Ieee 802.3X Flow Control; Layer 3 Interfaces - Cisco Catalyst 2960-XR Configuration Manual

Configuring Interface Characteristics
• When STP is enabled and a port is reconfigured, the switch can take up to 30 seconds to check for loops.
Changing the interface speed and duplex mode configuration might shut down and re-enable the interface
Caution
during the reconfiguration.

IEEE 802.3x Flow Control

Flow control enables connected Ethernet ports to control traffic rates during congestion by allowing congested
nodes to pause link operation at the other end. If one port experiences congestion and cannot receive any more
traffic, it notifies the other port by sending a pause frame to stop sending until the condition clears. Upon
receipt of a pause frame, the sending device stops sending any data packets, which prevents any loss of data
packets during the congestion period.
The switch ports can receive, but not send, pause frames.
Note
You use the flowcontrol interface configuration command to set the interface's ability to receive pause frames
to on, off, or desired. The default state is off.
When set to desired, an interface can operate with an attached device that is required to send flow-control
packets or with an attached device that is not required to but can send flow-control packets.
These rules apply to flow control settings on the device:
• receive on (or desired): The port cannot send pause frames but can operate with an attached device that
• receive off: Flow control does not operate in either direction. In case of congestion, no indication is
For details on the command settings and the resulting flow control resolution on local and remote ports,
Note
see the flowcontrol interface configuration command in the command reference for this release.

Layer 3 Interfaces

The switch supports these types of Layer 3 interfaces:
• SVIs: You should configure SVIs for any VLANs for which you want to route traffic. SVIs are created
OL-29420-01
The port LED is amber while STP reconfigures.
is required to or can send pause frames; the port can receive pause frames.
given to the link partner, and no pause frames are sent or received by either device.
when you enter a VLAN ID following the interface vlan global configuration command. To delete an
SVI, use the no interface vlan global configuration command. You cannot delete interface VLAN 1.
Catalyst 2960-XR Switch Interface and Hardware Component Configuration Guide, Cisco IOS Release 15.0(2)EX1
IEEE 802.3x Flow Control
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