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No MAC Address...

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  • 1.  No MAC Address...

    Posted 11-20-2019 00:44

    Hello,

    VC with 7 switch EX4300-48P - Junos 18.2R3.4.
    Several ports on different members do not learn MAC adresse of connected hosts.
    Physical link is Up, Negotiation status: Complete, No errors,... all seems OK but no network on this ports.
    Mac address table is empty for somme ports. Delete interface, re-create interface, disable/enable, disable/enable poe...


    Nothing can be done about it!
    What would you suggest to correct this problem?
    Thanks

     

     

     



  • 2.  RE: No MAC Address...

     
    Posted 11-20-2019 02:51
    Hi Louis,

    What is the configuration on these ports? Do end hosts connected to these ports have valid IPs and generate traffic? Remember the switch needs some traffic from the far end to learn MAC address (based on source MAC of the packets).

    If you have a properly family (ethernet-switching for L2) configured, you can start with "show interfaces extensive <>" and see the stats if there are any incoming packets. If that doesn't give a clue, perform a port-mirror on one of the ports to see if the switch does receive frames from the hosts which it can use to learn MACs.
    Sample port-mirror config: https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/port-mirroring-cli-els.html

    Hope this helps.

    Regards,
    -r.

    --------------------------------------------------

    If this solves your problem, please mark this post as "Accepted Solution."
    Kudos are always appreciated :).


  • 3.  RE: No MAC Address...

    Posted 11-20-2019 03:35

    Port configuration is very very basic :

    description ****PORT_HS****;
    ether-options {
        auto-negotiation;
    }
    unit 0 {
        family ethernet-switching {
            interface-mode access;
            vlan {
                members vlan4032;
            }
        }
    }

    For now, end host has no ip address because it is configured in dhcp. Because production, hosts have been connected on others ports. Users have to work ! I have 3 ports on this vc (but on two differents members) in the same bad state.
    I will connect an other station an try to analyse traffic with mirroring.



  • 4.  RE: No MAC Address...

     
    Posted 11-20-2019 04:14
    Hi Louis,

    Where is the DHCP server at, is it in the same VLAN or relayed? Are all these ports part of the same VLAN? Please configure static IP on the hosts and see if they can communicate fine.

    Yes port mirror should help confirm if the switch receives the Discovers or not. Please also check the “switch-options” in the configuration is all default and no group config sitting somewhere disabling MAC learning 😊.

    Hope this helps.

    Regards,
    -r.

    --------------------------------------------------

    If this solves your problem, please mark this post as "Accepted Solution."
    Kudos are always appreciated :).


  • 5.  RE: No MAC Address...
    Best Answer

     
    Posted 11-20-2019 06:46

    You should also check that these ports are not shut down by spanning-tree or bpdu-guard.

     

    show ethernet-switching interface ge-x/x/x
    show spanning-tree interface ge-x/x/x


  • 6.  RE: No MAC Address...

     
    Posted 11-20-2019 07:11

    Quick question - if you move the connection from a 'bad' port to a 'good' port, does the situation follow the device, or remain with the same port?  This should tell you if situation is related to EX4300 or to the external devices.  If remains with port, then suggest you look and compare configuration of these ports, and also check that nothing extra inherited from Groups, if indeed you are using groups at all.

     

    You also mentioned POE.  So what is the attached device, AP or IoT device or what?   Could it be expected that with no IP address, it sends no Ethernet frames?

     

    Good luck.  If this behavior continues, I suggest opening a TAC case, if you have not already done so.



  • 7.  RE: No MAC Address...

    Posted 11-25-2019 01:42

    Sorry for the delay but we had a big electrical problem on one of our datacenter.

    I have explored all the ideas mentioned here, and the winner is... strorm-control !!!

     

    The "SCTL" flags were up on these interfaces. Once found, the search in logs confirms the problem :

     

    Nov 20 16:09:56  sw.edge.2 l2ald[1774]: L2ALD_ST_CTL_ENABLED: ge-3/0/25.0: storm control enabled port
    Nov 20 16:09:56  sw.edge.2 l2ald[1774]: L2ALD_ST_CTL_ENABLED: ge-3/0/43.0: storm control enabled port
    Nov 20 16:09:56  sw.edge.2 l2ald[1774]: L2ALD_ST_CTL_ENABLED: ge-4/0/7.0: storm control enabled port
    Nov 20 16:51:02  sw.edge.2 l2ald[1774]: L2ALD_ST_CTL_IN_EFFECT: ge-2/0/36.0: storm control in effect on the port
    Nov 20 16:51:02  sw.edge.2 l2ald[1774]: L2ALD_ST_CTL_DISABLED: ge-2/0/36.0: storm control disabled port
    

    A VERY BIG THANK YOU TO ALL OF YOU