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INS_CWGE24MS2_REV–
10/05/16 PAGE 112
INSTALLATION AND OPERATION MANUAL
CWGE24MS2
TECH SUPPORT: 1.888.678.9427
VID is the VLAN ID. SP VID is the VID for the second or outer (service provider’s) VLAN tag. CVID is
the VID for the first or inner (Customer’s) VLAN tag.
The frame formats for an untagged Ethernet frame; a single-tagged 802.1Q frame (customer) and
a “double-tagged” 802.1Q frame (service provider) are shown as following.
untagged
frame
DA
SA
Len or
Etype
Data
FCS
single-
tagged
frame
DA
SA
TPID
P
VID
Len or
Etype
Data
FCS
double-
tagged
frame
DA
SA
Tunnel
TPID
P
VID
TPID
P
VID
Len or
Etype
Data
FCS
DA: Destination Address
SA: Source Address
Tunnel TPID: Tag Protocol Identifier added on a tunnel port
P: 802.1p priority
VID: VLAN ID
Len or Etype: Length or Ethernet frame type
Data: Frame data
FCS: Frame Check Sequence
VLAN Stacking Port Roles
Each port can have three VLAN stacking “roles”, Normal, Access Port and Tunnel Port.
» Select Normal for “regular” (non-VLAN stacking) IEEE 802.1Q frame switching.
» Select Access Port for ingress ports on the service provider’s edge devices. The incoming
frame is treated as “untagged”, so a second VLAN tag (outer VLAN tag) can be added.
» Select Tunnel Port for egress ports at the edge of the service provider’s network. All VLANs
belonging to a customer can be aggregated into a single service provider’s VLAN (using the
outer VLAN tag defined by SP VID).
NOTE: In order to have the double tagged frames switching correctly, user has to configure a
service provider’s VLAN (SPVLAN) on the Q-in-Q switch. Then, the double tagged frames
can be switched according to the SP VID. The SPVLAN should include all the related
Tunnel and Access ports. Also, user has to configure the Tunnel posts as tagged ports and
the Access ports as untagged ports.