8-10
Cisco ONS 15310-CL and Cisco ONS 15310-MA Ethernet Card Software Feature and Configuration Guide R8.5
78-18133-01
Chapter 8 Configuring IEEE 802.1Q Tunneling and Layer 2 Protocol Tunneling on the ML-Series Card
Configuring Layer 2 Protocol Tunneling
protocol tunneling for CDP, STP, and VTP at the interface and subinterface level. Multiple STP (MSTP)
tunneling support is achieved through subinterface protocol tunneling. The ML-Series cards con nected
to the customer switch perform the tunneling process.
When the Layer 2 PDUs that entered the inbound ML-Series switch through the tunnel port exit the
switch through the trunk port into the service-provider network, the swit ch overwrites the customer
PDU-destination MAC address with a well-known Cisco proprietary multicast address
(01-00-0c-cd-cd-d0). If IEEE 802.1Q tunneling is e nabled, packets are also double-tagged; the outer tag
is the customer metro tag and the inner tag is the customer VLAN tag. The core switches ignore the inner
tags and forward the packet to all trunk ports in the same metro VLAN. The ML-Series switches on the
outbound side restore the proper Layer 2 protocol and MAC address information and forward the
packets. Therefore, the Layer 2 PDUs are kept intact and delivered across the service-provider
infrastructure to the other side of the customer network.
This section contains the following information about configuring Laye r 2 protocol tunneling:
• Default Layer 2 Protocol Tunneling Configuration, page 8-10
• Layer 2 Protocol Tunneling Configuration Guidelines, page 8-10
• Configuring Layer 2 Tunneling on a Port, page 8-11
• Configuring Layer 2 Tunneling Per-VLAN, page 8-12
• Monitoring and Verifying Tunneling Status, page 8-12
Default Layer 2 Protocol Tunneling Configuration
Table 8-2 shows the default Layer 2 protocol tunneling configuration.
Layer 2 Protocol Tunneling Configuration Guidelines
These are some configuration guidelines and operating chara cteristics of Layer 2 protocol tunneling:
• The ML-Series card supports Per-VLAN Protocol Tunneling (PVPT), which allows protoc ol
tunneling to be configured and run on a specific subinterface (VLAN). PVPT configuration is done
at the subinterface level.
• PVPT should be configured on VLANs that carry multi-session transport (MST) BPDUs on the
connected devices.
• The ML-Series card supports tunneling of CDP and STP (including MSTP and VTP protocols).
Protocol tunneling is disabled by default but can be enabled for the i ndividual protocols on
IEEE 802.1Q tunnel ports or on specific VLANs.
Table 8-2 Default Layer 2 Protocol Tunneling Configuration
Feature Default Setting
Layer 2 protocol tunneling Disabled for CDP, STP, and VTP.
Class of service (CoS) value If a CoS value is configured on the interface for data
packets, that value is the default used for Layer 2 PDUs. If
none is configured, there is no default. This allows existing
CoS values to be maintained, unless the user configures
otherwise.