit IDs that match these access loops as well as IDs that don t. After the PPP sessions are established, view the Instance Details dialog to verify that the appropriate IP address is assigned to each PPPoE client (i.e. device instance), based on its Agent Circuit ID. 9

10 Appendix Testing a PPPoE Intermediate Agent A PPPoE intermediate agent is implemented in an access node such as a DSLAM. To test the device, surround it with an N2X client and server: Add two ports to the N2X test session. Connect one port to the DSLAM via a switch and DSL CPEs, and then add a PPPoE Client emulation to the port. This configuration is required since N2X does not have DSL interfaces. Connect the other port directly to the DSLAM uplink, and add a PPP over Ethernet Peer emulation (found under the PPP Legacy emulation type) to the port. In the PPP Over Ethernet Peer Properties dialog, set the Mode to Respond to Incoming Calls. This makes the emulation act like a server. Things to test include: Verify that the DUT (i.e., access node) adds PPPoE intermediate agent tags to the upstream PPPoE discovery packets. If the PPPoE discovery packets sent by the (N2X-simulated) clients already contain intermediate agent tags, the DUT should replace these tags. If the PPP server includes intermediate agent tags in its downstream PPPoE discovery packets, the DUT should remove these tags before forwarding the packets to the PPP clients. 10

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12 Agilent N2X Agilent s N2X multi-service tester combines leadingedge services with carrier grade infrastructure testing and emulation. The N2X solution set allows network equipment manufacturers and service providers to more comprehensively test new services end-to-end, resulting in higher quality of service and lower network operating costs. Warranty and Support Hardware Warranty All N2X hardware is warranted against defects in materials and workmanship for a period of 1 year from the date of shipment. Software Warranty All N2X software is warranted for a period of 90 days. The applications are warranted to execute and install properly from the media provided. This warranty only covers physical defects in the media, whereby the media is replaced at no charge during the warranty period. Software Updates With the purchase of any new system controller Agilent will provide 1 year of complimentary software updates. At the end of the first year you can enroll into the Software and Suport Agreement (SSA) contract for continuing software product enhancements. Support Technical support is available throughout the support life of the product. Support is available to verify that the equipment works properly, to help with product operation, and to provide basic measurement assistance for the use of the specified capabilities, at no extra cost, upon request. Ordering Information To order and configure the test system consult your local Agilent field engineer. Sales, Service and Support United States: Agilent Technologies Test and Measurement Call Center P.O. Box 4026 Englewood, CO Canada: Agilent Technologies Canada Inc Matheson Blvd. E Mississauga, Ontario L4W 5M Europe: Agilent Technologies European Marketing Organisation P.O. Box AZ Amstelveen The Netherlands (31 20) United Kingdom Japan: Agilent Technologies Japan Ltd. Measurement Assistance Center 9-1, Takakura-Cho, Hachioji-Shi, Tokyo , Japan Tel: (81) Fax: (81) Latin America: Agilent Technologies Latin American Region Headquarters 5200 Blue Lagoon Drive, Suite #950 Miami, Florida U.S.A. Tel: (305) Fax: (305) Asia Pacific: Agilent Technologies 19/F, Cityplaza One, 1111 King s Road, Taikoo Shing, Hong Kong, SAR Tel: (852) Fax: (852) Australia/New Zealand: Agilent Technologies Australia Pty Ltd 347 Burwood Highway Forest Hill, Victoria 3131 Tel: (Australia) Fax: (61-3) Tel: (New Zealand) Fax: (64-4) This information is subject to change without notice. Printed on recycled paper Agilent Technologies, Inc Printed in USA November 7, EN