Extreme Networks ExtremeWare XOS 11.3, Руководство пользователя

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Types of VLANs
ExtremeWare XOS 11.3 Concepts Guide
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Figure 7: Two port-based VLANs spanning two switches
VLAN Accounting spans system 1 and system 2 by way of a connection between system 2, port 29 and
system 1, slot 1, port 6. VLAN Engineering spans system 1 and system 2 by way of a connection between
system 2, port 32, and system 1, slot 8, port 6.
Using this configuration, you can create multiple port-based VLANs that span multiple switches, in a
daisy-chained fashion. Each switch must have a dedicated port for each VLAN. Each dedicated port
must be connected to a port that is a member of its VLAN on the next switch.
Tagged VLANs
Tagging is a process that inserts a marker (called a tag ) into the Ethernet frame. The tag contains the
identification number of a specific VLAN, called the VLANid (valid numbers are 1 to 4094) .
NOTE
The use of 802.1Q tagged packets may lead to the appearance of packets slightly bigger than the current IEEE
802.3/Ethernet maximum of 1,518 bytes. This may affect packet error counters in other devices and may also lead
to connectivity problems if non-802.1Q bridges or routers are placed in the path.
Uses of Tagged VLANs
Tagging is most commonly used to create VLANs that span switches. The switch-to-switch connections
are typically called
trunks . Using tags, multiple VLANs can span multiple switches using one or more
trunks. In a port-based VLAN, each VLAN requires its own pair of trunk ports, as shown in Figure 7 .
Using tags, multiple VLANs can span two switches with a single trunk.
EX_063
System 1
System 2
Accounting Engineering