Planet Technology SGSD-1022 - Manual (Page 190)

User’s Manual of SGSD-1022 / SGSD-1022P
SGSW-2840 / SGSW-2840P
190
to memory. Then the egress process transmits the packet. Packets entering a QinQ uplink port are processed in the following
manner:
1. If incoming packets are untagged, the PVID VLAN native tag is added.
2. If the ether-type of an incoming packet (single or double tagged) is not equal to the TPID of the uplink port, the VLAN tag is
determined to be a Customer VLAN (CVLAN) tag. The uplink port’s PVID VLAN native tag is added to the packet. This
outer tag is used for learning and switching packets within the service provider’s network. The TPID must be configured on
a per port basis, and the verification cannot be disabled.
3. If the ether-type of an incoming packet (single or double tagged) is equal to the TPID of the uplink port, no new VLAN tag is
added. If the uplink port is not the member of the outer VLAN of the incoming packets, the packet will be dropped when
ingress filtering is enabled. If ingress filtering is not enabled, the packet will still be forwarded. If the VLAN is not listed in the
VLAN table, the packet will be dropped.
4. After successful source and destination lookups, the packet is double tagged. The Managed Switch uses the TPID of
0x8100 to indicate that an incoming packet is double-tagged. If the outer tag of an incoming double-tagged packet is equal
to the port TPID and the inner tag is 0x8100, it is treated as a double-tagged packet. If a single-tagged packet has 0x8100
as its TPID, and port TPID is not 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. Avoid 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”).
2. Set the Tag Protocol Identifier (TPID) value of the tunnel access 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