AOS-CX Switch Simulator

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DNS traffic mirroring

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  • 1.  DNS traffic mirroring

    Posted Jan 10, 2022 01:16 PM
    Hi Teams
    is that possible to configure Traffic/Port Mirroring with filter possibility? for example Mirroring only for DNS and other protocols/traffics ignore. Thank you

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    Filmon Eyob
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  • 2.  RE: DNS traffic mirroring

    EMPLOYEE
    Posted Jan 10, 2022 01:30 PM
    Hi Filmon,

    According latest Release Notes https://www.arubanetworks.com/techdocs/AOS-CX/10.09/RN/rn_ova_10-09-0002.pdf Mirroring feature and Classifier Policy feature are configurable, but are non-functional (page 5). Otherwise if you are interested in such feature per se or would like to try it on a real gear, here is an example how to do it - https://www.arubanetworks.com/techdocs/AOS-CX/10.09/PDF/monitoring_8400.pdf , page 60, "Classifier policies and mirroring sessions".

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    Ivan Bondar
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  • 3.  RE: DNS traffic mirroring

    Posted Jan 11, 2022 02:05 AM
    Hello Ivan
    thank you very much for your answer.
    I did some tests but that could not help me to solve my problem. In Wirshark it mirrors everything . it is not filtered only for DNS as configured in Classifier.
    Here is my configuration:
    6300# config
    6300(config)# mirror session 1

    6300(config-mirror-1)# destination cpu
    6300(config-mirror-1)# enable

    class ip DNS
    match udp any any eq 53
    ignor any any any

    policy DNS_Mirroring
    class ip DNS action mirror 1

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    Filmon Eyob
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  • 4.  RE: DNS traffic mirroring

    EMPLOYEE
    Posted Jan 11, 2022 02:30 AM
    Have you tried to use as the destination a physical port on the switch, not CPU? The reason I am asking is that CPU can be hit with all kinds of traffic that needs its attention coming on all ports, like link-local packets like LLDP, routing protocols packets like OSPF Hello etc etc. It's been a while since I used this type of mirroring on AOS-CX and I don't remember if it has this specific, but it can be the case. Therefore in order to be sure you see only the traffic that is mirrored try to use physical interface as destination of the mirroring session. Also, I'd get rid of 'ignore any any any' in the policy and keep only the 'match' clause.

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    Ivan Bondar
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