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Chapter 23 VLAN Stacking
MES-3528 User’s Guide
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Note: When you enable VLAN stacking on the Switch, the Access Port and Tunnel
Port should be in the same customer VLAN (static VLAN) to communicate with
each other.
23.3 VLAN Tag Format
A VLAN tag (service provider VLAN stacking or customer IEEE 802.1Q) consists of
the following three fields.
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.
SP TPID (Service Provider Tag Protocol Identifier) is the service provider VLAN
stacking tag type.
• If the VLAN stacking port role is Tunnel Port, then the Switch discards 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. The Switch adds the SP TPID tag to all outgoing frames sent
through the Tunnel Port on 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 single-tagged IEEE 802.1Q
frame (customer) and a “double-tagged” 802.1Q frame (service provider) is
shown next.
Table 51 VLAN Tag Format
TPID Priority VID