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36 Using Enterprise Edge Services

Enterprise Edge Networking Operations Guide P0910464 Issue 01

Relationship between the QoS Module and the VoIP QoS Monitor

The VoIP gateway in Enterprise Edge includes a Quality-of-Service Monitor

(QMON) that periodically monitors the delay and jitter of IP networks between two

peer gateways by using a proprietary protocol. These monitoring packets are

delivered at UDP port 5000.

The main objective of the QMON is to allow new VoIP calls to fall-back to PSTN

if the IP network is detected as “bad”.

The QoS module discussed here complements QMON. While QMON passively

monitors the IP network, the QoS module actively improves the IP network by

giving VoIP packets higher priority to travel so that the chance for QMON to detect

“bad” is reduced.

Note: For a VoIP call, if a packet passes QMON but fails the QoS admission

control, it is delivered over IP but only as a best-effort flow. There is no fall

back to PSTN if a packet has passes QMON checking.

QMON packets travel at the same priority as VoIP packets or at higher priority than

normal IP packets. If VoIP packets travel at a premium level but QMON packets

travel at normal best-effort level, it is possible for QMON to report the IP network

as “bad” and start to PSTN fall-back, but the actual delay and jitter for VoIP packets

are still “good”, since VoIP packets have a higher priority. To avoid this add UDP

port 5000 to the high priority queue in all routers.

Enterprise Edge QoS Restrictions and Defaults

Enterprise Edge QoS includes the following restrictions and defaults:

• By default, the general bulk of traffic (not defined by priority filters) is routed

to best-effort Queue 5 (with Queue 1 the highest priority and Queue 8 the

lowest). An administrator can define four classes of traffic above the generic

traffic and three classes below it.

• A maximum of 31 priority filters for best-effort traffic can be created.

• The QoS module can be optionally turned ON or OFF. The default setting is on.

• The predetermined WAN bandwidth is always available to VoIP gateway

channels. That is, VoIP gateway calls are always admitted. The remaining

WAN premium bandwidth can be used by other H.323 streams, such as

Microsoft NetMeeting. If there is no VoIP gateway traffic, their WAN

bandwidth can be used only by best-effort traffic, not other premium traffic (for

example, Netmeeting). Enterprise Edge does not support preemption of

admitted premium streams.

• Currently packet prioritizing and priority filters apply only to outbound traffic

for specified interfaces. Inbound traffic is treated on a first in first out (FIFO)

priority.

• The maximum port numbers a user can reserve for premium traffic is 256.

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Avaya EE Networking Podręcznik Użytkownika Strona 36