Media5 Mediatrix 4104, Справочное руководство, Страница: 137 / 466

Mediatrix 4104 115
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Web Interface – Advanced
The Advanced page allows you to configure various system and network parameters of the Mediatrix 4104.
Quality of Service (QoS)
QoS (Quality of Service) features enable network managers to decide on packet priority queuing. The
Mediatrix 4104 supports the Differentiated Services (DS) field and 802.1q taggings. The Mediatrix 4104
supports the Real Time Control Protocol (RTCP), which is used to send packets to convey feedback on quality
of data delivery.
The Mediatrix 4104 does not support RSVP (Resource Reservation Protocol).
802.1q Configuration
The 802.1q standard recommends the use of the 802.1q VLAN tags for Ethernet frames traffic prioritization.
VLAN tags are 4-byte headers in which three bits are reserved for priority indication. The values of the priority
bits shall be provisioned.
The 802.1q standard comprises the 802.1p standard.
You can also set these parameters via SNMP, as described in “Chapter 27 - Quality of Service (QoS)” on
page 335 .
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.