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  • 1.  remote span on qfx 55170/5200

    Posted 09-05-2022 11:48
    Hi guys,

    I went through all the documentation but it doesn't cover what I really need. My topology is the following:

    server1--- switch ---- many routers--- switch---server2

    I want to mirror all the traffic from server1 and to send the packets to server2. Would it be possible? And if yes how?



    Michele Toblini

  • 2.  RE: remote span on qfx 55170/5200

    Posted 10-12-2022 18:15
    Hi Michele,  

    Analyzer/ port-mirroring Encapsulated Remote Switched Port Analyzer (ERSPAN) is a very useful addition to the analyzer family of SPAN & RSPAN where it facilitates the transport of mirrored traffic over an IP network. The traffic is encapsulated in a GRE-Header at the source router and is transferred across the network.

    set forwarding-options​ analyzer a1 input #input-interface
    set forwarding-options​ analyzer a1 output ip-address 
                    #run show forwarding-options analyzer a1
    set forwarding-options​ port-mirroring instance pm1  family inet output ip-address  

    Note : Destination IP should be a valid unicast IP , Non local and reachable IP.

    (for example: it should not be loop back address, router ip address etc)

    • IPv6 is not supported as an ERSPAN delivery method.
    • There is a 64 byte hard limit for egress encapsulation for tunneled packets. 
    • If more than 1 IP's are reachable through same physical interface then only one of them can be used as ERSPAN destination IP for analyzer sessions.

    For more details on port-mirroring on QFX


    For more details on analyzer/port-mirroring on EX4300:


    Esteban M

  • 3.  RE: remote span on qfx 55170/5200

    Posted 10-12-2022 18:57

    [Junos] GRE Configuration Example