This article provides insights into how incorrect configurations on a spoke router within a H-VPLS (Virtual Private LAN Service) setup can result in the L2Circuit remaining in a "No Ongoing Label (OL)" state. Specifically, it addresses issues related to neighbor misconfigurations in the routing-instance and explains how to resolve them.

Topology

SPOKE ACX7024-A ------ HUB1 ACX7024-B ----- HUB2 ACX7024-C

L2Circuit remains in the "OL (No Ongoing Label)" state, preventing the circuit from becoming operational.

Output from the show l2circuit connections command indicates no ongoing label and lists the connection status as "OL".

The spoke router has incorrectly configured itself as its own neighbor within the VPLS routing-instance.

Adding the correct neighbor configuration still results in an encapsulation mismatch, preventing the circuit from establishing connectivity.

Configuration for H-VPLS on Spoke router:

set routing-instances HUB2 instance-type virtual-switch

set routing-instances HUB2 protocols vpls mesh-group HUB2 neighbor <Is a Mistake to include the same local lo0 IP address here>

set routing-instances HUB2 protocols vpls mesh-group HUB2 vpls-id 123

set routing-instances HUB2 protocols vpls no-control-word

set routing-instances HUB2 protocols vpls no-tunnel-services

set routing-instances HUB2 protocols vpls ignore-mtu-mismatch

set routing-instances HUB2 interface et-0/0/6.750

set routing-instances HUB2 vlans HUB2 vlan-id 760

set routing-instances HUB2 vlans HUB2 interface et-0/0/6.750

>show interfaces et-0/0/6.750 | display set

set interfaces et-0/0/6 unit 750 encapsulation vlan-vpls

set interfaces et-0/0/6 unit 750 vlan-id 760

set interfaces et-0/0/6 unit 750 family ethernet-switching

labroot@ACX7024-A (SPOKE)# run show vpls connections 

Layer-2 VPN connections:

Legend for connection status (St)  

EI -- encapsulation invalid   NC -- interface encapsulation not CCC/TCC/VPLS

EM -- encapsulation mismatch   WE -- interface and instance encaps not same

VC-Dn -- Virtual circuit down  NP -- interface hardware not present 

CM -- control-word mismatch   -> -- only outbound connection is up

CN -- circuit not provisioned  <- -- only inbound connection is up

OR -- out of range        Up -- operational

OL -- no outgoing label     Dn -- down            

LD -- local site signaled down  CF -- call admission control failure    

RD -- remote site signaled down SC -- local and remote site ID collision

LN -- local site not designated LM -- local site ID not minimum designated

RN -- remote site not designated RM -- remote site ID not minimum designated

XX -- unknown connection status IL -- no incoming label

MM -- MTU mismatch        MI -- Mesh-Group ID not available

BK -- Backup connection     ST -- Standby connection

PF -- Profile parse failure   PB -- Profile busy

RS -- remote site standby    SN -- Static Neighbor

LB -- Local site not best-site  RB -- Remote site not best-site

VM -- VLAN ID mismatch      HS -- Hot-standby Connection

Legend for interface status 

Up -- operational      

Dn -- down

Instance: HUB2

 Mesh-group connections: HUB2

  Neighbor         Type St   Time last up     # Up trans

  SPOKE lo0 IP (vpls-id 123) rmt OL  

Configuration on the ACX7024-C or HUB2

set protocols l2circuit neighbor SPOKE lo0 IP interface ae0.760 virtual-circuit-id 123

set protocols l2circuit neighbor SPOKE lo0 IP interface ae0.760 no-control-word

set protocols l2circuit neighbor SPOKE lo0 IP interface ae0.760 encapsulation-type ethernet-vlan

set protocols l2circuit neighbor SPOKE lo0 IP interface ae0.760 ignore-encapsulation-mismatch

set protocols l2circuit neighbor SPOKE lo0 IP interface ae0.760 ignore-mtu-mismatch

set protocols l2circuit neighbor SPOKE lo0 IP interface ae0.760 pseudowire-status-tlv

root@ACX7024-C(HUB2)# run show l2circuit connections
<SNIPPED>

Neighbor: SPOKE lo0 IP

    Interface                Type St    Time last up         # Up trans

   ae0.760(vc 123)          rmt  OL   

 

 

 

As you can see, when we add the IFL ae0.760 to the protocols l2CKT the CCC IFL gets reported as DOWN.

 

root@ACX7024-C(HUB2)# run show interfaces terse ae0.760 

Interface              Admin Link Proto   Local                Remote

ae0.760                up   down ccc  

The OL (No Ongoing Label) state occurs when the spoke router is incorrectly configured, causing:

1. Neighbor Misconfiguration: The routing-instance points to the router’s own lo0 IP as its neighbor instead of the correct hub router.
2. Encapsulation Issues: Mismatched encapsulation between the spoke and hub routers can also prevent the L2Circuit from coming up.

Correct the Neighbor Configuration: Update the neighbor settings within the VPLS routing-instance to reflect the correct hub router’s IP address.

[edit routing-instances HUB2 protocols vpls mesh-group HUB2]
+    Remote HUB2 lo0 IP address;  # Correct neighbor IP for HUB2
-    neighbor local lo0 IP adddress;  # Previously incorrect neighbor IP

Add the ignore-encapsulation-mismatch Knob: This setting allows the system to ignore minor encapsulation mismatches, which can sometimes prevent the L2Circuit from coming up.

[edit routing-instances HUB2 protocols vpls]

+   ignore-encapsulation-mismatch;

Verify the L2Circuit Status: After making the configuration changes, verify the connection status using the following command:

root@ACX7024-C(HUB2)# run show l2circuit connections

Layer-2 Circuit Connections:

Neighbor: Lo0 interface for remote PE (SPOKE)
  Interface         Type St   Time last up     # Up trans
  ae0.760(vc 123)      rmt  Up   Oct 28 23:06:01 2024      1
   Remote PE: Lo0 interface for remote PE, Negotiated control-word: No
   Encapsulation: ETHERNET
   Incoming label: 23, Outgoing label: 25
   Local interface: ae0.760, Status: Up, Encapsulation: VLAN