Ttyjfyk

Suppose I have a subinterface with Vlan-vpls encapsulation, like this one:

admin@router> show configuration interfaces ge-2/1/1
flexible-vlan-tagging;
encapsulation flexible-ethernet-services;
unit 17 
 encapsulation vlan-vpls;
 vlan-id 17;

Is there any command in Junos which would show me a VPLS instance associated with this subinterface (ge-2/1/1.17)?

If there are MACs in mac-table then I can use

show vpls mac-table interface ge-2/1/1.17

but what if there are no MACs?

There is no direct way, but you can see interfaces in the statistics:

user@router> show vpls statistics

[..]
Instance: EXAMPLE-VPLS-INSTANCE
 Local interface: ae2.2000, Index: 380
[..]

Or in the extensive flood list:

user@router> show vpls flood extensive
[..]
Name: EXAMPLE-VPLS-INSTANCE
[..]
 Flooding to:
 Name Type NhType Index
 __all_ces__ Group comp 1246 
 Composition: split-horizon
 Flooding to:
 Name Type NhType Index
 ae2.2000 CE ucst 1057 

or in the extensive connections:

user@router> show vpls connections extensive
[..]
Instance: EXAMPLE-VPLS-INSTANCE
Edge protection: Not-Primary
 Local site: local-sites (1)
 Number of local interfaces: 1
 Number of local interfaces up: 1 
 IRB interface present: no
 ae2.2000 

Try this command show vpls connections instance <instance-name> extensive to view the interfaces associated with the VPLS instance .

Additional Info >> To check the MAC table , use the command show vpls mac-table instance <instance-name> , it will show you all the MAC addresses learnt in that VPLS instance. If you are using 'vlan-id all' knob in the VPLS instance configuration , then this command will show you MAC Table VLAN based.

To check the MAC table VLAN specific , use the command show vpls mac-table instance <instance-name> vlan-id <vlan-id>.

If you want to see the MAC table specific to some interface , you can use the command show vpls mac-table instance <instance-name> | match <interface-name>'

MAC learning in VPLS is only data plane based. So in case there are no MACs means no packets are forwarded to / from the CE. When CE broadcast /multicast/unicasts the packets the PE learns the MAC address just like normal LAN switch.