DAG2000 Series FXS Voice Gateway User Manual
17
Dinstar Technologies Co., Ltd.
4.5.2 VLAN Parameter
Generally, Internet provides only Best Effort Service. Since Ethernet is the most spread LAN
access technology, importance of providing it a quality of service mechanism ought not to
be neglected.
Ethernet technology also used as WAN technology, not only as LAN technology. Due to
rapidly increasing use Internet through Public Switched Telecommunication Network
(PSTN), Telephone Companies are forced to implement IP-based networks as their PSTN
backbones. A network like this without any Quality of Service mechanisms would be
disastrous. Just imagine yourself trying to get an emergency call through while others just
surf the Internet.
1) 802.1Q
The IEEE 802.1Q standard defines architecture for Virtual Bridged LANs, the services
provided in Virtual Bridged LANs and the protocols and algorithms involved in the provision
of those services.
No Quality of Service mechanisms are defined in this standard, but an important
requirement for providing QoS is included in this standard, e.g. ability to regenerate user
priority of received frames using priority information contained in the frame and the User
Priority Regeneration Table for the reception Port.
2) 802.1p
IEEE 802.1p standard, Traffic class expediting and dynamic multicast filtering. It describes
important methods for providing QoS at MAC level. IEEE 802.1p is in fact quite good.
Lower priority level packets are not sent, if there is packet in queued in higher level queues.
IEEE 802.1p describes no admission control protocols. It would be possible to give Network
Control priority to all packets and the network would be easily congested.
There are three VLAN: data VLAN, voice LAN and management VLAN. VLAN configuration
interface as following figure 4-4-3:
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