Transport Tunnel Termination

Transport tunnel termination applies to packets with destination MAC address within the chassis MAC address and considered “destined to us.”

The chassis MAC address is a non-configurable parameter and is configured in the data path at boot-up time.

Transport tunnel termination supports decapsulation of GRE or ERSPAN headers. To terminate destination MAC in the packet:

The packet is checked for an IPv4 or IPv6 address and type of encapsulation.
If the source IPv4 or IPv6 address and configured encapsulation type match, an intermediate SAP is assigned to the packet and the packet is marked for dropping.
The intermediate SAP is matched along with tunnel or encapsulation type and tunnel ID.
If all the parameters match, it is considered a successful termination and from it, a network SAP is derived.

The packet is marked for decapsulation of transport header, and as the transport header is removed, the scope is automatically shifted to the next header in the packet.

The transport tunnel terminated packets are classified according to non-transport tunnel parameters configured as part of the ingress group. Based on ingress group configurations, the inner header is terminated, scope is shifted to the next header, or packets are classified and SAP is updated in the packet metadata to inner SAP (tunnel SAP). For transport packets, both transport (transport header termination) and non-transport configuration (decapsulate outer header, scope-shift operations, or non-transport tunnel classification) are applied and packet classification is done based on both configurations.

In terminate mode, trasport header is decapsulated. Further classification is done on outer header based on ingress group configuration to assign tunnel SAP.

In scope-shift mode, scope shifts to inner header and outer header is not terminated.

In no-op mode, neither scope shifts to inner header nor outer header is decapsulated. Only packet classification is done.