SMC Networks SMC8126L2 Management Manual page 180

3
Configuring the Switch
0x8100, a new VLAN tag is added and it is also treated as double-tagged packet.
5. If the destination address lookup fails, the packet is sent to all member ports of
the outer tag's VLAN.
6. After packet classification, the packet is written to memory for processing as a
single-tagged or double-tagged packet.
7. The switch sends the packet to the proper egress port.
8. If the egress port is an untagged member of the SPVLAN, the outer tag will be
stripped. If it is a tagged member, the outgoing packet will have two tags.
Configuration Limitations for QinQ
• The native VLAN of uplink ports should not be used as the SPVLAN. If the SPVLAN
is the uplink port's native VLAN, the uplink port must be an untagged member of
the SPVLAN. Then the outer SPVLAN tag will be stripped when the packets are
sent out. Another reason is that it causes non-customer packets to be forwarded
to the SPVLAN.
• Static trunk port groups are compatible with QinQ tunnel ports as long as the QinQ
configuration is consistent within a trunk port group.
• The native VLAN (VLAN 1) is not normally added to transmitted frames. Avoiding
using VLAN 1 as an SPVLAN tag for customer traffic to reduce the risk of
misconfiguration. Instead, use VLAN 1 as a management VLAN instead of a data
VLAN in the service provider network.
• There are some inherent incompatibilities between Layer 2 and Layer 3 switching:
- Tunnel ports do not support IP Access Control Lists.
- Layer 3 Quality of Service (QoS) and other QoS features containing Layer 3
information are not supported on tunnel ports.
- Spanning tree bridge protocol data unit (BPDU) filtering is automatically disabled
on a tunnel port.
General Configuration Guidelines for QinQ
1. Configure the switch to QinQ mode (see "Enabling QinQ Tunneling on the
Switch" on page 3-137).
2. Create a Service Provider VLAN, also referred to as an SPVLAN (see "Creating
VLANs" on page 3-128).
3. Configure the QinQ tunnel access port to 802.1Q Tunnel mode (see "Adding an
Interface to a QinQ Tunnel" on page 3-138).
4. Set the Tag Protocol Identifier (TPID) value of the tunnel port. This step is
required if the attached client is using a nonstandard 2-byte ethertype to identify
802.1Q tagged frames. The default ethertype value is 0x8100. (See "Adding an
Interface to a QinQ Tunnel" on page 3-138.)
5. Configure the QinQ tunnel access port to join the SPVLAN as an untagged
member (see "Adding Static Members to VLANs (VLAN Index)" on page 3-129).
6. Configure the SPVLAN ID as the native VID on the QinQ tunnel access port (see
"Configuring VLAN Behavior for Interfaces" on page 3-132).
7. Configure the QinQ tunnel uplink port to 802.1Q Tunnel Uplink mode (see
3-136