Configuring Quality Of Service - Alcatel OS-LS-6224 User Manual

Service provider packets sent to the subscriber arrive from the following VLAN
types:
• Subscriber VLANs
• Multicast TV VLANs
Each subscriber on a network maintains a Customer Premise Equipment
Multi-Connect (CPE MUX) box. The MUX boxes directs network traffic from uplink
ports to MUX access ports. MUX access ports are based on VLAN tags located in
packet headers. Service provider's packets are tagged twice. Each packet has an
internal tag and an external tag. The external tag indicates if the packet arrived from
a Multicast TV VLAN or from a subscriber's VLAN. The internal tag indicates the port
within the VLAN to which the packet is addressed.
The VLAN tag identifies:
• The media service type, including:
• Internet
• TV
• Phone
• The service provider.

Configuring Quality of Service

Network traffic is usually unpredictable, and the only basic assurance that can be
offered is best effort traffic delivery. To overcome this challenge, Quality of Service
(QoS) is applied throughout the network. This ensures that network traffic is
prioritized according to specified criteria, and that specific traffic receives preferential
treatment. QoS in the network optimizes network performance and entails two basic
facilities:
• Classifying incoming traffic into handling classes, based on an attribute, including:
• The ingress interface
• Packet content
• A combination of these attributes
• Providing various mechanisms for determining the allocation of network resources
to different handling classes, including:
• The assignment of network traffic to a particular hardware queue
• The assignment of internal resources
• Traffic shaping
In this document, the terms Class of Service (CoS) and QoS are used in the
following context:
• CoS provides varying Layer 2 traffic services. CoS refers to classification of traffic
to traffic-classes, which are handled as an aggregate whole, with no per-flow
settings. CoS is usually related to the 802.1p service that classifies flows according
to their Layer 2 priority, as set in the VLAN header.
Configuring Quality of Service
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