GigaSMART Layer 2 GRE Tunnel Encapsulation/Decapsulation

Required License for L2GRE Decapsulation: Base (GigaVUE‑HC2, and GigaVUE‑HC3), Tunneling (GigaVUE‑HC1)Required License for L2GRE Encapsulation: Advanced Tunneling (GigaVUE‑HC2, and GigaVUE‑HC3), Tunneling (GigaVUE‑HC1)

Use GigaSMART Layer 2 (L2) Generic Routing Encapsulation (GRE) tunnel encapsulation to send traffic from one GigaSMART node over the Internet to a second GigaSMART node using L2GRE encapsulation. Use GigaSMART L2GRE tunnel decapsulation at the second GigaSMART node to decapsulate the traffic before sending it to local tool ports.

GigaSMART Layer 2 GRE tunnel encapsulation/decapsulation provides the following:

■   L2GRE tunnel initiation and encapsulation on the tool port at the sending end of the tunnel (for example, at a remote site)
■   L2GRE tunnel termination and decapsulation on the network port at the receiving end of the tunnel (for example, at a main office site)

The GigaSMART at the remote site encapsulates the filtered packets, adds an encapsulation header, and routes it to the main office site. The encapsulation protocol is GRE and the delivery protocol is IP or IPv6, so the encapsulation header consists of Ethernet + IP + GRE or Ethernet + IPv6 + GRE headers.

The parameters of the encapsulated header are user-configurable, such as the IPv4 address of the IP interface on the destination GigaSMART node and the GRE key that identifies the source of the tunnel.

At the remote end, packets are decapsulated, the L2GRE header is stripped off, and packets are sent to the specified tool port.

IP fragmentation and reassembly are supported. Refer to IP Fragmentation and Reassembly on L2GRE and GMIP Tunnels.

Figure 1 L2GRE Tunnel Encapsulation/Decapsulation shows the remote site encapsulating the filtered traffic and routing it to the main office from the remote end.

The encapsulated packet is sent out of the tool port, which is connected to the public network (the Internet). This packet is routed in the public network to reach the main office site. It ingresses at the routed network port of the GigaVUE node at the main office.

The ingress encapsulated packet is then sent to the GigaSMART at the main office, where the packet is decapsulated and sent to the tool port. The received packet’s destination IP is checked against the source IP/IPv6 configured for the network port. If they match, decapsulation is applied. The Ethernet + IP + GRE or Ethernet + IPv6 + GRE header is stripped and the remaining packet is sent to the tool port.

Note:  IPv6 addresses are not supported on SMT-HC1-S (Generation 3 GigaSMART module on GigaVUE-HC1.

Figure 138 L2GRE Tunnel Encapsulation/Decapsulation

For L2GRE tunnel encapsulation/decapsulation configuration examples, refer to GigaSMART Layer 2 GRE Tunnel Encapsulation/Decapsulation and GigaSMART Layer 2 GRE Tunnel Encapsulation/Decapsulation.

For statistics for encapsulated packets, refer to Display L2GRE Tunnel Encapsulation Statistics. For statistics for decapsulated packets, refer to Display L2GRE Tunnel Decapsulation Statistics.