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Configuring Flow Control Policies
Flow Control Policy
Flow control policies determine whether the uplink Ethernet ports in a Cisco UCS domain send and receive
IEEE 802.3x pause frames when the receive buffer for a port fills. These pause frames request that the
transmitting port stop sending data for a few milliseconds until the buffer clears.
For flow control to work between a LAN port and an uplink Ethernet port, you must enable the corresponding
receive and send flow control parameters for both ports. For Cisco UCS, the flow control policies configure
these parameters.
When you enable the send function, the uplink Ethernet port sends a pause request to the network port if the
incoming packet rate becomes too high. The pause remains in effect for a few milliseconds before traffic is
reset to normal levels. If you enable the receive function, the uplink Ethernet port honors all pause requests
from the network port. All traffic is halted on that uplink port until the network port cancels the pause request.
Because you assign the flow control policy to the port, changes to the policy have an immediate effect on how
the port reacts to a pause frame or a full receive buffer.
Creating a Flow Control Policy
Before You Begin
Configure the network port with the corresponding setting for the flow control that you need. For example,
if you enable the send setting for flow-control pause frames in the policy, make sure that the receive parameter
in the network port is set to on or desired. If you want the Cisco UCS port to receive flow-control frames,
make sure that the network port has a send parameter set to on or desired. If you do not want to use flow
control, you can set the send and receive parameters on the network port to off.
Procedure
Step 1
In the Navigation pane, click the LAN tab.
Step 2
On the LAN tab, expand LAN > Policies.
Step 3
Expand the root node.
You can only create a flow control policy in the root organization. You cannot create a flow control policy
in a sub-organization.
Step 4
Right-click the Flow Control Policies node and select Create Flow Control Policy.
Step 5
In the Create Flow Control Policy wizard, complete the following fields:
DescriptionName
The name of the policy.
This name can be between 1 and 16 alphanumeric characters. You
cannot use spaces or any special characters other than - (hyphen), _
(underscore), : (colon), and . (period), and you cannot change this name
after the object has been saved.
Name field
Cisco UCS Manager GUI Configuration Guide, Release 2.0
304 OL-25712-04
Configuring Flow Control Policies