[j-nsp] loop detection on EX4200

[Victor Sudakov]

Ben Dale wrote:
> 
> 
> >> 
> >>> No, LLDP does not work either across the multiplexer. If I configure a
> >>> vlan tag on the "default" vlan on the EX42, LLDP starts seeing the
> >>> EX42 on the other side.
> >>> 
> >>> That was the reason I had suggested that the multiplexer did not
> >>> forward untagged frames.
> >> 
> >> That is certainly odd.  Even on a trunked interface with no native-vlan configured at all, LLDP PDUs should still be sent untagged:
> >> 
> >> bdale at elow-core-01# show interfaces ge-1/1/5                               
> >> vlan-tagging;
> >> unit 3830 {
> >>    vlan-id 3830;
> >>    family inet {
> >>        address 10.237.18.29/31;
> >>    }
> >>    family mpls;
> >> }
> > 
> > This is probably because your interface is in the "vlan-tagging" mode,
> > while mine is "family ethernet-switching" mode.
> 
> I see the same behaviour on a 4200.  LLDP is always sent untagged:

That's what I see arriving:

11:36:38.318202  In 3c:8a:b0:da:67:59 > 01:80:c2:00:00:0e, ethertype 802.1Q (0x8100), length 74: vlan 1, p 5, ethertype LLDP, LLDP, name sw-km337, length 56
        [|LLDP]

If I "delete vlans default vlan-id" on the switch, I'll stop seeing these
frames. BTW on the remote sw-km337 switch, the default vlan is untagged.

-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
sip:sudakov at sibptus.tomsk.ru