Riverbed SteelHead 3070-SD, User Manual

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Configuring QoS Shaping on SteelHead SD | 105
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Configuring QoS Shaping on SteelHead SD
This topic describes how to configure QoS shaping. It includes these sections:
• “QoS shaping on SteelHead SD” on page 105
• “If you set the QoS priority in a traffic rule” on page 106
• “Configuring QoS shaping on SteelHead SD” on page 107
These procedures describe QoS shaping for SteelHead SD 570-SD, 770-SD, and 3070-SD appliances
and the SteelConnect SDI-2030 gateway located at the branch.
QoS shaping on SteelHead SD
SteelHead SD supports QoS shaping to allocate bandwidth and prioritize traffic. With SteelHead SD QoS
there are no classes to configure: you simply set the bandwidth with a fixed value to provide QoS shaping
on inbound and outbound traffic. QoS shaping is supported on site uplinks of a given WAN.
You configure QoS as a policy on a WAN uplink to ensure that your uplink doesn’t exceed a set
bandwidth. For example, if you know your uplink can’t handle more than 100 Mbps, you set your limit at
something lower than 100 Mbps to ensure that you have a minimal level of service for that uplink. If traffic
exceeds the configured bandwidth, it is buffered and shaped. If traffic exceeds the buffer capacity, it is
dropped. The QoS shaper throttles and limits traffic to your configured bandwidth.
QoS prioritizes traffic flowing on:
• Outbound QoS - Outbound QoS prioritizes and shapes outbound traffic on a WAN uplink. Egress
traffic on a WAN uplink is provisioned with an outbound QoS policy.
• Inbound QoS - Inbound QoS prioritizes and shapes inbound traffic on a WAN uplink, ingress traffic
on a WAN uplink is provisioned with an inbound QoS policy.
Note: QoS marking is currently supported on SteelConnect when you define a traffic rule to match on a specified
site or application to apply an outbound DSCP mark. For additional information on QoS marking, see the
SteelConnect Manager User Guide .
SteelHead SD QoS shaper
SteelHead SD QoS uses a class-based queuing implementation that assigns packets with a DSCP mark
to one of the four dedicated service class queues and distributes bandwidth between them using a deficit
weighted round robin (DWRR) scheme. Traffic scheduling and shaping uses a basic single rate and
bucket algorithm to regulate the data transmission rate and drain the queues. QoS shaping: