Forwarding Vlan, Pppoe Over Vlan - Enterasys Security Router X-PeditionTM User Manual

The reserved Tag Type denotes the associated Ethernet frame type of the VLAN Tag while the
remaining 16 tag bits comprise this control data:
• a 3-bit value indicating the user priority of the Ethernet frame for QoS purposes
• a 1-bit Canonical Format Indicator (CFI) denoting the presence of a Routing Information Field
• a 12-bit VLAN Identifier (VLAN ID) used for network assignment
The XSR lets you configure up to 4094 VLANs using the
reserved. VLAN ID 0 is used to represent the default VLAN. VLANs provide for eight priority
levels but the XSR does not act on priority bits. Any VLAN packets originating from the XSR are
assigned a priority of 0.
Figure 5-2 depicts a typical VLAN routing setup. The LAN that a device belongs to depends on
the settings of the interfaces on the VLAN switch rather than the actual systems layout.
WAN
XSR

Forwarding VLAN, PPPoE over VLAN

It is possible for a single physical Ethernet interface to support a mixture of Ethernet, PPPoE,
Ethernet VLAN, and PPPoE over VLAN traffic, as illustrated in
GigabitEthernet sub-interfaces 3.1 - 3.4 are all sub-interfaces associated with different VLAN IDs.
Figure 5-1
802.1Q Tag Type
Figure 5-2 Typical Configuration of VLAN Routing
Physical layout
VLAN Switches
Logical layout
802.1Q VLAN Tag
Priority CFI VLAN Identifier
vlan command, with IDs 0 and 4095
VLAN 200
VLAN 100
Figure
IP Routing Protocols
VLAN 300
5-3. Note that
XSR User's Guide 5-19