Cabletron Systems SmartSTACK ELS10-27TX Supplement Manual - A.2.1  Vlan Id

A-2

ELS10-27TX VLAN Configuration

If the ELS10-27TX is so configured, and, if the frame does not already contain a 

tag, a VLAN identifier is placed in a tag which is appended to frames as they are 

received by the switch. Within the switch and between switches compliant with 

IEEE 802.1Q, these identifiers are used to control the destination of all frames, 

preventing them from being flooded to all connected stations and interfaces. When 

frames are forwarded to destination end stations, the tag may or may not be 

stripped off, depending on the configuration of the switch port.

By using 802.1Q tagged VLANs, users from physically dispersed locations can be 

formed into groups by assigning them to specific VLANs. Broadcast, Unicast and 

multicast traffic for these specific VLANs can be directed across the network 

without being radiated out to stations that are not members of the same VLANs. 

Up to 32 different VLANs can be specified by the 802.1Q tag. This 

implementation is non-intrusive to end-station applications and the associated 

clients. Both tagged and non-tagged as defined can function properly in the 

environment.

A.2 ELS10-27TX VLAN CONFIGURATION

VLAN operation on the ELS10-27TX is disabled by default.You must configure 

all VLANs, prior to using them. When VLANs are enabled, all frames are 

transferred internally through the switch with a VLAN tag. This tag may already 

be on the frame entering the switch, or it may be added to the frame by the switch. 

VLAN information already existing on frames entering the switch is 

automatically handled by the switch. The ELS10-27TX uses VLAN information 

from tagged frames and appropriately switches frames out the proper ports based 

on this information. This configuration can be made either through the VLAN 

Menu in the console interface or via SNMP. The parameters used to configure 

VLANs on the ELS10-27TX are explained below.

If tag-unaware devices are to be supported, access ports and default VLAN IDs 

for the ports must be configured.

A.2.1  VLAN ID

The VLAN ID is used to uniquely identify different VLANs on a network. The 

VLAN ID information is contained in the 802.1Q tag header on a frame, and so 

identifies the VLAN to which a frame belongs. The ELS10-27TX recognizes 

VLAN IDs in the tags on frames entering the switch, and can also add tags with 

an appropriate VLAN ID to untagged frames.