Priority-based Flow Control Configuration

Priority-based Flow Control (PFC) feature supports lossless Ethernet for selected traffic classes in congested network environments.

This chapter shows how to:

•

Enable PFC on a bridge and interface

•

Configure priorities and link delay allowance for PFC

On Tomahawk3 (TH3) platforms and LTSW platforms (Tomahawk4 (TH4) platforms, Tomahawk5 (TH5) platforms and Trident4 (TD4) platforms ), performing add, delete, or update operations on PFC will cause a system-wide traffic interruption, resulting in configured session flaps.

Topology

Figure 56. PFC Enabled Bridge

Configuring a Bridge and Interface for PFC

#configure terminal	Enter configure mode
(config)#bridge 1 protocol ieee vlan-bridge	Create bridge 1 as an IEEE VLAN-enabled bridge
(config)#data-center-bridging enable bridge 1	Enables DCB on the bridge
(config)#priority-flow-control enable bridge 1	Enables PFC on the bridge
(config)#interface eth1	Configure interface eth1
(config-if)#switchport	Configure eth1 as a layer 2 port
(config-if)#bridge-group 1	Configure eth1 in bridge group 1
(config-if)#lldp-agent	Enter into LLDP agent mode.
(lldp-agent)#set lldp enable txrx	Configure LLDP for transmit and receive mode on eth1
(lldp-agent)#lldp tlv ieee-8021-org-specific data-center-bridging select	Configure LLDP to send an IEEE 802.1 organizationally specific TLV set in the packet
(lldp-agent)#exit	Exit from LLDP mode.
(config-if)#priority-flow-control mode on	Configure the advertise flag and start sending DCBX TLVs in LLDP messages

Configuring Priorities and Link Delay Allowance for PFC

#configure terminal	Enter Configure Mode.
(config)#bridge 1 protocol ieee vlan-bridge	Create bridge 1 as an IEEE VLAN-enabled bridge
(config)#data-center-bridging enable bridge 1	Enables DCB on the bridge
(config)#priority-flow-control enable bridge 1	Enables PFC on the bridge
(config)#interface eth1	Configure interface eth1
(config-if)#switchport	Configure eth1 as a layer 2 port
(config-if)#bridge-group 1	Configure eth1 in bridge group 1
(config-if)#lldp-agent	Enter into LLDP agent mode.
(lldp-agent)#set lldp enable txrx	Configure LLDP for transmit and receive mode on eth1
(lldp-agent)#llldp tlv ieee-8021-org-specific data-center-bridging select	Configure LLDP to send an IEEE 802.1 organizationally specific TLV set in the packet
(lldp-agent)#exit	Exit from LLDP mode.
(config-if)#priority-flow-control mode on	Configure the advertise flag and start sending DCBX TLVs in LLDP messages
(config-if)#priority-flow-control cap 4	Configure the maximum number of PFC priorities
(config-if)#priority-flow-control enable priority 2 4 5	Enable PFC on priorities 2, 4, and 5
(config-if)#priority-flow-control link-delay-allowance 34567	Configure the link delay allowance

Validation

1. Verify the default data set.