[j-nsp] EX4200 LLDP issue with vlan-tagging

[Jeff Wheeler]

I find that EX4200 with interfaces configured with vlan-tagging and
layer-3 sub-interfaces, as opposed to family ethernet-switching and
routed VLAN interfaces, transmit LLDP frames differently.  I do not
think this is the correct behavior, but I would appreciate comments.

The interfaces configured as follows:
interface xe-1/1/1 {
  vlan-tagging;
  unit 3911 {
    vlan-id 3911;
    family inet {
      address 192.0.2.1/24;
    }
  }
}
produces LLDP frames that appear like this:
08:39:23.892264 Out 00:19:e2:51:86:99 > 01:80:c2:00:00:0e, ethertype
802.1Q (0x8100), length 68: vlan 0, p 0, ethertype LLDP, LLDP,0

Notice the outer-ethertype 0x8100 rather than 0x88CC.  Surely this is
not correct.

Changing the configuration to something like:
interface xe-1/1/1 {
  unit 0 {
    family ethernet-switching {
      port-mode trunk;
      vlan {
        members 3911;
      }
    }
  }
}
interface vlan.3911 {
  family inet {
    address 192.0.2.1/24;
  }
}
vlan v3911 {
  vlan-id 3911;
  l3-interface vlan.3911;
}
produces LLDP frames which appear normal:
08:50:01.121422 Out 00:19:e2:51:86:bf > 01:80:c2:00:00:0e, ethertype
LLDP (0x88cc), length 74: LLDP, name J3K3.1250RL, length 60

In the first case, my neighboring devices are dropping the LLDP
frames, and thus they do not learn about the advertising device.  In
the later case, everything works as expected.  With both
configurations, the EX4200 itself does detect the neighboring
LLDP-speakers correctly.

-- 
Jeff S Wheeler <jsw at inconcepts.biz>
Sr Network Operator  /  Innovative Network Concepts