This feature is supported only in the ASR 9000 Ethernet Line Card.
Note
Layer 2 Protocol Tunneling
Layer 2 Protocol Tunneling (L2PT) is a Cisco proprietary protocol for tunneling Ethernet protocol frames
across Layer 2 (L2) switching domains.
When an L2 protocol frame enters the interface of an L2 switching device, the switch or router performs one
of these actions on the frame:
• forward—the frame is switched or routed with no exceptional handling.
• drop—the frame is discarded on the router.
• terminate—the router recognizes that the frame is an L2 protocol frame, and therefore sends it to the
router's control plane for protocol processing.
• tunnel—the router encapsulates the frame to hide its identity as a protocol frame. This prevents the frame
from being terminated on other routers. The opposite end of the tunnel performs a decapsulation, returning
the frame to its original state.
L2PT Features
The Cisco ASR 9000 Series Routers offer these functions:
• Tunnels these protocols:
• Cisco Discovery Protocol (CDP)
• Spanning Tree Protocol (STP and its derivatives)
• Virtual Trunking Protocol (VTP)
• Supports these modes of tunneling
• Forward
• Reverse
• L2PT encapsulates and decapsulates protocol frames that have VLAN headers.
• Supports capability of handling enormous frame rates. The Cisco ASR 9000 Series Routers perform
L2PT encapsulation and decapsulation at the interface line rates.
There are no dedicated L2PT counters. There are no L2PT-specific adjustments for QoS or other miscellaneous
parameters.
Note
L2PT in the Forward Mode
Figure below shows L2PT configured in the forward mode.
L2VPN and Ethernet Services Configuration Guide for Cisco ASR 9000 Series Routers, IOS XR Release 6.3.x
40
Ethernet Features
Layer 2 Protocol Tunneling
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