Quality Of Service Model - Allied Telesis SwitchBlade x3100 Series Manual

Introduction

6.2 Quality of Service Model

Packet-based networks provide primarily three types of services:
Data
•
Voice
•
Video
•
Providers must deliver these services at a level of quality acceptable to the customer. Service quality or service
level can be defined by controlling:
Availability
•
Delay
•
Delay variation (jitter)
•
Lost packet ratio (bandwidth)
•
Additionally, various applications (e-mail, file transfer, teleconferencing, video conferences) can be considered as
real-time verses non real-time applications.
Real-time applications (such as voice) have a lower tolerance to delay or delay variation, but can handle
•
some packet loss.
Non-real-time applications are not as adversely affected by delay or delay variation, but are highly affected
•
by packet loss.
A Service Level Agreement (SLA) details the level of service the service provider and customer negotiate. Pro-
viders use Quality of Service (QoS) functions to segregate traffic and then manage the service quality through
the network to meet the customer's needs.
Figure 6-1 shows the general flow for QoS; refer to this figure while reading the rest of this subsection.
The rest of this subsection describes in general what traffic management provides. For the capabilities
Note:
of the SBx3112 refer to the rest of this section. Refer to the next two sections for details (capabilities,
restrictions) on a specific product.
6-2
Software Reference for SwitchBlade x3100 Series Switches (Access and Security)