Chapter 23 VLAN Stacking
23.3 VLAN Tag Format
A VLAN tag (service provider VLAN stacking or customer IEEE 802.1Q) consists of the following three fields.
Table 53 VLAN Tag Format
TPID | Priority | VID |
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TPID (Tag Protocol Identifier) is a standard Ethernet type code identifying the frame and indicates that whether the frame carries IEEE 802.1Q tag information. The value of this field is 0x8100 as defined in IEEE 802.1Q. Other vendors may use a different value, such as 0x9100.
Tunnel TPID is the VLAN stacking tag type the Switch adds to the outgoing frames sent through a Tunnel Port of the service provider's edge devices (1 and 2 in the VLAN stacking example figure).
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.
•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.
23.3.1 Frame Format
The frame format for an untagged Ethernet frame, a
Configure the fields as highlighted in the Switch VLAN Stacking screen.
Table 54 Single and Double Tagged 802.11Q Frame Format
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| DA | SA | Len/ | Dat | FCS | Untagged |
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| Etype | a |
| Ethernet |
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| frame |
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| DA | SA | TPI | Priorit | VI | Len/ | Dat | FCS | IEEE 802.1Q |
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| D | y | D | Etype | a |
| customer |
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| tagged |
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| frame |
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D | SA | Tunne | Priori | VI | TPI | Priorit | VI | Len/ | Dat | FCS | Double- |
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| l TPID | ty | D | D | y | D | Etype | a |
| tagged |
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| frame |
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| 199 |
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