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  • 1.  LLDP issues between MX960 and EX4200

    Posted 11-29-2022 08:09
    Edited by AlexMolon 11-29-2022 08:10
    Hi All,
    I'm facing a problem regarding LLDP between a MX960 and a EX4200.
    Basically the EX4200 is receiving and transmitting LLDP informations properly, and i can see the MX960 in the EX4200 LLDP neigbour table.
    But for some reason the MX960 is only sending but not receiving anything from the EX4200.

    Bear in mind that the EX4200 is also connected to another device by another vendor and everything is fine on that side.
    In the EX i'm using this interface configuration:
    # show interfaces xe-0/1/0
    description "to MX960 xe-7/2/2";
    vlan-tagging;
    mtu 9192;
    unit 3600 {
        vlan-id 3600;
        family inet {
            address 192.168.0.2/30;
        }
    }
    ​

    In the MX960 i've try both following configurations, both  are showing the same issue

    # show interfaces xe-7/2/2
    description "to EX4200 xe-0/1/0";
    flexible-vlan-tagging;
    mtu 9192;
    encapsulation flexible-ethernet-services;
    unit 3600 {
        vlan-id 3600;
        family inet {
            address 192.168.0.1/30;
        }
    }
    ​

    or

    # show interfaces xe-7/2/2
    description "to EX4200 xe-0/1/0";
    vlan-tagging
    mtu 9192;
    unit 3600 {
        vlan-id 3600;
        family inet {
            address 192.168.0.1/30;
        }
    }
    ​

    Obviously LLDP is active in all the interfaces.

    As you can see below, the EX receives and transmit, while the MX is transmitting but not receiving

    in the EX4200
    # run show lldp statistics
    Interface    Parent Interface  Received  Unknown TLVs  With Errors  Discarded TLVs  Transmitted  Untransmitted
    xe-0/1/0.0   -                 258       0             0            0               254          0
    ​



    in the MX960
    > show lldp statistics
    Interface    Parent Interface  Received  Unknown TLVs  With Errors  Discarded TLVs  Transmitted  Untransmitted
    xe-7/2/2     -                 0         0             0            0               79           0
    ​

    I think in someway this is related to the fact that the EX4200 sends out the LLDP messages from xe-0/1/0.0, while the MX960 is using the xe-7/2/2.32767 (even if they should be tagged in the same way: VLAN-Tag [ 0x0000.0 ]) 

    Anyone can help please?

    ------------------------------
    Alex Molon
    ------------------------------


  • 2.  RE: LLDP issues between MX960 and EX4200

    Posted 11-30-2022 04:12
    LLDP shouldn't care about VLAN tags. It may be that the EX thinks it's sending LLDP frames but really doesn't. Try "monitor traffic no-resolve size 1500 interface xe-0/1/0 matching "ether[12:2]=0x88cc" " on the EX (and MX with xe-7/2/2). The matching string filters out LLDP specifically so you don't have to see DHCP and other broadcasts.

    Edit: You live ans learn, 0-tagged LLDP frames was news to me as well!


  • 3.  RE: LLDP issues between MX960 and EX4200

    Posted 11-30-2022 04:41
    This is what i see in the EX4200

    Listening on xe-0/1/0, capture size 1500 bytes
    
    23:27:27.625930  In LLDP, name mx960, length 264
    23:27:56.646835  In LLDP, name mx960, length 264
    23:28:24.333358  In LLDP, name mx960, length 264
    23:28:53.767945  In LLDP, name mx960, length 264
    23:29:20.138226  In LLDP, name mx960, length 264
    23:29:46.171597  In LLDP, name mx960, length 264
    ​

    while this is what i see in the MX960

    Listening on xe-7/2/2, capture size 1500 bytes
    
    09:32:22.330548 Out LLDP, name mx960, length 264
    09:32:48.364129 Out LLDP, name mx960, length 264
    09:33:16.920616 Out LLDP, name mx960, length 264
    09:33:45.660613 Out LLDP, name mx960, length 264
    ​

    All seems to point to the fact that the EX4200 is not sending LLDP frames..... But why?

    in protocol lldp there is the statement "interfaces all", i've also specifically added the interface xe-0/1/0 to be sure...

    # show protocols lldp
    interface all;
    interface xe-0/1/0.0;
    ​


    And what is puzzling me is that the same switch is connected also to Cisco Nexus and everything on that side is working well.

    It seems that LLDP is not working due to the interface configuration, but i cannot figure out the reason.



    ------------------------------
    Alex Molon
    ------------------------------



  • 4.  RE: LLDP issues between MX960 and EX4200

    Posted 11-30-2022 05:04
    Update on my previous message....
    i've changed the monitor command to:
    monitor traffic interface xe-0/1/0 layer2-headers no-resolve size 1500 matching "ether dst 01:80:c2:00:00:0e"

    and now i see.....

    Listening on xe-0/1/0, capture size 1500 bytes
    
    23:54:48.099371  In 2c:6b:f5:d6:14:d7 > 01:80:c2:00:00:0e, ethertype LLDP (0x88cc), length 278: LLDP, name mx960, length 264
    23:54:49.049452 Out 00:26:88:61:37:33 > 01:80:c2:00:00:0e, ethertype 802.1Q (0x8100), length 332: vlan 0, p 6, ethertype LLDP, LLDP, name ex4200, length 314
    23:55:15.515439 Out 00:26:88:61:37:33 > 01:80:c2:00:00:0e, ethertype 802.1Q (0x8100), length 332: vlan 0, p 6, ethertype LLDP, LLDP, name ex4200, length 314
    23:55:17.366614  In 2c:6b:f5:d6:14:d7 > 01:80:c2:00:00:0e, ethertype LLDP (0x88cc), length 278: LLDP, name mx960, length 264
    ​

    It seems that the MX sends LLDP frames untagged, but the EX4200 is sending them tagged as VLAN0. And maybe that's the reason why the MX is not detecting them.

    Any idea on how to fix this?
    Or how to set VLAN0 as untagged on the EX4200 port?

    I've tried with "set interface xe-0/1/0  native-vlan-id 0" (like i can do in the MX960) but the option doesn't exist in the EX4200

    ------------------------------
    Alex Molon
    ------------------------------



  • 5.  RE: LLDP issues between MX960 and EX4200
    Best Answer

    Posted 11-30-2022 05:22

    https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/no-tagging-lldp-ex-series.html ?

    Syntax
    no-tagging;
    
    Hierarchy Level
    
    [edit protocols lldp]
    
    Release Information
    Statement introduced in Junos OS Release 14.1X53-D10 for EX Series switches.
    
    Description
    Configure the switch to send LLDPDUs without including VLAN tags on interfaces for which VLAN tagging in enabled (tagged interfaces).
    
    Default
    Interfaces for which VLAN tagging is enabled include a VLAN tag (tag 0) in LLDPDUs if the no-tagging option is not configured.


    This I did not know...




  • 6.  RE: LLDP issues between MX960 and EX4200

    Posted 11-30-2022 05:28
    EusaHues this is exactly what i needed.
    Thanks a lot! You've saved my day

    ------------------------------
    Alex Molon
    ------------------------------