Modify Port Settings Window

This window appears when you:

To modify port settings:

  1. In the Description field, enter a description for the selected port.
    Your description should help you identify the ports. For example, end stations might be a useful description. If you limit the length of your description to 13 characters or less, the entire description will fit in this field without scrolling.
  2. Select the remaining parameter settings from the drop-down lists.
    See Settings Table and Setting IEEE 802.1P Priority Tags for information on parameter settings if you need help.
  3. Click OK to put your changes in effect and close the window.
    Your new settings appear in the Port Settings window.

If you select multiple ports and specify a configuration setting that is not valid for a selected port, the current setting remains unchanged. For example, if you select a 10BASE-T Ethernet, a Fast Ethernet, and a Gigabit port and then select a speed of 100 Mbps, the 10BASE-T Ethernet port will remain set to 10 Mbps and the Gigabit port will remain set to 1000 Mbps.

Note: Catalyst 2912-XL, 2924-XL, and 2924C-XL switches do not support Gigabit Ethernet ports.

Settings Table

Note: You can configure and monitor the Ethernet link on a Cisco 575 LRE CPE. However, you cannot configure the Ethernet links on a Cisco 585 LRE CPE. You can only monitor the Ethernet links on the Cisco 585 LRE CPE by using the show remote interfaces status user EXEC command.

SettingsExplanation
Description Text description of the port. (If you selected more than one port, this field is disabled. Click Describe in the Port Settings window to describe multiple ports.)
Status Setting to enable or disable the port, which can be different from the runtime setting. For example, if no device is connected to a port, it can be administratively enabled with a runtime status of DOWN.
Note: When you disable a port, a linkdown trap is sent to the management station if you configured an SNMP manager.
Duplex

Setting for duplex: full duplex, half duplex, or autosensing. The default setting for Gigabit Ethernet and GigaStack GBIC ports is auto. These ports automatically match the duplex capability of an attached device.

GigaStack GBIC stack connections operate in half-duplex mode.

Point-to-point GigaStack GBIC port connections operate in full-duplex mode.

Gigabit Ethernet ports can automatically match the duplex capability of an attached device.

ATM ports do not autonegotiate duplex or speed settings.

Note: On a Long-Reach Ethernet (LRE) port, this is the duplex mode setting of the Ethernet port on a Cisco 575 LRE CPE. The default setting is half duplex. For more descriptions and considerations about configuring the LRE ports, see LRE Port Considerations.

Speed

Setting for Fast Ethernet ports: 10 (10 Mbps), 100 (100 Mbps), or auto (autonegotiating). Fast Ethernet ports can automatically match the transmission speed of an attached device. The default setting for Fast Ethernet ports is auto.

Note: On a LRE port, this is the speed setting of the Ethernet port on a Cisco 575 LRE CPE. The default setting is auto. This setting does not reflect the upstream and downstream LRE link speeds, which are defined by the active LRE profile assigned to the LRE port and are displayed from the Configuration Settings tab. For more descriptions and considerations about configuring the LRE ports, see LRE Port Considerations.

Port Fast

Immediately brings a port from the blocking state into the forwarding state by eliminating the forwarding delay (the amount of time a port waits before changing from its STP learning and listening states to the forwarding state). You can choose to enable it for static-access ports only or for static-access and trunk ports.

Note: For Catalyst 2950 and 3550 switches, this column will show NA if no STP information is available for the interface. In this state, you cannot modify Port Fast on the interface.

802.1P PriorityAssigns a priority to traffic containing an 802.1P or ISL user priority tag.
Note: Catalyst 2950 switches do not support ISL user priority tags.
To direct this traffic to a high-priority queue, assign a value of 4 through 7. To direct this traffic to a normal queue, assign a value of 0 through 3. The switch forwards normal traffic only after it forwards all high-priority traffic. On Catalyst 2900 XL and 3500 XL switch ports, these settings also apply to untagged (native Ethernet) traffic.
Flow Control

On Gigabit Ethernet ports, enables or disables flow control, which manages traffic rates during congestion. If a port is congested and cannot receive more traffic, flow control notifies the other port to stop transmitting until the condition clears. This list appears only if Gigabit Ethernet ports are present. It does not apply to Fast Ethernet or ATM ports, and it is not enabled for Catalyst 3550 switches.

By default, when the GigaStack GBIC is in a stack configuration (cascade), flow control is disabled. When the GigaStack GBIC is in a point-to-point configuration, flow control is set to asymmetric, the same setting for GBICs in general.

Select None to disable flow control on the port.
Select Symmetric to have the local port perform flow control on the remote port. This option works only if the remote port can also perform flow control on the local port.
Select Asymmetric to have the local port perform flow control on the remote port. For example, if the local port is congested, it notifies the remote port to stop transmitting. This setting is the default.
Select Any when the local port can support any level of flow control required by the remote port.

Note: The flow-control setting on the CPE Ethernet port is automatically disabled in half-duplex mode and automatically enabled in full-duplex mode. You cannot configure the flow-control setting on the CPE Ethernet ports. For more descriptions and considerations about configuring the LRE ports, see LRE Port Considerations.

Setting IEEE 802.1Q Priority Tags

You can configure quality of service (QoS) for traffic containing IEEE 802.1Q or ISL user priority tags. When the switch receives tagged traffic, it transfers the traffic to two queues: a normal queue receives frames with priority values from 0 to 3, and a high-priority queue receives frames with priority values from 4 to 7. Traffic on the normal queue is forwarded only after traffic on the high-priority queue is forwarded.

Catalyst 2900 XL and 3500 XL switches can also provide QoS on untagged (native Ethernet) traffic, based on a priority level that you assign to the ingress port (the receiver queue buffer for incoming traffic). If you assign a port priority level from 0 to 3, traffic is forwarded to the normal-priority queue of the output port. If you assign a priority level from 4 to 7, traffic is forwarded to the high-priority queue of the output port. When 802.1P or ISL tagged traffic passes through the trunk port, it retains the 802.1P or ISL tag.

Catalyst 1900 and 2820 switches, Catalyst 2924 and 2924C XL switches with only 4 MB of memory, and switches running IOS Release 11.2 (8)SA6 or earlier do not support priority levels.

Note: If you are connecting to a switch in the Catalyst 6000 family, the switch must be configured for compatibility with 2900 and 3500 XL switches. Refer to your Catalyst 6000 documentation for information on making the necessary changes.