Cisco’s Medianet Performance Monitor (PerfMon) is a variation of Flexible NetFlow (FNF) that allows the user to become aware of key media and application metrics for traffic flows. This new capability reports not only on the standard NetFlow 5-tuple (Source IP Address, Destination IP Address, Source Port, Destination Port, and IP Protocol), but also on media specific data such as Jitter, Media Rate Variation, RTP Synchronization Source (SSRC), and much more. The main goal is to grant Network Administrators the chance to detect flow performance issues before they impact the overall usability of the media application.

LiveNX serves to provide a detailed view of the reported PerfMon traffic, with an easy to understand graphical interface. Users can then further leverage Cisco’s PerfMon technology, with the assistance of LiveNX, to perform troubleshooting and monitoring of critical voice and video traffic flows. This technical application note provides instructions on enabling and using PerfMon within the context of the LiveNX software.

Cisco Catalyst Switches

Cisco Integrated Services Routers (ISR) and Aggregation Services Routers (ASR)

Setting Up the Device

The first step to leveraging these capabilities is to add the devices to the LiveNX topology. This is accomplished through discovery, or by directly adding the devices through the File menu:

Then, step through the Add Device wizard entering the appropriate information for the IP address, SNMP read string, CLI login credentials, and select the appropriate interfaces:

Then enable NetFlow collection and configure any other polling options:

Here is the example topology we will be using for the commands:

LiveNX can assist in configuring Medianet on supported devices. The Configure Flow feature allows each device to be configured with the necessary commands.

Click Flow > Configure Flow or right click on a device in the device view and then selecting Flow > Configure Flow. This capability is available to Admin and Full-Config user roles.

After clicking on Flow > Configure Flow, LiveNX displays a Flow Configuration summary table listing all the devices discovered by LiveNX as well as its properties including Type, IP Address, Description, Tags, and several Flow Configuration Options.

Select the device(s) you wish to configure Medianet on by clicking the check box next to the device name and then click on Configure Selected.

Select the interfaces you wish to configure Medianet on with the check boxes under the Voice/Video Performance (Medianet) column. A hyphen mark in the column indicates that the device does not support Medianet.

Once all the selections have been made, the Save to Devices, Preview CLI, and Revert.

• Preview CLI – click on Preview CLI to review the commands that LiveNX will send to the device to re-configure flows on the selected interfaces. If configuring multiple devices, use the device table on the left to select a device in the list.

• Revert – click on Revert to return your flow configuration settings back to the initial state prior to any “Save to Devices” command.
• Back – click on Back to return back to the device only view of the flow configuration table.
• Close – close the flow configuration table.
• Save to Devices – LiveNX will ask you to confirm that you would like to configure the devices. If confirmed, LiveNX will modify the flow configuration for the selected interfaces on the device. A message will be generated to indicate successful re-configuration of that device or to indicate details on the errors encountered during the flow configuration.

NOTE: You can modify your Medianet Policy to add other Voice and Video applications to monitor. To do this for all of your devices that have Medianet, you only need to modify one seed policy and then push that policy to the rest of your devices.

First go to your seed device and find the “LIVEACTION-CLASS-MEDIANET” and then select your match type. Below the policy is being matched to Skype using NBAR2, but you can also use access-lists to be specific about your telepresence video conversations.

After modifying your policy, you can then select to copy that policy to your other Medianet capable devices.

Medianet Flow Alerts

LiveNX’s alert system affects the output of multiple views and reports in the application. Exceeding the threshold values under the Configure Alerts dialogue will trigger an alert in the In-Application Alerts window, and the corresponding flows will be highlighted in the Device View, System View, and Medianet Top Analysis Report. The following screenshots reflect the enabled alerts (percentage being greater than 1%).

System Flow Table

Under the Medianet tab, the System Flow Table will display PerfMon related statistics on the collected flows. The flows are an aggregation of all received flows handled by both the Traditional NetFlow process and the Medianet PerfMon process, with a new entry being uniquely identified by the collectable attributes of the packets. Some of the new packet attributes related to Medianet include:

• RTP SSRC = RTP Synchronization Source. A unique identifier used to differentiate stream sources using the same 5-tuple flow information.
• Packet Loss % = The largest packet loss % value received from all devices in the system during the polling period.
• Interarrival Jitter Mean = The largest RTP jitter mean value received from all devices in the system during the polling period.
• Loss Event Count = The sum of the Loss Event Counts received from all devices during the polling period.
• DSCP IPV6 Traffic = Medianet PerfMon reported DSCP value for the specific flow.

NOTE: Since the System Flow Table deals with aggregated data, some of the PerfMon fields are not displayed. The Device Flow Table includes a more detailed view of various PerfMon attributes.

Medianet Path Analysis

LiveNX can help quickly determine a problematic location with easy to understand color differentiation. Green indicates no issue while red will help determine an issue, like packet loss. It will also help in tracking down the path a conversation takes across the network.

Device Flow Table

LiveNX’s Device Flow Table only outputs device-specific Medianet flow data in contrast to the aggregated flow data displayed by the System Flow Table. This allows for a more in-depth view into the media flow and projects a wider range of flow metrics. Utilizing the configured alert threshold shows the offending media flow highlighted in pink, while the attribute is highlighted in red. The main purpose of the Device Flow Table is to provide real-time monitoring capability to the user.

Historical Playback

Another functionality specific to the Device View is the ability to perform Historical Playback on flows traversing the device. This is not limited to Medianet PerfMon flows, but also includes Basic Flows, AVC, Firewall, Wireless, PfR, and other unspecified flow types. Historical Playback provides the ability to inspect the changes to flow behavior within a given timeframe, with a scrollbar. The following screenshots represent the time period before and after the addition of RTP traffic into the network.

Medianet Reports

While the Device View displays real-time flow data, the Medianet Report section provides historical data on a specific device. The user can specify the various flow types and time periods for which to run the report. By default, a report for the last 15 minutes is selected, but a Custom time range can also be used which spans across multiple days, weeks, or even months.

NOTE: A larger time frame requires LiveNX to process more flows, which will take longer to process.

Other reports are also available for the user under the Medianet Reports section. This allows historical visibility for the Jitter/Loss and Round Trip Time related data for any specific device. Reports can also be scheduled, which allows for storage and email notification of reports in a centralized location. Both Time Series and Aggregation modes can be selected as well as flow direction.

Catalyst 3750/3560 Egress Interface Index

The Catalyst 3560/3750 platforms suffer from a known limitation which does not properly display the exit interface. This prevents LiveNX from properly drawing and connecting the flow lines between devices participating in PerfMon and is depicted by an Out IF value of Null0.

cat3560X-67_107#show performance monitor status | include (output|Match)
Match: ipv4 src addr = 192.0.2.35, ipv4 dst addr = 10.0.2.25, ipv4 prot = udp, trns src port = 3446,
trns dst port = 5004, SSRC = 2221342720
interface output : NA

Notes on Catalyst 3750/3560 NetFlow Operation

Performance Monitor imparts a CPU and memory performance impact. Test the impact for your specific environment in the lab before wide scale deployments. Performance Monitor impact depends on factors such as number of flows monitored and the complexity of the classification. As an estimate, you can budget about:

• 3% CPU utilization for every 200 flows
• 5 MB initial memory usage and about 3 MB for every 500 flows monitored

Cisco’s PerfMon is a helpful tool for Network Administrators in modern networks who are asked to deliver high-quality voice and video conversations. Using LiveNX to configure PerfMon simplifies the procedure for these capabilities. By leveraging PerfMon within LiveNX, an administrator is able to gain insight into key metrics via visualization and reporting that were previously unavailable.

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