Configuring Flow Control Policies

Flow Control Policy

Flowcontrol policies determine whether the uplink Ethernet ports in a Cisco UCS domain send and receive
IEEE802.3x pauseframes when the receivebuffer for a port fills. These pause frames request that the
transmittingport stop sendingdata fora fewmilliseconds until thebuffer clears.
Forflow control to work between a LAN port and an uplink Ethernet port, you must enable the corresponding
receiveand send flow controlparameters for both ports. For Cisco UCS, the flow control policies configure
theseparameters.
Whenyou enable the send function, the uplink Ethernet port sends a pause request to the network port if the
incomingpacket rate becomes too high. The pause remains in effect for a few milliseconds before traffic is
resetto normal levels. If you enable the receive function, the uplink Ethernet port honors all pause requests
fromthe network port. All traffic is halted on that uplink port until the network port cancels the pause request.
Becauseyou assign the flow control policy to the port, changes to the policy have an immediate effect on how
theport reacts to a pause frame or a full receive buffer.

Creating a Flow Control Policy

Before You Begin
Configurethe network port with the corresponding setting for the flow control that you need. For example,
ifyou enable the send setting for flow-control pause frames in the policy, make sure that the receive parameter
inthe network port is set to on or desired. If you want the Cisco UCS port to receive flow-control frames,
makesure 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 receiveparameters on the network port to off.
Procedure
Step 1 Inthe Navigation pane, clickthe LAN tab.
Step 2 Onthe LAN tab, expand LAN >Policies.
Step 3 Expandthe root node.
Youcan only create a flow control policy in the root organization. You cannot create a flow control policy
ina sub-organization.
Step 4 Right-clickthe Flow ControlPolicies node and select Create Flow Control Policy.
Step 5 Inthe Create Flow Control Policy wizard, complete the following fields:
DescriptionName
Thename of thepolicy.
Thisname can be between 1 and 16 alphanumeric characters. You
cannotuse spaces or any special characters other than - (hyphen), _
(underscore),: (colon), and . (period), and you cannot change this name
afterthe object has beensaved.
Namefield
Cisco UCS Manager GUI Configuration Guide, Release 2.0
304 OL-25712-04
Configuring Flow Control Policies