Extreme Networks Summit1 manual Tagged Vlans, 3Two port-based VLANs spanning two Switches

TYPES OF VLANS

Figure 5-3illustrates two VLANs spanning two switches. On Switch 1, ports 1-4 are part of VLAN Accounting; ports 5 - 8 are part of VLAN Engineering. On Switch 2, ports 1-4 are part of VLAN Accounting; ports 5 - 8 are part of VLAN Engineering. VLAN Accounting spans Switch 1 and Switch 2 by way of a connection between Switch 1 port 2 and Switch 2 port 4. VLAN Engineering spans Switch 1 and Switch 2 by way of a connection between Switch 1 port 5 and Switch 2 port 8.

AccountingEngineering

		1			8
2	3	4	5	6	7

Switch 1

		1			8
2	3	4	5	6	7

Switch 2

Figure 5-3:Two port-based VLANs spanning two Switches

Using these steps, you can create multiple VLANs that span multiple switch es, 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 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.

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 1518 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.

SUMMIT SWITCH INSTALLATION AND USER GUIDE 5-5