Access, Core, iSCSI Switch Fabric, MXL (Blade), QoS/CoS/DCB, S4810

Force10 DCB Configuration – S4810 + MXL Sample / Example

.

First, some background on DCB itself.

DCB is an extension to Ethernet that enables the dedication of resources in the converged network. To ensure lossless delivery and latency-sensitive scheduling of storage, service traffic, and I/O convergence of LAN over a unified fabric, IEEE data centre bridging adds the following extensions to a classical Ethernet network:

      • 802.1Qbb – Priority-based Flow Control (PFC)
      • 802.1Qaz – Enhanced Transmission Selection (ETS)
      • Data Center Bridging Exchange (DCBX) protocol
  • PFC

The DCB framework allows administrators to define traffic flows (e.g.iSCSI) that are put into a lossless queue or one with Priority Flow Control (PFC). This means that the SAN traffic flows will be separated from the LAN flows. Consequently, this will permit LAN traffic to pause independent of SAN traffic that shares the same backplane/fabric as the LAN traffic. In multi-protocol links, PFC can address sudden bursts in one type of traffic,  so that it does not affect other traffic types and no frames are lost due to congestion.

data center bridging - priority flow control

Unlike the traditional flow control mechanism, which is implemented on a link bases (thus pausing all traffic on a link, regardless of various traffic types that may be sharing the same link), DCB implements its mechanisms on a flow base. Instead of stopping all traffic on a link (as performed by the traditional Ethernet pause mechanism), PFC pauses traffic on a link according to the 802.1p priority set on a traffic type. You can thus treat iSCSI traffic as loss-less, while allowing for loss in case of LAN traffic congestion on the same physical interface.

Enhanced Transmission Selection

  • ETS

DCB also allows IT administrators to divide the available network bandwidth between these different traffic types by setting parameters. The parameters or bandwidth allocations are known as Enhanced Transmission Selection (ETS), and are assigned to traffic in the different queues for LAN or storage. Bandwidth allocation and queue scheduling for each group ensure each traffic type is correctly prioritized and receives its allocated bandwidth.

Lastly, DCB passes the PFC and ETS parameters from the network switches out to the attached devices via DCB eXchange (DCBx) packets.

DCB Configuration can be achieved through the following commands/parameters on Force10 FTOS:

Mode/Prompt

Parameters

Arguments

Comments

Config)#

interface range TenGigabitEthernet 0/0 – xx Range of interfaces imapcted

Config-int)#

   dcb-policy input pfc-policy Apply the input policy with the PFC configuration to an ingress interface.

Config-int)#

   dcb-policy output ets-policy Apply the output policy with the ETS configuration to an egress interface.

Config-int)#

exit
    Creating a QoS ETS Output Policy

Config)#

qos-policy-output lan ets Create a QoS output policy to configure the ETS bandwidth allocation and scheduling for priority traffic.

Config-POLICY-MAP-OUT-ETS)#

   bandwidth-percentage 70

Config-POLICY-MAP-OUT-ETS)#

qos-policy-output iscsi ets Configure the bandwidth percentage allocated to priority traffic in port queues. The sum of bandwidth percentage assigned to dot1p priorities/queues in a priority group should be 100%.

Config-POLICY-MAP-OUT-ETS)#

   bandwidth-percentage 30

Config-POLICY-MAP-OUT-ETS)#

exit

Config)#

dcb stack-unit all pfc-buffering pfc-ports 64 pfc-queues 2 Configure the PFC buffer for all switches in the stack. Default: enabled on all ports.

Config)#

dcb-input pfc-policy Create a DCB input policy to apply pause/flow control for specified priorities using a configured delay time.

Config-DCB INPUT POLICY)#

   pfc priority 4 Configure the CoS traffic to be stopped for the specified delay. Enter the 802.1p values of the frames to be paused.

Config-DCB INPUT POLICY)#

exit
Creating an ETS Priority Group

Config)#

priority-group lan Create an ETS priority group to use with an ETS output policy.

Config-priority-group)#

   priority-list 0-3,5-7 Configure the 802.1p priorities for the traffic on which you want to apply an ETS output policy. Valid values: 0 to 7. Default: None.

Config-priority-group)#

   set-pgid 1 Configure the priority-group identifier. Valid values: 0 to 7.

Config-priority-group)#

exit

Config)#

priority-group iscsi

Config-priority-group)#

   priority-list 4

Config-priority-group)#

   set-pgid 0

Config-priority-group)#

exit
Applying an ETS Output Policy for a Priority Group to an Interface

Config)#

dcb-output ets-policy Create a DCB output policy to associate an ETS configuration with priority traffic.

Config-DCB OUTPUT POLICY)#

priority-group lan qos-policy lan Associate the 802.1p priority traffic in a priority group with the ETS configuration in a QoS output policy.

Config-DCB OUTPUT POLICY)#

priority-group iscsi qos-policy iscsi

Config-DCB OUTPUT POLICY)#

exit

Config)#

dcb-policy input stack-unit all stack-ports all dcb Apply the specified DCB input policy on all ports of the switch/stack.

.

About these ads

About Hasan Mansur

Hasan Mansur --------------------- bis vincit qui se vincit in victoria.

Discussion

No comments yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 86 other followers

%d bloggers like this: