Configuring VPN ID in Flexible NetFlow Multiple VPNs from the same private network can use same private source and destination IPs in the data traffic. This can make it difficult to identify the IP address to which the data belongs. A VPN-ID can be used to solve this issue. A VPN-ID is a global unique Virtual Private Network Identifier. It is used to identity a VPN across autonomous Systems (AS). If VPN-ID is exported in NetFlow exported packets – the collector in another AS will be able to associate and segregate the flows based on the VPN to which the data belongs. VPN-ID is a system level property similar to VRF-ID and it can be exported in a similar fashion.
Components of the VPN ID Each VPN ID consists of the following elements: • An Organizational Unique Identifier (OUI), a three-octet hex number. The IEEE Registration Authority assigns OUIs to any company that manufactures components under the ISO/IEC 8802 standard. The OUI is used to generate universal LAN MAC addresses and protocol identifiers for use in local and metropolitan area network applications. For example, an OUI for Cisco Systems is 00-03-6B (hex). • A VPN index, a four-octet hex number, which identifies the VPN within the company. You can configure the VPN ID by using the vpn id command in VRF definition configuration mode. Specify the VPN ID in the following format:
vpn id oui:vpn-index Once the VPN ID has been configured you can use the option vrf-attributes command in flow-exporter configuration mode to configure the VPN ID. How to Configure Flexible Netflow To configure Flexible Netflow, follow these general steps: 1. Create a flow record by specifying keys and non-key fields to the flow. 2. Create an optional flow exporter by specifying the protocol and transport destination port, destination, and other parameters. 3. Create a flow monitor based on the flow record and flow exporter. 4. Create an optional sampler. 5. Apply the flow monitor to a Layer 2 port, Layer 3 port, or VLAN.
Creating a Flow Record Perform this task to configure a customized flow record. Customized flow records are used to analyze traffic data for a specific purpose. A customized flow record must have at least one match criterion for use as the key field and typically has at least one collect criterion for use as a nonkey field. There are hundreds of possible permutations of customized flow records. This task shows the steps that are used to create one of the possible permutations. Modify the steps in this task as appropriate to create a customized flow record for your requirements. Configuring Flexible NetFlow Configuring VPN ID in Flexible NetFlow Configuring Flexible NetFlow 20