This tab lets you view and configure the components of a class of service (CoS). See below for a description of each section. For more information, see How to Create a Class of Service.
Once you have created and defined a class of service, you can then apply it as a classification rule action, as part of the definition of an automated service, or as a role default. For more information, see Getting Started with Class of Service.
To access this tab, open the Class of Service Configuration window (available from the Policy Manager Edit menu). Then, select the "Show all CoS Components in Tree (Advanced Mode)" option from the Domain Managed CoS Components menu to display the CoS tree in the left panel. Select a class of service in the tree, and the General tab will display in the right panel.
| NOTE: | The actual columns that appear under Rate Limiting/Rate Shaping tab might vary based on the Port Details View and SNMP options settings on the Policy Manager Options Window. |
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Click the graphic for more information.
General
- Description
- Use the Edit button to open a window where you can add or modify a description for the class of service.
- Transmit Queue
- This field displays the transmit queue associated with the class of service for each port type. Use the Edit button to display a menu where you can select a new transmit queue, if desired.
- 802.1p Priority
- The 802.1p priority associated with the class of service, if any. The checkbox lets you enable or disable the priority, and the drop-down list lets you choose a different 802.1p priority, if desired. If the 802.1p priority is associated with a particular inbound and/or outbound priority-based rate limit, that rate limit information will be displayed to the right. This field will be grayed out for the eight static classes of service provided by Policy Manager (Priority 0-7), because the 802.1p priority cannot be disabled or changed.
- ToS/DSCP Marking
- Some IP rules allow a ToS/DSCP value to be
written to the ToS/DSCP field in the IP header of incoming packets.
This checkbox lets you enable or disable the IP ToS (Type of
Service) or DSCP (Diffserv Codepoint) rewrite value associated with this class of service. See ToS/DSCP Rewrite and ToS/DSCP Value Definition Chart
for more information.
- Value - The IP type of service value is an 8-bit hexadecimal number between 0 and FF (see IP Type of Service for more information). You can either enter this value in the 0x text box, or click Select to open the ToS/DSCP Configuration window, where you can automatically configure a ToS (Type of Service) or DSCP (Diffserv Codepoint) value.
- Mask - The ToS mask controls which bits in the ToS/DSCP field of incoming packets will be overwritten.
- Drop Precedence
- The Drop Precedence option is used in conjunction with the Flex-Edge feature available on K-Series and S-Series (Release 7.11 or higher) devices. Flex-Edge provides the unique capability to prioritize traffic in the MAC chip as it enters the switch. When the Class of Service is assigned to a policy role, and that role is applied to a port via a MAC source address mapping or the port default role, the drop precedence will dictate the internal priority (within the MAC chip) that will be used for packets received on the port. If congestion occurs, packets with a high drop precedence are discarded first. Therefore, if a packet is important, it should have a low drop precedence. Refer to the K-Series or S-Series Configuration Guide for more information on the Flex-Edge feature and drop precedence.
Rate Limiting/Rate Shaping
This section displays the inbound/outbound rate limits (IRL/ORL) and the outbound transmit queue (TxQ) rate shapers that are configured for the Default port groups associated with the class of service. If you have created additional port groups, the information will be displayed for those groups as well.
With port rate limits, all traffic assigned to this class of service on a given port will share bandwidth specified by the rate limit. Rate shaping paces the rate at which traffic is transmitted out of the transmit queue. You can add or change a rate limit or a rate shaper by double-clicking on the area below a port group name.
If you have ExtremeWireless Wireless Controllers (Release 8.01.xx or higher) on your network, you will also see the IRL and ORL user rate limits associated with the class of service. User rate limits specify the bandwidth given to each individual user on a port. Currently, user rate limits are only available on wireless controllers.
For more information, see Advanced Rate Limiting by Port Type and How to Configure Transmit Queues.
Index Numbers
At the bottom of the tab there is a section for configuring the rate limit and transmit queue index numbers associated with this class of service. These index numbers are used to map the class of service to the actual rate limits and transmit queue configuration on the device.
Typically, each class of service uses a different index number. Policy Manager automatically assigns these index numbers when you configure a class of services's rate limits and transmit queue shapers. An index number of "-1" indicates that no mappings are associated with the class of service.
All CoS using the same index will use the same rate limit and rate shaping assignments, and thus all traffic using those CoS will share the bandwidth.
- IRL/ORL Index (Inbound/Outbound Rate Limits Index)
- The inbound/outbound port rate limit index associated with the class of service. Index numbers map logical rate limit indexes to the actual physical rate limits you have created in Policy Manager. Click the button to open the Rate Limits selection view window, and select an index for the CoS. For convenience, existing index to rate limit mappings are displayed; if one of the existing indexes is selected, the displayed mappings will apply for this CoS. (Selecting an index highlights all the mappings configured for that index number within the selection view.)
- TxQ Index (Transmit Queue Index)
- The transmit queue index associated with the class of service. Index numbers map logical transmit queue indexes on the ports to the actual physical transmit queues you have configured in Policy Manager. If you have selected an 802.1p priority for this class of service, a default transmit queue index is automatically specified based on the selected priority. You can use the default index or change it according to your own transmit queue configuration. Click the button to open the Transmit Queues selection view window, which lists all the possible transmit queues, organized by index number for each existing port type and group. Selecting an index automatically includes all the transmit queues configured for that index number.
- IUB/OUB Index (Inbound/Outbound User-Based Rates Index)
- If you have ExtremeWireless Wireless Controllers (Release 8.01.xx or higher) on your network, you will also see the inbound/outbound user rate limits associated with the class of service. User rate limits specify the bandwidth given to each individual user on a port. Currently, user rate limits are only available for these wireless controllers. Click the button to open the Rate Limits selection view window, and select an index for the CoS. For convenience, existing index to rate limit mappings are displayed; if one of the existing indexes is selected, the displayed mappings will apply for this CoS. (Selecting an index highlights all the mappings configured for that index number within the selection view.)
- Flood Ctrl Port Groups
- CoS-based flood control is a form of rate limiting that prevents configured ports from being disrupted by a traffic storm, by rate limiting specific types of packets through those ports. When flood control is enabled on a port, incoming traffic is monitored over one second intervals. During an interval, the incoming traffic rate for each configured traffic type (unknown-unicast, broadcast, or multicast) is compared with the configured traffic flood control rate, specified in packets per second. If, during a one second interval, the incoming traffic of a configured type reaches the traffic flood control rate configured on the port, CoS-based flood control drops the traffic until the interval ends. Packets are then allowed to flow again until the limit is again reached.
| NOTE: |
By default, Flood Control is not managed by Policy Manager. To manage flood control configuration on devices in a domain, it can be enabled via the Domain Managed CoS Components drop-down menu by selecting All CoS Components or by selecting Flood Control. |
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