Dell PowerEdge XL 5133-4 MXL 10/40GbE Switch IO Module FTOS Command Reference - Page 71

When DCB is Enabled, Lossless Traffic Handling,

Page 71 highlights

Figure 6-4. show interfaces Command Example: DCB disabled and Flow Control enabled FTOS#show interfaces tengigabitethernet 0/2 interface TenGigabitEthernet 0/2 mtu 12000 portmode hybrid switchport auto vlan flowcontrol rx on tx off dcb-policy input smux-dcb-in dcb-policy output smux-dcb-out ! protocol lldp advertise management-tlv system-name dcbx port-role auto-downstream no shutdown When DCB is Enabled When a server-facing interface receives DCBX protocol packets, it automatically enables DCB and disables link-level flow control. The DCB input and output policies and the flow control configuration are removed as shown in Figure 6-5. When no DCBX TLVs are received on a DCB-enabled interface for 180 seconds, DCB is automatically disabled and flow control is re-enabled. When all 10GbE server-facing interfaces have DCB disabled, DCB is also disabled on all 40GbE uplink interfaces. Figure 6-5. show interfaces Command Example: DCB enabled and Flow Control disabled FTOS#show interfaces tengigabitethernet 0/2 interface TenGigabitEthernet 0/2 mtu 12000 auto vlan ! port-channel-protocol LACP port-channel 1 mode active ! protocol lldp advertise management-tlv system-name dcbx port-role auto-downstream no shutdown 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. Lossless traffic is not guaranteed when it is transmitted on a PFC-enabled port and received on a link-level flow control-enabled port, or transmitted on a link-level flow control-enabled port and received on a PFC-enabled port. Data Center Bridging (DCB) | 57

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Data Center Bridging (DCB)
|
57
Figure 6-4.
show interfaces Command Example: DCB disabled and Flow Control enabled
When DCB is Enabled
When a server-facing interface receives DCBX protocol packets, it automatically enables DCB and
disables link-level flow control. The DCB input and output policies and the flow control configuration are
removed as shown in
Figure 6-5
.
When no DCBX TLVs are received on a DCB-enabled interface for 180 seconds, DCB is automatically
disabled and flow control is re-enabled. When all 10GbE server-facing interfaces have DCB disabled,
DCB is also disabled on all 40GbE uplink interfaces.
Figure 6-5.
show interfaces Command Example: DCB enabled and Flow Control disabled
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.
Lossless traffic is not guaranteed when it is transmitted on a PFC-enabled port and received on a link-level
flow control-enabled port, or transmitted on a link-level flow control-enabled port and received on a
PFC-enabled port.
FTOS#show interfaces
tengigabitethernet 0/2
interface TenGigabitEthernet 0/2
mtu 12000
portmode hybrid
switchport
auto vlan
flowcontrol rx on tx off
dcb-policy input smux-dcb-in
dcb-policy output smux-dcb-out
!
protocol lldp
advertise management-tlv system-name
dcbx port-role auto-downstream
no shutdown
FTOS#show interfaces
tengigabitethernet 0/2
interface TenGigabitEthernet 0/2
mtu 12000
auto vlan
!
port-channel-protocol LACP
port-channel 1 mode active
!
protocol lldp
advertise management-tlv system-name
dcbx port-role auto-downstream
no shutdown