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QUALITY
OF
SERVICE (QOS)
INTRA-SUBNET QOS
Intra-Subnet QoS™ (ISQ) allows the application of any IPQoS commands to be effective
within a subnet (VLAN) instead of only applying the QoS when traversing a routed
subnet. The command syntax for all IPQoS commands remains the same; ISQ is simply
enabled on a per VLAN basis.
Because ISQ instructs the switch to look at IP addresses within a VLAN, the normal
MAC-based learning and refreshing for layer 2 switching is altered for traffic that
matches an IPQoS traffic grouping. Instead, learning and refreshing is done based on IP
information in the packets. As a result, it is necessary to increase the FDB aging timer
comfortably above a normal ARP table refresh time to 50 minutes (3,000 seconds). This
occurs automatically when ISQ is enabled. ISQ should not be used on VLANs with
clients that have statically defined ARP tables. To verify the FDB timer, use the
following command:
show fdb
The aging time is displayed at the end of the table.
MAC-BASED TRAFFIC GROUPINGS
QoS profiles can be assigned to destination MAC addresses. The various options that
fall into this category are as follows:
• Permanent
• Dynamic
• Blackhole
• Broadcast/unknown rate limiting
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EXTREMEWARE SOFTWARE USER GUIDE