[j-nsp] Port Mirroring on M7i

Mario DEL RE mario.delre at gmail.com
Fri Mar 6 16:24:33 EST 2009

Hello all,

I would like to do Port Mirroring on an interface. I can mirror the IN
traffic of my interface, but I can not mirror the OUT traffic.

 The global topology is as follows:
*J4300 *------------------ (mirrored port,1/3/0.100)
*M7i*(1/3/1.0)----------------> Mirrored Traffic's destination.

Here is the mirrored port:

lab at m7# show interfaces fe-1/3/0


unit 100 {

    vlan-id 100;

    family inet {

        filter {

            input mirror_in;

            output mirror_out;





And the filters are as follows:

lab at m7# show firewall family inet filter mirror_in

term 1 {

    then {





The mirror_out filter is exactly the same as mirror_in. My Forwarding
options are as follows:

lab at m7# show forwarding-options

port-mirroring {

    family inet {

        input {

            rate 1;

            run-length 1;


        output {

            interface fe-1/3/1.0 {






When I generate a traffic between the J4300 and the M7i (a ping from J4300
to M7i for example), the M7i only mirrors the INPUT packets to the interface
fe-1/3/1.0. I am sure that it's the input traffic (and not the output
traffic) by deactivating the filters one by one. The output traffic is not
mirrored at any time.

Should I add/change some config to also mirror the output traffic, or is it
a default Junos behaviour? (Junos: 8.3R2.11)

Thanks in advance,

Mario DEL RE

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