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Configuring Lossless Queues
DCB also supports the manual configuration of lossless queues on an interface when PFC mode is disabled in a DCB map, apply the
map on the interface. The configuration of no-drop queues provides flexibility for ports on which PFC is not needed, but lossless
traffic should egress from the interface.
Configuring no-drop queues is applicable only on the interfaces which do not need PFC.
Example:
Port A —> Port B
Port C —> Port B
PFC no-drop queues are configured for queues 1, 2 on Port B. PFC capability is enabled on priorities 3, 4 on PORT A and C.
Port B acting as Egress
During the congestion, [traffic pump on priorities 3 and 4 from PORT A and PORT C is at full line rate], PORT A and C send out the
PFCs to rate the traffic limit. Egress drops are not observed on Port B since traffic flow on priorities is mapped to loss less queues.
Port B acting as Ingress
If the traffic congestion is on PORT B , Egress DROP is on PORT A or C, as the PFC is not enabled on PORT B.
Refer the following configuration for queue to dot1p mapping:
Dell(conf)#do show qos dot1p-queue-mapping
Dot1p Priority : 0 1 2 3 4 5 6 7 -> On ingress interfaces[Port A and C] we used
the PFC on priority level.
Queue : 0 0 0 1 2 3 3 3 -> On Egress interface[Port B] we used no-drop
queues.
Lossless traffic egresses out the no-drop queues. Ingress 802.1p traffic from PFC-enabled peers is automatically mapped to the no-
drop egress queues.
When configuring lossless queues on a port interface, consider the following points:
•
By default, no lossless queues are configured on a port.
•
A limit of two lossless queues is supported on a port. If the number of lossless queues configured exceeds the maximum
supported limit per port (two), an error message is displayed. Reconfigure the value to a smaller number of queues.
•
If you configure lossless queues on an interface that already has a DCB map with PFC enabled (
pfc on
), an error message is
displayed.
Table 19. Configuring Lossless Queues on a Port Interface
Step
Task
Command
Command Mode
1
Enter INTERFACE Configuration mode.
interface
{
tengigabitEthernet
slot
/
port
[
/subport
] |
fortygigabitEthernet
slot
/
port
}
CONFIGURATION
2
Open a DCB map and enter DCB map configuration
mode.
dcb-map
name
INTERFACE
3
Disable PFC.
no pfc mode on
DCB MAP
Data Center Bridging (DCB)
251
Содержание S4048-ON
Страница 1: ...Dell Configuration Guide for the S4048 ON System 9 9 0 0 ...
Страница 146: ...Figure 14 BFD Three Way Handshake State Changes 146 Bidirectional Forwarding Detection BFD ...
Страница 477: ...Figure 68 Inspecting Configuration of LAG 10 on ALPHA Link Aggregation Control Protocol LACP 477 ...
Страница 480: ...Figure 70 Inspecting a LAG Port on BRAVO Using the show interface Command 480 Link Aggregation Control Protocol LACP ...
Страница 481: ...Figure 71 Inspecting LAG 10 Using the show interfaces port channel Command Link Aggregation Control Protocol LACP 481 ...
Страница 522: ...Figure 87 Configuring Interfaces for MSDP 522 Multicast Source Discovery Protocol MSDP ...
Страница 523: ...Figure 88 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 523 ...
Страница 524: ...Figure 89 Configuring PIM in Multiple Routing Domains 524 Multicast Source Discovery Protocol MSDP ...
Страница 528: ...Figure 91 MSDP Default Peer Scenario 1 528 Multicast Source Discovery Protocol MSDP ...
Страница 529: ...Figure 92 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 529 ...
Страница 530: ...Figure 93 MSDP Default Peer Scenario 3 530 Multicast Source Discovery Protocol MSDP ...
Страница 633: ...Policy based Routing PBR 633 ...
Страница 777: ...Figure 119 Single and Double Tag TPID Match Service Provider Bridging 777 ...
Страница 778: ...Figure 120 Single and Double Tag First byte TPID Match 778 Service Provider Bridging ...