Policy Framework Configuration Guide - Juniper Networks

Chapter 15: Traffic Forwarding and Monitoring Configuration
• On all routers except the MX Series router, you can configure only one port-mirroring
interface per router. If you include more than one interface in the port-mirroring
statement, the previous one is overwritten. MX Series routers support more than one
port-mirroring interface per router.
• You can configure multiple port-mirroring instances on the M120, M320, and MX Series
routers.
• You can specify both host (cflowd) sampling and port mirroring in the same
configuration. You can perform RE-sampling and port mirroring actions simultaneously.
However, you cannot perform PIC-sampling and port mirroring actions simultaneously.
• In typical applications, you send the sampled packets to an analyzer or a workstation
for analysis, not to another router. If you must send this traffic over a network, you
should use tunnels. For more information about tunnel interfaces, see the Junos OS
Network Interfaces Configuration Guide.
Configuring Port Mirroring
To configure port mirroring, include the port-mirroring statement at the [edit
forwarding-options] hierarchy level:
[edit forwarding-options]
port-mirroring {
family (ccc | inet | inet6 | vpls) {
output {
interface interface-name {
next-hop address;
}
no-filter-check;
}
input {
maximum-packet-length bytes;
rate number;
run-length number;
}
}
}
Configuring the Port-Mirroring Address Family and Interface
To configure port mirroring, include the port-mirroring statement. To configure the address
family type of traffic to sample, include the family statement. To configure the rate of
sampling, length of sampling, and the maximum size for the mirrored packet, include the
input statement. To specify on which interface to send duplicate packets and the next-hop
address to send packets, include the output statement. To determine whether there are
any filters on the specified interface, include the no-filter-check statement.
For information about the rate and run-length statements, see “Configuring Traffic
Sampling” on page 347.
Configuring Multiple Port-Mirroring Instances
In Junos OS Release 9.5 and later, you can configure multiple port-mirroring instances
on the M120, M320, and MX Series routers. On the M120 router, you can associate each
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