Quality of Service
Configuring QoS - General
Cisco 500 Series Stackable Managed Switch Administration Guide Release 1.3 490
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Rate limiting per VLAN, performed in the VLAN Ingress Rate Limit page,
enables
traffic limiting on VLANs. When VLAN ingress rate limiting is configured, it limits
aggregate traffic from all the ports on the device.
The following constraints apply to rate limiting per VLAN:
• It has lower precedence than any other traffic policing defined in the
system. For example, if a packet is subject to QoS rate limits but is also
subject to VLAN rate limiting, and the rate limits conflict, the QoS rate limits
take precedence.
• It is applied at the device level and within the device at the packet
processor level. If there is more than one packet processor on the device,
the configured VLAN rate limit value is applied to each of the packet
processors, independently. Devices with up to 24 ports have a single
packet processor, while devices of 48 ports or more have two packet
processors.
Rate limiting is calculated separately for each packet processor in a unit and for
each unit in a stack.
To define the VLAN ingress rate limit:
STEP 1 Click Quality of Service > General > VLAN Ingress Rate Limit.
This page displays the VLAN Ingress Rate Limit Table.
STEP 2 Click Add.
STEP 3 Enter the parameters.
• VLAN ID—Select a VLAN.
• Committed Information Rate (CIR)—Enter the average maximum amount
of data that can be accepted into the VLAN in Kilobytes per second.
• Committed Burst Size (CBS)—Enter the maximum burst size of data for the
egress interface in bytes of data. This amount can be sent even if it
temporarily increases the bandwidth beyond the allowed limit. Cannot be
entered for LAGs.
STEP 4 Click Apply. The VLAN rate limit is added, and the Running Configuration file is
updated.
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