Assigning Ports To Vlans - Alcatel OS-LS-6224 User Manual

VLANs inherently provide a high level of network security since traffic must pass
through a configured Layer 3 link to reach a different VLAN.
This switch supports the following VLAN features:
• Up to 255 VLANs based on the IEEE 802.1Q standard
• Distributed VLAN learning across multiple switches using explicit or implicit tagging
and GVRP protocol
• Port overlapping, allowing a port to participate in multiple VLANs
• End stations can belong to multiple VLANs
• Passing traffic between VLAN-aware and VLAN-unaware devices
• Priority tagging

Assigning Ports to VLANs

Before enabling VLANs for the switch, you must first assign each port to the VLAN
group(s) in which it will participate. By default all ports are assigned to VLAN 1 as
untagged ports. Add a port as a tagged port if you want it to carry traffic for one or
more VLANs, and any intermediate network devices or the host at the other end of
the connection supports VLANs. Then assign ports on the other VLAN-aware
network devices along the path that will carry this traffic to the same VLAN(s), either
manually or dynamically using GVRP. However, if you want a port on this switch to
participate in one or more VLANs, but none of the intermediate network devices nor
the host at the other end of the connection support VLANs, then you should add this
port to the VLAN as an untagged port.
Note:
VLAN-tagged frames can pass through VLAN-aware or VLAN-unaware network
interconnection devices, but the VLAN tags should be stripped off before passing it
on to any end-node host that does not support VLAN tagging.
VLAN Classification
When the switch receives a frame, it classifies the frame in one of two ways. If the
frame is untagged, the switch assigns the frame to an associated VLAN (based on
the default VLAN ID of the receiving port). But if the frame is tagged, the switch uses
the tagged VLAN ID to identify the port broadcast domain of the frame.
Port Overlapping
Port overlapping can be used to allow access to commonly shared network
resources among different VLAN groups, such as file servers or printers.
Untagged VLANs
Untagged (or static) VLANs are typically used to reduce broadcast traffic and to
increase security. A group of network users assigned to a VLAN form a broadcast
domain that is separate from other VLANs configured on the switch. Packets are
forwarded only between ports that are designated for the same VLAN. Untagged
VLANs can be used to manually isolate user groups or subnets. However, you
should use IEEE 802.3 tagged VLANs with GVRP whenever possible to fully
automate VLAN registration.
Configuring VLANs
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