Specifications

SecureStack A2 Configuration Guide 8-1
8
Port Priority and Rate Limiting
Configuration
This chapter describes the Port Priority and Rate Limiting set of commands and how to use them.
8.1 PORT PRIORITY CONFIGURATION SUMMARY
The SecureStack A2 device supports Class of Service (CoS), which allows you to assign
mission-critical data to higher priority through the device by delaying less critical traffic during
periods of congestion. The higher priority traffic through the device is serviced first before lower
priority traffic. The Class of Service capability of the device is implemented by a priority queueing
mechanism. Class of Service is based on the IEEE 802.1D (802.1p) standard specification, and
allows you to define eight priorities (0 through 7) and assign them to the transmit queues for each
port.
A priority 0 through 7 can be set on each port, with 0 being the lowest priority. A port receiving a
frame without priority information in its tag header is assigned a priority according to the default
priority setting on the port. For example, if the priority of a port is set to 4, the frames received
through that port without a priority indicated in their tag header are classified as a priority 4 and
transmitted according to that priority.
The device’s rate limiting capabilities allow you to prioritize traffic by limiting the rate of inbound
traffic on a per port/priority basis.
8.2 PROCESS OVERVIEW: PORT PRIORITY AND RATE LIMITING
Use the following steps as a guide to the port priority, QoS classification, and rate limiting
configuration process:
1. Configuring Port Priority (Section 8.3.1)
2. Configuring Priority Queueing (Section 8.3.2)