Users Guide

Disabling DCB To congure the Aggregator so that all interfaces are DCB disabled and ow control enabled, use the no dcb
enable command.
dcb enable auto-detect on-next-reload Command Example
Dell#dcb enable auto-detect on-next-reload
Conguring Priority-Based Flow Control
PFC provides a ow control mechanism based on the 802.1p priorities in converged Ethernet trac received on an interface and is
enabled by default when you enable DCB.
As an enhancement to the existing Ethernet pause mechanism, PFC stops trac transmission for specied priorities (Class of
Service (CoS) values) without impacting other priority classes. Dierent trac types are assigned to dierent priority classes.
When trac congestion occurs, PFC sends a pause frame to a peer device with the CoS priority values of the trac that is to be
stopped. Data Center Bridging Exchange protocol (DCBx) provides the link-level exchange of PFC parameters between peer
devices. PFC allows network administrators to create zero-loss links for Storage Area Network (SAN) trac that requires no-drop
service, while retaining packet-drop congestion management for Local Area Network (LAN) trac.
To ensure complete no-drop service, apply the same DCB input policy with the same pause time and dot1p priorities on all PFC-
enabled peer interfaces.
To congure PFC and apply a PFC input policy to an interface, follow these steps.
1. Create a DCB input policy to apply pause or ow control for specied priorities using a congured delay time.
CONFIGURATION mode
dcb-input policy-name
The maximum is 32 alphanumeric characters.
2. Congure the link delay used to pause specied priority trac.
DCB INPUT POLICY mode
pfc link-delay value
One quantum is equal to a 512-bit transmission.
The range (in quanta) is from 712 to 65535.
The default is 45556 quantum in link delay.
3. Congure the CoS trac to be stopped for the specied delay.
DCB INPUT POLICY mode
pfc priority priority-range
Enter the 802.1p values of the frames to be paused.
The range is from 0 to 7.
The default is none.
Maximum number of loss less queues supported on the switch: 2.
Separate priority values with a comma. Specify a priority range with a dash, for example: pfc priority 1,3,5-7.
4. Enable the PFC conguration on the port so that the priorities are included in DCBx negotiation with peer PFC devices.
DCB INPUT POLICY mode
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Data Center Bridging (DCB)