Specifications

VLAN Reference Manual (MGCP/NCS Version)
Mediatrix 4100
165
VLAN
You can set various VLAN parameters to control user priority.
 To enable the VLAN configuration:
1. In the qosVlanIeee8021q group of the qosMIB, locate the qosVlanIeee8021qTaggingEnable
variable.
2. Set the value of this parameter to enable.
The VLAN configuration is enabled.
3. Locate the following variables:
• qosVlanIeee8021qVirtualLanID
• qosVlanIeee8021qDefaultUserPriority
You can also use the priorities set in “
IEEE 802.1q” on page 164 Step 3 without putting the Mediatrix
4100 in a VLAN. To do so, you must set the qosVlanIeee8021qTaggingEnable variable to enable
and the qosVlanIeee8021qVirtualLanID variable to 0. This is a null VLAN ID, which indicates that
the tag header contains only priority information; no VLAN identifier is present in the frame.
4. Set the value of these variables.
5. Restart the Mediatrix 4100 so that the changes may take effect.
For more information, please refer to the MIB Reference manual.
VLANs
VLANs are created with standard Layer 2 Ethernet. A VLAN Identifier (VID) is associated with each
VLAN. VLANs offer the following benefits:
• VLANs are supported over all IEEE 802 LAN MAC protocols, and over shared media LANs as
well as point-to-point LANs.
• VLANs facilitate easy administration of logical groups of stations that can communicate as if
they were on the same LAN. They also facilitate easier administration of moves, adds, and
changes in members of these groups.
• Traffic between VLANs is restricted. Bridges forward unicast, multicast, and broadcast traffic
only on LAN segments that serve the VLAN to which the traffic belongs.
The VLAN field in the Ethernet file is located after both destination and source addresses:
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 (byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| Dest Addr | Src Addr | VLAN | Type/Length | ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
The VLAN field is separated as follows:
0 (bit) 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x8100 | Pri |T| VID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
For both signalling and media packets, the VLAN priority section is configurable independently.