Extreme networks Summit1 Manuale Utente

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 illustrates 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.

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.

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.

Accounting

Engineering

Switch 1

Switch 2

Summit.bk : 5VLAN.FM  Page 5  Thursday, June 18, 1998  9:27 AM