ZyXEL ES-3148 Guida Utente
Chapter 21 VLAN Stacking
ES-3148 User’s Guide
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21.3 VLAN Tag Format
A VLAN tag (service provider VLAN stacking or customer IEEE 802.1Q) consists of the
following three fields.
following three fields.
Type is a standard Ethernet type code identifying the frame and indicates that whether the
frame carries IEEE 802.1Q tag information. SP TPID (Service Provider Tag Protocol
Identifier) is the service provider VLAN stacking tag type. Many vendors use 0x8100 or
0x9100.
TPID (Tag Protocol Identifier) is the customer IEEE 802.1Q tag.
frame carries IEEE 802.1Q tag information. SP TPID (Service Provider Tag Protocol
Identifier) is the service provider VLAN stacking tag type. Many vendors use 0x8100 or
0x9100.
TPID (Tag Protocol Identifier) is the customer IEEE 802.1Q tag.
• If the VLAN stacking port role is Access Port, then the Switch adds the SP TPID tag to
all incoming frames on the service provider's edge devices (1 and 2 in the VLAN stacking
example figure).
example figure).
• If the VLAN stacking port role is Tunnel Port, then the Switch only adds the SP TPID
tag to all incoming frames on the service provider's edge devices (1 and 2 in the VLAN
stacking example figure) that have an SP TPID different to the one configured on the
Switch. (If an incoming frame’s SP TPID is the same as the one configured on the Switch,
then the Switch will not add the tag.)
stacking example figure) that have an SP TPID different to the one configured on the
Switch. (If an incoming frame’s SP TPID is the same as the one configured on the Switch,
then the Switch will not add the tag.)
Priority refers to the IEEE 802.1p standard that allows the service provider to prioritize traffic
based on the class of service (CoS) the customer has paid for.
based on the class of service (CoS) the customer has paid for.
• On the Switch, configure priority level of inner IEEE 802.1Q tag in the Port Setup screen.
• "0" is the lowest priority level and "7" is the highest.
VID is the VLAN ID. SP VID is the VID for the second (service provider’s) VLAN tag.
21.3.1 Frame Format
The frame format for an untagged Ethernet frame, a single-tagged 802.1Q frame (customer)
and a “double-tagged” 802.1Q frame (service provider) is shown next.
Configure the fields as highlighted in the Switch VLAN Stacking screen.
and a “double-tagged” 802.1Q frame (service provider) is shown next.
Configure the fields as highlighted in the Switch VLAN Stacking screen.
Table 52 VLAN Tag Format
Type
Priority
VID
Table 53 Single and Double Tagged 802.11Q Frame Format
DA
SA
Len/
Etype
Data
FCS Untagged
Ethernet frame
DA
SA
TPID Priority VID Len/
Etype
Data
FCS IEEE 802.1Q
customer
tagged frame
DA SA SPTPID Priority VID
TPID Priority VID
Len/
Etype
Data
FCS Double-tagged
frame
Table 54 802.1Q Frame
DA
Destination Address
Priority
802.1p Priority
SA
Source Address
Len/
Etype
Length and type of Ethernet frame