Dell PowerEdge FX2 Dell PowerEdge FN I/O Aggregator Configuration Guide 9.6(0 - Page 35

When DCB is Disabled Default, When DCB is Enabled

Page 35 highlights

When DCB is Disabled (Default) By default, Aggregator interfaces operate with DCB disabled and linklevel flow control enabled. When an interface comes up, it is automatically configured with: • Flow control enabled on input interfaces. • A DCB-MAP policy is applied with PFC disabled. The following example shows a default interface configuration with DCB disabled and link-level flow control enabled. show interfaces Command Example: DCB disabled and Flow Control enabled Dell#show running-config interface te 0/4 ! interface TenGigabitEthernet 0/4 mtu 12000 portmode hybrid switchport auto vlan flowcontrol rx on tx off dcb-map DCB_MAP_PFC_OFF ! protocol lldp advertise management-tlv management-address system-name dcbx port-role auto-downstream no shutdown Dell# When DCB is Enabled When an interface receives a DCBx protocol packet, it automatically enables DCB and disables link-level flow control. The dcb-map and flow control configurations are removed as shown in the following example. show interfaces Command Example: DCB enabled and Flow Control disabled Dell#show running-config interface te 0/3 ! interface TenGigabitEthernet 0/3 mtu 12000 portmode hybrid switchport auto vlan ! protocol lldp advertise management-tlv management-address system-name dcbx port-role auto-downstream no shutdown Dell# When no DCBx TLVs are received on a DCB-enabled interface for 180 seconds, DCB is automatically disabled and flow control is re-enabled. Lossless Traffic Handling In auto-DCB-enable mode, Aggregator ports operate with the auto-detection of DCBx traffic. At any moment, some ports may operate with link-level flow control while others operate with DCB-based PFC enabled. As a result, lossless traffic is ensured only if traffic ingresses on a PFC-enabled port and egresses on another PFC-enabled port. Data Center Bridging (DCB) 35

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When DCB is Disabled (Default)
By default, Aggregator interfaces operate with DCB disabled and link-
level flow control enabled. When an interface comes up, it is automatically configured with:
Flow control enabled on input interfaces.
A DCB-MAP policy is applied with PFC disabled.
The following example shows a default interface configuration with DCB disabled and link-level flow
control enabled.
show interfaces Command Example: DCB disabled and Flow Control enabled
Dell#show running-config interface te 0/4
!
interface TenGigabitEthernet 0/4
mtu 12000
portmode hybrid
switchport
auto vlan
flowcontrol rx on tx off
dcb-map DCB_MAP_PFC_OFF
!
protocol lldp
advertise management-tlv management-address system-name
dcbx port-role auto-downstream
no shutdown
Dell#
When DCB is Enabled
When an interface receives a DCBx protocol packet, it automatically enables DCB
and disables link-level flow control. The dcb-map and flow control configurations are removed as shown
in the following example.
show interfaces Command Example: DCB enabled and Flow Control disabled
Dell#show running-config interface te 0/3
!
interface TenGigabitEthernet 0/3
mtu 12000
portmode hybrid
switchport
auto vlan
!
protocol lldp
advertise management-tlv management-address system-name
dcbx port-role auto-downstream
no shutdown
Dell#
When no DCBx TLVs are received on a DCB-enabled interface for 180 seconds, DCB is automatically
disabled and flow control is re-enabled.
Lossless Traffic Handling
In auto-DCB-enable mode, Aggregator ports operate with the auto-detection
of DCBx traffic. At any moment, some ports may operate with link-level flow control while others operate
with DCB-based PFC enabled.
As a result, lossless traffic is ensured only if traffic ingresses on a PFC-enabled port and egresses on
another PFC-enabled port.
Data Center Bridging (DCB)
35