Avaya Cajun P580, User Manual, Page: 663 / 770

Document No. 650-100-700, Issue 1 25-3
80-Series QoS
How Does QoS Work?
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.
QoS Process for Ingress Traffic
Process
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
ACL rule)
—
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
Step 1 .
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 “
Ingress Policing ” later in this chapter.