Quality of Service
The Quality of Service feature is useful when some of the traffic handled by the gateway has
higher importance than other data being handled at the same time. For example, you might
set up your computer to make telephone calls over the Internet. If you have a voice
conversation while your computer is also downloading a file, you would want the voice
conversation to take precedence over the file download, since delays in transmitting voice
messages would cause signal dropouts and poor sound quality.
How QoS works
The QoS feature would help you if all of the following conditions are met:
The PVC is not in bridge mode (that is, the WAN protocol can be in
PPPoA
,
PPPoE
,
IPoA
or
MER
)
The PVC is set to one of the following ATM service categories:
UBR-with-PCR
UBR-without-PCR
Non-realtime-VBR
There are enough ATM TX queues left in the system.
QoS classifies traffic according to classification rules you define. Each rule may contain a
combination of the following conditions: protocol (TCP/UDP/ICMP), source IP address/subnet
mask, destination IP address/subnet mask, source port (one or range), destination port (one
or range). Any session that matches a classification rule receives a certain priority (high,
medium, low) and a type of service (normal service, minimum cost, maximum reliability,
maximum throughput, or minimum delay).
The priority of the matching rule determines which ATM TX queue to send over the PVC if the
packet is routed to this PVC. ATM picks packets to process according to these priorities:
1. ATM service categorizes from the highest to lowest order: CBR, rt-VBR, rrt-VBR, UBR.
2. For the same service category: Priority level from high, medium, to low.
3. For the same priority level: round robin.
QoS only works for QoS-enabled PVCs. If data is routed to a regular QoS-disabled PVC, it will
receive the same priority level as the low priority of a QoS-enabled PVC in the same ATM
service category.
Enabling QoS
To enable the QoS feature, follow this procedure:
1. Go to the
Internet
menu and select
WAN Setup
.
2. From there, click either
Add
or
Edit
.
3. In the resulting page, click
Enable Quality of Service
.
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U.S. Robotics Wireless MAXg ADSL Gateway User Guide
2005/7/4
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