Etic Telecom XLAN+ Series, Setup Manual

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SETUP
Page 34
DOC_DEV_XS_Setup guide_C
9 VLAN
9.1 Overview
VLAN function
The VLAN technology conform to the IEEE 802.1Q norm makes possible to transmit up to 4096 Ethernet
networks over the same physical Ethernet layer.
The devices belonging to the same Ethernet VLAN can exchange Ethernet frames with one another but cannot
exchange frames with devices belonging to another VLAN except if a level 3 switch or an equivalent device
makes possible to bridge that VLANs.
Ethernet ports
When we speak of an Ethernet port of an XS, we speak not only of 10/100 BT Ethernet ports, but also of the
SHDSL ports.
All SHDSL ports are supposed to be a unique SHDSL port.
Principles of operations
A particular field of each Ethernet frame stores the VLAN identity (VID) to which the frame belongs.
When that field stores the VLAN ID, one says the frame is tagged.
How are Ethernet frames tagged and untagged ?
An Ethernet frame can be tagged by the device which produces it.
Otherwise, the Ethernet frame is tagged by the switch to which the device is connected.
Reciprocally, the VLAN ID of an Ethernet frame can be removed by the Ethernet switch before being transmitted
to the Ethernet device or can be transmitted tagged to the device.
The switch filters the Ethernet frames according to their VLAN ID
When they come into the switch on an Ethernet port, Ethernet frames are tagged with the VLAN ID assigned to
that Ethernet port.
When it is received by the switch, a tagged Ethernet frame can only come out to an Ethernet port, if the VLAN
ID assigned to that port is the same as the VLAN ID of the Ethernet frame.
Html administration server and the serial gateway
If the VLAN function is enabled, Ethernet frames produced by the html administration server and the serial
gateway are tagged with a particular VLAN.
If the html administration server and the serial gateway do not belong to the same VLAN, a separate IP address
must be assigned to the serial gateway
Setting up the VLAN function
The VLAN set up is divided in two parts : The Egress policy set up and the Ingress policy set up.
•
The Egress policy consists in registering the authorized VLAN IDs and defining which Ethernet ports belong
to each VLAN.
• The Ingress policy consists in defining which process must be applied to each Ethernet frames going into
the switch : Tagging the frame with a VLAN ID or leaving the frames untagged etc …