The use of an Adaptive Services Physical Interface Card (PIC) or a Monitoring Services Physical Interface Card
(PIC) allows network operators to perform sampling of network traffic, reducing the load placed on the routing-engine. This article provides a sample configuration and highlight some common mistakes made when using this service.

The following configuration can be used to configuring sampling which will be processed by the routing-engine.

forwarding-options {
    sampling {
        input {
            family inet {
                rate <rate> ;
                run-length <run-rate> ;
            }
        }
        output {
            cflowd <host_ip> {
                version 8;
            }
        }
    }

This sampling configuration is activated by applying a firewall filter with the action 'sample' to interfaces which are interesting. When attempting to sample large amounts of data, the routing-engine may discard traffic which was destined to be sampled. The use of a Service PIC to provide this functionality will increase the volume of traffic that can be sampled.

An Monitoring Services PIC, Adaptive Services PIC or internal Adaptive Services Module (M7i) can be used to produce cflowd accounting, bypassing the need for the routing-engine to process sampled packets. This will reduce the volume of packets which are forwarded to the routing-engine for processing.

The following is an example configuration for configuration of an Adaptive Services PIC:

forwarding-options {
    sampling {
        input {
            family inet {
                rate <rate> ;
                run-length <run-rate> ;
            }
        }
        output {
            cflowd <host_ip> {
                version 8;
            }
            interface sp-1/2/0 {
                source-address <cflowd_source_ip_address> ;
            }     
        }
    }
}

As with the previous routing-engine processed sampling example, a firewall filter on the transit interface matches interesting packets and sets the terminating action 'sample':

firewall {
    family inet {
        filter sampling-filter {
            term default {
                then {
                    sample;
                    accept;
                }  
            }
        }
    }
}

Note: In order to use the Service PIC to generate accounting cflowd packets, you will need to enable the family inet on the interface:

interfaces {
    sp-1/2/0 {
        unit 0 {
            family inet;
        }
    }
}

The status of the sampling can be verified with the command show services accouting status , as shown in the following example:

lab@m7i# run show services accounting status 

Service Accounting interface: sp-1/2/0, Local interface index: 131

Service name: (default sampling)

Interface state: Accounting

Service ID: 0

Export interval (in seconds): 60, Export format: cflowd v8

Protocol: IPv4, Engine type: 188, Engine ID: 34

Route record count: 10, IFL to SNMP index count: 15, AS count: 2

Time set: Yes, Configuration set: Yes

Route record set: Yes, IFL SNMP map set: Yes