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Forum Discussion

Richard-Chapman's avatar
Apr 01, 2019

MLD not working as expected with local link addresses and local list multicast

This might well be a miss understanding of how IPv6 works but I've asked around and other confurmed my thinking. This is in a pure IPv6 setup, I am not using IPv4 (other than the web admin).


1) I have 3 hosts, each using there local link IPv6 address.

2) Host A is sending packets to a local link scoped multicast group "ff02::3000"

3) Host B is sending packets to a local link scoped mulitcast group "ff02::3010"

4) Host C is running wireshark and can see all the packets from Host A and B. Host C has not subscribed to ither of the multicast groups.


I have followed https://kb.netgear.com/21999/How-do-I-configure-Multicast-Listener-Discovery-MLD-snooping-using-the-web-interface-on-my-managed-switch as told too by chat and spend a number of hours playing around with other settings.

I can get C not to see any traffic if I disable MLD snooping (sometimes, it appears that the config might not apply)


I'm at a bit of a loss.  Anyone got an idea or is this a bug

 

Thanks

9 Replies

  • Retired_Member's avatar
    Retired_Member

    Hi Richard-Chapman ,                                                                                                                         

    Welcome to the community! 

                                          

    For further analysis,Could you please provide the tech-support file of the Switch:
    How do I send tech-support files from my Managed Switch to NETGEAR community moderators?
    https://kb.netgear.com/31439/How-do-I-send-diagnostic-files-from-my-Managed-Switch-to-NETGEAR-community-moderators

     

    BTW:

    Could you run below command in your switch console/telnet session?

    1.show mldsnooping

    2.show mldsnooping ssm groups


    Regards,

    EricZ
    NETGEAR employee

    • Richard-Chapman's avatar
      Richard-Chapman
      Aspirant

      Hi EricZ,

      Sorry for the delay.  I've sent the files to switch_support after I factory reset the switch and applied the steps set out in my original post. Still seeing all traffic to C and C never joins the groups.

       

      Output you requested

      (M4300-8X8F) #show mldsnooping

      Admin Mode..................................... Enable
      Multicast Control Frame Count.................. 0
      Interfaces Enabled for MLD Snooping............ None
      VLANs enabled for MLD snooping................. 300

      (M4300-8X8F) #show mldsnooping ssm groups

      VLAN Source
      ID Group Interface Reporter Filter Mode Source Address List
      ---- ---------------- --------- ---------------- ----------- -------------------
      There are currently no entries in the table.

      (M4300-8X8F) #

       

      I've got a the big brother of this switch on my desk as well so will be testing that shortly.

       

      Thanks

      • Retired_Member's avatar
        Retired_Member

        Hi Richard-Chapman 

         

        I got your tech-support file, thanks!

         

        I notice there is 4 up ports(1,2,7,10), so how abount connection to Host A/B/C.

        And you running MLD Snooping on VLAN300, right? And only port(1,2,7) belong VLAN300. So which host is running MLD Server role? and Which host is running MLD Client role?

        As in MLD Snooping feature, first the Client will send report packet to join Multicast Group, then the Server will send Multicast stream to different Groups, only the Client has joined the correct Group can receive the Multicast.

        Due to there is no any Groups info when you run command 'show mldsnooping ssm groups', so please double chek if the Clients send out report packet to join Groups?

         

        Then on all ports, there is no need to enable 'ipv6 pim'.

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