Tag: L2VPN

Tunneling Technologies: L2TPv3

L2VPNs featured an expansion with the Layer 2 Tunneling Protocol version 3 feature.  L2TPv3 provides enhancements to L2TP to tunnel any L2Payload over L2tP by defining how L2TP tunnels L2 payloads over an IP core by using L2VPNs.

L2TPv3 uses protocol ID 115.

In order for L2TPv3 to work you must have CEF enabled and that the loopback interface has a valid IP address that is reachable from remote PE devices at the other end of an L2TPv3 control channel


Tunneling Technologies: L2VPN Tagged Mode and Raw Mode

Tagged Mode

This mode references 802.1Q tags across L2VPN pseudowires.  These tags are only significant to local and endpoint devices.  Service providers must preserve the original VLAN Tag IDs passed to them from the local endpoint to the remote endpoint.

Tagged mode pseudowires have a type 0x0004, and every frame sent across a PW must have a unique VLAN for each customer.  this is called the service delimiting VLAN tag.

If a frame is received from the attachment circuit and its missing a service-delimiting VLAN the PE must prepend the frame with a dummy VLAN tag before sending the frame on the PW.

Raw Mode

In Raw mode pseudowires, the service delimiting tag has no significance.  This mode has pseudowire type 0x0005, Raw mode dictates that any service delimiting tags must be removed before being transported across the L2VPN PW.


Tunneling Technologies: Layer 2 VPN

This service offered by ISPs allows two remote locations to be logically connected to each other across a layer 2 connection over a carriers network.  This is typically used for customers to manage their own network as L2VPN is the simplest solution where a client wants to manage their own protocols, IP management, QoS, everything.

L2VPN solutions are referred to as pseudowire connections.

Ethernet Pseudowires allow ethernet frames to traverse MPLS clouds.  the service provider extends layer 2 adjacency between sites, allowing spanning tree to run across links. This is referred to as Emulated Sevice.

Ethernet pseudowires has two modes:

  • Raw mode
  • Tagged mode