Qos Process For Egress Traffic - Avaya 580 User Manual

Chapter 25
Example

QoS Process for Egress Traffic

Process
25-4
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
You want to assign a priority of 5 to a VoIP flow that is destined to an IP
600 phone switch. You also want to police the port that receives the VoIP
data to 5 Mbps.
1. You set up an ACL rule that associates a priority of 5 with the destination
IP address of the VoIP flow. (VoIP traffic cannot tolerate latency or
frame loss, so it needs a high priority to ensure its timely delivery.)
*Note: Priority 5 serves as an example only. Actual
implementations may vary.
2. You enable policing on the port that will receive the VoIP flow and set
the guaranteed bit rate to 5 Mbps.
3. The switch stores packets that match the ACL rule in queue 5. (The
switch stores packets in the queue that matches their priority.)
4. The switch forwards the VoIP traffic in queue 5 as long as its bit rate
does not exceed 5 Mbps. If the bit rate of the queue exceeds 5 Mbps, the
switch drops the excess traffic.
The QoS process for egress traffic involves the following steps:
1. Storing the frame or packet in one of eight egress queues.
The switch stores the frame or packet in the queue that matches the
priority that was identified on the ingress port.
2. Forwarding the frame or packet from the queue to the egress port for
transmission.
The switch uses algorithms that allocate bandwidth among the egress
queues to forward the traffic in the queues. The Avaya Multiservice
switch software supports the following queue-servicing algorithms for
egress ports:
Weighted fair queuing (WFQ)
—
Class-based queuing (CBQ)
—
Class-based weighted fair queuing (CBWFQ)
—
Strict Priority Queuing
—
User Guide for the Avaya P580 and P882 Multiservice Switches, v6.1
Policing" later in this chapter.