L2VPN Route Recursion to an SR Tunnel

Figure 1 shows a typical VPLS network. On the network, users in different geographical regions communicate with each other through different PEs. From the perspective of users, a VPLS network is a Layer 2 switched network that allows them to communicate with each other in a way similar to communication over a LAN. After VPLS route recursion to an SR tunnel is configured, virtual connections are established between the sites of each VPN, and public SR tunnels are established, Layer 2 packets can be forwarded over the SR tunnels.

VPLS Route Recursion to an SR LSP

As shown in Figure 1, the process of VPLS route recursion to an SR LSP is as follows:

• CE1 sends a packet with Layer 2 encapsulation to PE1.
• PE1 establishes an E2E SR LSP with PE2.
• A tunnel policy is configured on PE1 for SR LSP selection, and VSI forwarding entries are associated with SR forwarding entries.
• After receiving the packet, PE1 searches for a VSI entry and selects a tunnel and PW based on the entry. Then, PE1 adds an outer LSP label and inner VC label to the packet based on the selected tunnel and PW, performs Layer 2 encapsulation, and forwards the packet to PE2.
• PE2 receives the packet from PE1 and decapsulates it.
• PE2 forwards the original packet to CE2.

Figure 1 VPLS route recursion to an SR LSP

The processes of HVPLS route recursion to an SR LSP and VLL route recursion to an SR LSP are similar to the process of VPLS route recursion to an SR LSP and therefore are not described.

VPLS Route Recursion to an SR-MPLS TE Tunnel

As shown in Figure 2, the process of VPLS route recursion to an SR-MPLS TE tunnel is as follows:

• CE1 sends a packet with Layer 2 encapsulation to PE1.
• PE1 establishes an E2E SR-MPLS TE tunnel with PE2.
• A tunnel policy is configured on PE1 for SR-MPLS TE tunnel selection, and VSI forwarding entries are associated with SR forwarding entries.
• After receiving the packet, PE1 searches for a VSI entry and selects a tunnel and PW based on the entry. Then, PE1 adds an outer SR-MPLS TE tunnel label and inner VC label to the packet based on the selected tunnel and PW, performs Layer 2 encapsulation, and forwards the packet to PE2.
• PE2 receives the packet from PE1 and decapsulates it.
• PE2 forwards the original packet to CE2.

Figure 2 VPLS route recursion to an SR-MPLS TE tunnel

The processes of HVPLS route recursion to an SR-MPLS TE tunnel and VLL route recursion to an SR-MPLS TE tunnel are similar to the process of VPLS route recursion to an SR-MPLS TE tunnel and therefore are not described.