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Enabling Passive Monitoring on Ethernet Interfaces

When you configure an interface in passive monitoring mode, the Packet Forwarding Engine silently drops packets coming from that interface and destined to the router itself. Passive monitoring mode also stops the Routing Engine from transmitting any packet from that interface. Packets received from the monitored interface can be forwarded to monitoring interfaces. If you include the passive-monitor-mode statement in the configuration:

  • Gigabit and Fast Ethernet interfaces can support both per-port passive monitoring and per-VLAN passive monitoring. The destination MAC filter on the receive port of the Ethernet interfaces is disabled.

  • Ethernet encapsulation options are not allowed.

  • Ethernet interfaces do not support the stacked-vlan-tagging statement for both IPv4 and IPv6 packets in passive monitor mode.

To enable packet flow monitoring on Ethernet interfaces:

  1. In configuration mode, go to the [edit interfaces interface-name] hierarchy level.
  2. Include the passive-monitor-mode statement.

For IPv4 monitoring services interfaces, enable packet flow monitoring by including the family statement at the [edit interfaces mo-fpc/pic/port unit logical-unit-number] hierarchy level, specifying the inet option:

  1. In configuration mode, go to the [edit interfaces mo-fpc/pic/port unit logical-unit-number] hierarchy level.

  2. Include the passive-monitor-mode statement.

For conformity with the cflowd record structure, you must include the receive-options-packets and receive-ttl-exceeded statements at the [edit interfaces mo-fpc/pic/port unit logical-unit-number family inet] hierarchy level:

  1. In configuration mode, go to the [edit interfaces mo-fpc/pic/port unit logical-unit-number family inet] hierarchy level.

  2. Include the receive-options-packets and receive-ttl-exceeded statements.

IPv6 passive monitoring is not supported on monitoring services PICs. A user must configure port mirroring to forward the packets from the passive monitored ports to other interfaces.

For information on FPCs and PICs that support IPv6 passive monitoring on the T640, T1600, and T4000 routers, see Passive Monitoring on Ethernet Interfaces Overview. Interfaces configured on these FPCs and PICs support IPv6 passive monitoring.

To configure port mirroring, include the port-mirroring statement at the [edit forwarding-options] hierarchy level.

For the monitoring services interface, you can configure multiservice physical interface properties. For more information, see Configuring Multiservice Physical Interface Properties and the Junos OS Services Interfaces Library for Routing Devices.

Related Documentation