Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 782)

732 Brocade 6910 Ethernet Access Switch Configuration Guide
53-1002581-01
IEEE 802.1Q Tunneling
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3. After packet classification through the switching process, the packet is written to memory with
one tag (an outer tag) or with two tags (both an outer tag and inner tag).
4. The switch sends the packet to the proper egress port.
5. 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 packets will have two tags.
Layer 2 Flow for Packets Coming into a Tunnel Uplink Port
An uplink port receives one of the following packets:
• Untagged
• One tag (CVLAN or SPVLAN)
• Double tag (CVLAN + SPVLAN)
The ingress process does source and destination lookups. If both lookups are successful, the
ingress process writes the packet 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 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.