Chapter 21
| VLAN Commands
Configuring L2PT Tunneling
– 610 –
â–
IPv6 multicast addresses (with prefix 33-33-33)
â–
Addresses used by the spanning tree protocol.
Default Setting
01-12-CF-.00-00-02, proprietary tunnel address
Command Mode
Global Configuration
Command Usage
â—† When L2PT is not used, protocol packets (such as STP) are flooded to 802.1Q
access ports on the same edge switch, but filtered from 802.1Q tunnel ports.
This creates disconnected protocol domains in the customer’s network.
â—† L2PT can be used to pass various types of protocol packets belonging to the
same customer transparently across a service provider’s network. In this way,
normally segregated network segments can be configured to function inside a
common protocol domain.
â—† L2PT encapsulates protocol packets entering ingress ports on the service
provider’s edge switch, replacing the destination MAC address with a
proprietary MAC address (for example, the spanning tree protocol uses 10-12-
CF-00-00-02), a reserved address for other specified protocol types (as defined
in IEEE 802.1ad – Provider Bridges), or a user-defined address. All intermediate
switches carrying this traffic across the service provider’s network treat these
encapsulated packets in the same way as normal data, forwarding them across
to the tunnel’s egress port. The egress port decapsulates these packets, restores
the proper protocol and MAC address information, and then floods them onto
the same VLANs at the customer’s remote site (via all of the appropriate tunnel
ports and access ports
14
connected to the same metro VLAN).
◆ The way in which L2PT processes packets is based on the following criteria – (1)
packet is received on a QinQ uplink port, (2) packet is received on a QinQ access
port, or (3) received packet is Cisco-compatible L2PT (i.e., as indicated by a
proprietary MAC address).
Processing protocol packets defined in IEEE 802.1ad – Provider Bridges
â—† When an IEEE 802.1ad protocol packet is received on an uplink port (i.e., an
802.1Q tunnel ingress port connecting the edge switch to the service provider
network)
â–
with the destination address 01-80-C2-00-00-00,0B~0F (C-VLAN tag), it is
forwarded to all QinQ uplink ports and QinQ access ports in the same S-
VLAN for which L2PT is enabled for that protocol.
14. Access ports in this context are 802.1Q trunk ports.
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