Enterasys els10-27tx Benutzerhandbuch

A-1

The ELS10-27TX supports IEEE 802.1Q-compliant virtual LANs (VLANs). This 
capability provides a highly efficient architecture for establishing VLANs within a 
network and for controlling broadcast/multicast traffic between workgroups. 
Central to this capability is an explicit frame tagging approach for carrying VLAN 
information between interconnected network devices. 

With frame tagging, a four-byte data tag field is appended to frames that cross the 
network. The tag identifies which VLAN the frame belongs to. The tag may be 
added to the frame by the end station itself or by a network device, such as a switch. 

In the example in Figure A-1 below, the workstations attached to the top switch are 
members of the same two VLANs as the workstations attached to the bottom 
switch. The 802.1Q tags are used to carry VLAN information in the frames 
traveling between the two switches.

* Note       is true if it does not have a tag and is a hybrid port, or the port is an 
   access port.

* Note       is only stripped, if the hybrid port and the tag in the packet matches the 

PVID or is an access port.

VLAN Y

VLAN Y

802.1Q tag added

by Incoming port*

802.1Q tag carries

VLAN Identifier

802.1Q used by

switch to determine

VLAN, then stripped

by forwarding port*

1

2

3

VLAN X

VLAN X