Objective:

Bandwidth refers to the average amount of data successfully transferred through a communication path. Bandwidth shaping, management, capping and setting allocation are some of the techniques used to improve bandwidth utilization. You may change the bandwidth for both incoming and outgoing traffic. It may be necessary to limit bandwidth on specific ports in order to prevent a small number of ports from taking up a large portion of the switch’s bandwidth.

The objective of this document is to show you how to limit bandwidth on individual ports on the SG500 series.

Applicable Devices:

• Cisco Small Business 500 series Managed Switches

Software Versions:

• 1.3.7.18

Setting the Absolute Time Range

Step 1. Log in to the web configuration utility and choose Quality of Service > General > Bandwidth. The Bandwidth page opens:

The Bandwidth Table displays the following fields:

• Ingress Rate Limit – Maximum amount of bandwidth dedicated for incoming ports.

– Status – Displays if the Ingress Rate Limit is enabled for the port.

– Rate Limit – Displays the max bandwidth (in Kbits/sec) for the port.

– % - Displays the portion of the total bandwidth allocated for the port.

– CBS (Bytes) – Displays the Committed Burst Size (CBS) or the maximum burst size that can be sent in a given time.

• Egress Shaping Rate - Maximum amount of bandwidth dedicated for outgoing ports.

– Status – Displays if the Egress Shaping Rate is enabled for the port.

– CIR - (Kbits/sec) – Committed Information Rate (CIR) displays the max bandwidth (in Kbits/sec) for the port.

– CBS (Bytes) – Displays the Committed Burst Size (CBS) or the maximum burst size that can be sent in a given time.

Step 2. Click the radio button of the desired port you wish to configure.

Step 3. Click Edit.

The Edit Bandwidth page opens:

Step 4. (Optional) Next to the Ingress Rate Limit check Enable if you wish to edit the rate of incoming traffic. If not, skip to step 7.

Step 5. Enter the desired limit in KBits/sec (Kbps) in the Ingress Rate Limit field. The default limit is 100 KBits/sec.

Step 6. Enter the desired burst size in bytes in the Ingress Committed Burst Size (CBS) field. A CBS allows a group of packets up to a certain size to be sent over the network regardless of the current ingress rate limit. Setting a CBS too low can result in a large amount of small packets constantly being sent over the network. This leads to one port consistently having a large amount of traffic. Setting a burst rate too high will allow too many large groups of packets to be sent over the network. This can result in one port taking up a larger portion of their allocated bandwidth too frequently. The optimal rate will result in no wasted bandwidth. The default size is 128000 Bytes.

Step 7. (Optional) Next to the Egress Shaping Rate check Enable if you wish to edit the rate of outgoing traffic. If not, skip to step 10.

Step 8. Enter the desired limit in KBits/sec (Kbps) in the Committed Information Rate (CIR) field. A CIR is the minimum bandwidth guaranteed for your network. Setting a CIR for a port will guarantee that the port will always get a minimum bandwidth for the specified port. Setting a rate too low can cause quality issues when streaming audio or video over a network. Setting a rate too high can give one port more support than it needs, resulting in inefficiencies in your network. The optimal rate will result in no wasted bandwidth. The default limit is 64 KBits/sec.

Step 9. Enter the desired burst size in bytes in the Egress Committed Burst Size (CBS) field. For more information on Committed Burst Sizes, refer to Step 6. The default size is 128000 bytes.

Step 10. Click Apply to save the settings.

Step 11. In order to save your settings, click Copy/Save Configuration.

The following alert appears:

Step 12. Click OK.

Step 13. Click Apply to save your current running configuration to the startup configuration.