How Does Qos Work; Qos Process For Ingress Traffic - Avaya P580 User Manual

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How Does QoS Work?

Document No. 650-100-700, Issue 1

The QoS process starts at the point where a frame enters the switch and ends

when the frame exits the switch. This section describes the QoS process

from start to finish.

The QoS process for ingress traffic involves the following steps:

1. Identifying the priority, also called class, of the frame or packet. The

switch can identify the priority of the frame or packet by using one or

more of the following criteria:

The priority of the physical port that the switch received the

frame or packet on

Cisco ISL tag priority

802.1p tag priority (default)

The source or destination MAC address

The DiffServ code point

The IP protocol (assigned by means of an ACL rule)

The source or destination IP address (assigned by means of an

The source or destination TCP or UDP port (assigned by means

of an ACL rule)

For more information on identifying the priority of traffic, see

"Classification of

Traffic" later in this chapter.

2. Storing the frame or packet in one of eight ingress queues.

The switch stores the frame or packet in the queue that matches the

priority that was identified in

3. Forwarding the frame or packet from the ingress queue to its destination.

If you enable policing for the queue, the switch forwards ingress traffic

that falls within the maximum bit rate that you set and drops ingress

traffic that exceeds the maximum bit rate. For more information on

policing, see

Policing" later in this chapter.

80-Series QoS