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Example: Sampling Instance Configuration

You can configure active sampling using a sampling instance and associate that sampling instance to a particular FPC, MPC, or DPC. In addition, you can define multiple sampling instances associated with multiple destinations and protocol families per sampling instance destination.

Example Network Details

The following example shows the configuration of two sampling instances on an MX480 router running Junos OS Release 9.6.

Figure 1: Active Flow Monitoring—Sampling Instance Configuration Topology DiagramActive Flow Monitoring—Sampling Instance Configuration Topology Diagram

In Figure 1, packets from Router 1 arrive on the monitoring router's Gigabit Ethernet ge-0/1/0 interface, the packets are sampled by the services interface sp-2/0/0 and sent to the cflowd server by the export interface ge-1/0/4. Packets from Router 3 arrive on the monitoring router’s Gigabit Ethernet ge-3/1/0 interface, the packets are sampled by the services interface sp-2/1/0 and sent to the cflowd server by the export interface ge-1/0/4. Normal traffic flow from ge-0/1/0 and ge-3/1/0 to ge-1/0/0 and on to Router 2 continues undisturbed during the sampling process. In active flow monitoring, both the input interface and exit interface can be any interface type (such as SONET/SDH, Gigabit Ethernet, and so on).

Only one sampling instance can be attached to an FPC, MPC, or DPC. Multiple families can be configured under a sampling instance. Each family can have its own collector address. You can define sampling instances and attach each instance to different FPCs, or a single sampling instance can be attached to all FPCs.

The sampling configuration for this example includes the following:

  • Two sampling instances, s0 and s1, configured to collect sampling data at the [edit forwarding-options] hierarchy level. The flow-server statement includes the IP address, port, and template of the flow server. The interface statement includes the services interface, sp-2/0/0 or sp-2/1/0, for flow record processing, and the source address of the incoming router on the sampled interface.

  • The binding of the two sampling instances to FPCs 0 and 3. These are configured with the sampling-instance statement at the [edit chassis fpc slot] hierarchy level.

  • Sampling activated on the input interfaces ge-0/1/0 and ge-3/1/0 using the sampling statement at the [edit interfaces interface-name unit unit-number family family] hierarchy level.

In this example, the ping command is issued on Router 1 to Router 2 via the MX480 router to generate traffic. After the packets are generated, show commands are issued to verify that the sampling configuration is working as expected.

Example Router Configuration

The following output shows the configuration of an MX480 router with two sampling instances.

Configuration Commands Used for the Configuration Example

The following set commands are used for the configuration of the sampling instance in this example. Replace the values in these commands with values relevant to your own network.

  • set chassis fpc 0 sampling-instance s0

  • set chassis fpc 3 sampling-instance s1

  • set interfaces ge-0/1/0 unit 0 family inet sampling input

  • set interfaces ge-0/1/0 unit 0 family inet address

  • set interfaces ge-1/0/0 unit 0 family inet address

  • set interfaces sp-2/0/0 unit 0 family inet

  • set interfaces sp-2/1/0 unit 0 family inet

  • set interfaces ge-3/1/0 unit 0 family inet sampling input

  • set interfaces ge-3/1/0 unit 0 family inet address

  • set forwarding-options sampling instance s0 input rate 1

  • set forwarding-options sampling instance s0 input run-length 0

  • set forwarding-options sampling instance s0 family inet output flow-server 198.51.100.2 port 2055

  • set forwarding-options sampling instance s0 family inet output flow-server 198.51.100.2 version9 template v4;

  • set forwarding-options sampling instance s0 family inet output interface sp-2/0/0 source-address 192.168.1.1

  • set forwarding-options sampling instance s1 input rate 1

  • set forwarding-options sampling instance s1 input run-length 0

  • set forwarding-options sampling instance s1 family inet output flow-server 198.51.100.2 port 2055

  • set forwarding-options sampling instance s1 family inet output flow-server 198.51.100.2 version9 template v4;

  • set forwarding-options sampling instance s1 family inet output interface sp-2/1/0 source-address 192.168.1.2

  • set routing-options static route 203.0.113.0/8 next-hop 192.0.2.2

  • set services flow-monitoring version9 template v4 flow-active-timeout 30

  • set services flow-monitoring version9 template v4 flow-inactive-timeout 30

  • set services flow-monitoring version9 template v4 ipv4-template

Verifying Your Work

To verify that your configuration is working as expected, use the following commands on the router that is configured with the sampling instance:

  • show services accounting aggregation template template-name template-name

  • show services accounting flow

The following shows the output of the show commands issued on the MX480 router used in this configuration example: