Edge-Core ECS4660-28F, Руководство по управлению, Страница: 1361 / 2020

C
HAPTER
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| VLAN Commands
Configuring L2CP Tunneling
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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.
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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
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connected to the same metro VLAN).
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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
◆
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)
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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.
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with the destination address 01-80-C2-00-00-01~0A (S-VLAN tag),
it is filtered, decapsulated, and processed locally by the switch if the
protocol is supported.
◆
When a protocol packet is received on an access port (i.e., an 802.1Q
trunk port connecting the edge switch to the local customer network)
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with the destination address 01-80-C2-00-00-00,0B~0F (C-VLAN),
and
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L2PT is enabled on the port, the frame is forwarded to all QinQ
uplink ports and QinQ access ports on which L2PT is enabled for
that protocol in the same S-VLAN.
■
L2PT is disabled on the port, the frame is decapsulated and
processed locally by the switch if the protocol is supported.
27. Access ports in this context are 802.1Q trunk ports.