MPLS Tutorial header image

MPLS Tutorial

≡ Menu

Ethernet Port Mode

Ethernet Port Mode:

In this mode both the ends of the pseudo wire (PW) are connected to the Ethernet ports. The port is tunneled pseudo wire (PW) or using local switching. This is also known as AC-to-AC cross connect) switches packets or frames from one AC to another AC are attached to the same PE node.

The pseudo wire is always a type 5 virtual connection (VC).

On the Ingress Provider Edge, the network service provider passes the packets to the pseudo wire termination point, and adds the MPLS (learn MPLS basics) labels to the packets, and sends the packets over the pseudo wire.

Ether Port Moder Packet Flow

Ether-Port-Moder-Packet-Flow

VLAN Mode:

This mode provides VLAN-to-VLAN connectivity. Each VLAN on a customer end to provider-end link can be configured as a separate L2 VPN connection, using either VC type 4 or VC type 5. VC type 5 is the default mode.

On type 4 VCs, on the ingress provider edge, the VLAN tag maps to a particular pseudo wire and the packet is placed on the pseudo wire with the VLAN tag untouched.

On type 5 VCs, on the ingress provider edge that is receiving packets from the customer edge, the network service provider strips off the customer edge VLAN tag before placing the packets on the pseudo wire. On the egress provider edge, the network service provider pushes the VLAN tag onto the protocol stack before it sends the packet to the customer edge.

VLAN Mode Packet Flow

VLAN-Mode-Packet-Flow

In this figure the Ethernet PE associates internal VLAN-tag to the Ethernet port for switching the traffic internally from the ingress port to the PW;however, before placing the traffic intothe PW, it removes the internal VLAN tag. At the egress VLAN PE, the PE associates a VLAN tag to the frames coming off of the PW and after switching the traffic internally, it sends out the traffic off of an Ethernet trunk port. Since the port is in trunk mode, the VLAN PE doesn’t remove the VLAN tag and forwards the frames through the port with the added tag.

QinQ Mode:

In QinQ mode, each customer edge VLAN is carried by a service provider VLAN. Ideally, in QinQmode, the pseudowire should be a Type 5 virtual connection (VC), but Type 4 virtual connections (VCs) are also supported.

On each Ethernet provider edge network, both the customer edge VLAN (inner) and the service provider VLAN (outer) are configured. Both the customer edge VLAN tag and the service provider VLAN tag are service delimiting.

On a Type 4 virtual connection (VC):

  • On aningress provider edge network:

The service provider inserts a service provider tag onto the packet. Pseudowire termination usesthe service provider tag to find the VC on which to send the packet, and pops the tag before placing the packet on the pseudowire.

  • On an egress provider edge network:

Pseudowire termination pushes a locally significant service provider tag onto the packet beforepassing the packet to the network service provider. The network service provider uses this tag to find the customer edge, and pops the tag before sending the packet to the customer edge.

On a Type 5 virtual connection (VC):

  • On an ingress provider edge network:

The ingress provider edge pops the VLAN tag and passes the packet to pseudowire termination.

  • On an egress provider edge network:

Pseudowire termination pushes the customer edge VLAN (inner) tag and the service providerVLAN (outer) tag before passing the packet to the network service provider. The network service provider uses the service provider VLAN (outer) tag to determine the customer edge and pops the tag before sending the packet over the pseudowire.

css.php