Figure 27. Illustration of Traffic Congestion
The system supports loading two DCB_Config files:
•
FCoE converged traffic with priority 3.
•
iSCSI storage traffic with priority 4.
In the Dell Networking OS, PFC is implemented as follows:
•
PFC is supported on specified 802.1p priority traffic (dot1p 0 to 7) and is configured per interface. However, only two lossless queues
are supported on an interface: one for Fibre Channel over Ethernet (FCoE) converged traffic and one for Internet Small Computer
System Interface (iSCSI) storage traffic. Configure the same lossless queues on all ports.
•
PFC supports buffering to receive data that continues to arrive on an interface while the remote system reacts to the PFC operation.
•
PFC uses DCB MIB IEEE 802.1azd2.5 and PFC MIB IEEE 802.1bb-d2.2.
•
A dynamic threshold handles intermittent traffic bursts and varies based on the number of PFC priorities contending for buffers, while a
static threshold places an upper limit on the transmit time of a queue after receiving a message to pause a specified priority. PFC traffic
is paused only after surpassing both static and dynamic thresholds for the priority specified for the port.
•
By default, PFC is enabled when you enable DCB. If you have not loaded FCoE_DCB_Config and iSCSI_DCB_Config, DCB is disabled.
When you enable DCB globally, you cannot simultaneously enable link-level flow control.
•
Buffer space is allocated and de-allocated only when you configure a PFC priority on the port.
Enhanced Transmission Selection
Enhanced transmission selection (ETS) supports optimized bandwidth allocation between traffic types in multiprotocol (Ethernet, FCoE,
SCSI) links.
ETS allows you to divide traffic according to its 802.1p priority into different priority groups (traffic classes) and configure bandwidth
allocation and queue scheduling for each group to ensure that each traffic type is correctly prioritized and receives its required bandwidth.
For example, you can prioritize low-latency storage or server cluster traffic in a traffic class to receive more bandwidth and restrict best-
effort LAN traffic assigned to a different traffic class.
NOTE:
Use the following command to enable etsacl:
cam-acl l2acl 2 ipv4acl 2 ipv6acl 0 ipv4qos 0 l2qos 0
l2pt 0 ipmacacl 0 vman-qos 0 fcoeacl 2 etsacl 3
. After executing this command, you must save the
configuration and then reload the system.
The following figure shows how ETS allows you to allocate bandwidth when different traffic types are classed according to 802.1p priority
and mapped to priority groups.
254
Data Center Bridging (DCB)
Содержание S4048T-ON
Страница 1: ...Dell Configuration Guide for the S4048 ON System 9 11 2 1 ...
Страница 148: ...Figure 10 BFD Three Way Handshake State Changes 148 Bidirectional Forwarding Detection BFD ...
Страница 251: ...Dell Control Plane Policing CoPP 251 ...
Страница 363: ... RPM Synchronization GARP VLAN Registration Protocol GVRP 363 ...
Страница 511: ...Figure 64 Inspecting the LAG Configuration Link Aggregation Control Protocol LACP 511 ...
Страница 512: ...Figure 65 Inspecting Configuration of LAG 10 on ALPHA 512 Link Aggregation Control Protocol LACP ...
Страница 515: ...Figure 67 Inspecting a LAG Port on BRAVO Using the show interface Command Link Aggregation Control Protocol LACP 515 ...
Страница 516: ...Figure 68 Inspecting LAG 10 Using the show interfaces port channel Command 516 Link Aggregation Control Protocol LACP ...
Страница 558: ...Figure 84 Configuring Interfaces for MSDP 558 Multicast Source Discovery Protocol MSDP ...
Страница 559: ...Figure 85 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 559 ...
Страница 560: ...Figure 86 Configuring PIM in Multiple Routing Domains 560 Multicast Source Discovery Protocol MSDP ...
Страница 564: ...Figure 88 MSDP Default Peer Scenario 2 564 Multicast Source Discovery Protocol MSDP ...
Страница 565: ...Figure 89 MSDP Default Peer Scenario 3 Multicast Source Discovery Protocol MSDP 565 ...
Страница 729: ...protocol spanning tree pvst no disable vlan 300 bridge priority 4096 Per VLAN Spanning Tree Plus PVST 729 ...
Страница 841: ...Figure 115 Single and Double Tag TPID Match Service Provider Bridging 841 ...
Страница 842: ...Figure 116 Single and Double Tag First byte TPID Match 842 Service Provider Bridging ...