The topology diagram below shows multiple CPE devices, each has multiple WAN sub-interface that are dot1q tagged as VLAN 10 and 20 in this example. The PE ME3600 devices has an SVI with an IP address in a /24 range in VLAN 20 and each CPE has a WAN interface encapsualted in VLAN 20 within the same /24. This topology is all configured an working just fine. A CPE can ping .1 and the PE can ping .10 for example.
The layer 2 aggregation device adds a QinQ outer tag to each CPE connection so that at the PE device each layer 2 connection can be differenciated between despite trunking the same VLANs to each CPE with their IPs being in a /24.
The config the ME3600 port is as follows;
interface GigabitEthernet0/1 switchport trunk allowed vlan none switchport mode trunk service instance 11 ethernet description cust1-LAN encapsulation dot1q 101 second-dot1q 10 rewrite ingress tag pop 2 symmetric bridge-domain 10 ! service instance 101 ethernet description cust1-MGMT encapsulation dot1q 101 second-dot1q 20 rewrite ingress tag pop 2 symmetric bridge-domain 20 ! service instance 12 ethernet description cust2-LAN encapsulation dot1q 102 second-dot1q 10 rewrite ingress tag pop 2 symmetric bridge-domain 10 ! service instance 102 ethernet description cust21-MGMT encapsulation dot1q 102 second-dot1q 20 rewrite ingress tag pop 2 symmetric bridge-domain 20 ! interface Vlan20 ip address 10.10.10.1 255.255.255.0
What I want to know is;
How can I see the outer tag the ME3600 will apply to frames sent out towards one of the CPEs, lets say 10.10.10.10? Something like
show ip cef exact-route or
show ip arp that shows the path the traffic will take through the EFPs and EVC back towards the CPE?
The test scenario is that I want to see what outer tag will be applied by the PE device when sending taffic to 10.10.10.15, the 2nd CPE (which allows me to verify that 10.10.10.15 came in on VLAN 102 and was correctly encapsulated from the downstream layer 2 aggregation device which is not Cisco and out of the scope of this question - I'm looking solely at the ME3600)
If I look at the ARP entry for the CPE 10.10.10.10 for example I get output like the following;
show ip arp 10.10.10.10 Protocol Address Age (min) Hardware Addr Type Interface Internet 10.10.10.10 4 0001.1111.1111 ARPA Vlan20
With the QinQ scenario above the sevice instance under gi0/1 strips off outer VLAN 100 and inner VLAN 20 then bridges to SVI 20. The 3600 must have recorded the way that traffic came in through the EVC to send it back, where can I see that?