Administrator Guide

NOTE: If you recongure the global dot1p-queue mapping, an automatic re-election of the DCBX conguration source
port is performed (refer to Conguration Source Election).
Congure Enhanced Transmission Selection
ETS provides a way to optimize bandwidth allocation to outbound 802.1p classes of converged Ethernet trac.
Dierent trac types have dierent service needs. Using ETS, you can create groups within an 802.1p priority class to congure
dierent treatment for trac with dierent bandwidth, latency, and best-eort needs.
For example, storage trac is sensitive to frame loss; interprocess communication (IPC) trac is latency-sensitive. ETS allows
dierent trac types to coexist without interruption in the same converged link by:
• Allocating a guaranteed share of bandwidth to each priority group.
• Allowing each group to exceed its minimum guaranteed bandwidth if another group is not fully using its allotted bandwidth.
To congure ETS and apply an ETS output policy to an interface, you must:
1. Create a Quality of Service (QoS) output policy with ETS scheduling and bandwidth allocation settings.
2. Create a priority group of 802.1p trac classes.
3. Congure a DCB output policy in which you associate a priority group with a QoS ETS output policy.
4. Apply the DCB output policy to an interface.
ETS Operation with DCBx
The following section describes DCBx negotiation with peer ETS devices.
In DCBx negotiation with peer ETS devices, ETS conguration is handled as follows:
• ETS TLVs are supported in DCBx versions CIN, CEE, and IEEE2.5.
• The DCBx port-role congurations determine the ETS operational parameters (refer to Congure a DCBx Operation).
• ETS congurations received from TLVs from a peer are validated.
• If there is a hardware limitation or TLV error:
– DCBx operation on an ETS port goes down.
– New ETS congurations are ignored and existing ETS congurations are reset to the previously congured ETS output policy
on the port or to the default ETS settings if no ETS output policy was previously applied.
• ETS operates with legacy DCBx versions as follows:
– In the CEE version, the priority group/trac class group (TCG) ID 15 represents a non-ETS priority group. Any priority group
congured with a scheduler type is treated as a strict-priority group and is given the priority-group (TCG) ID 15.
– The CIN version supports two types of strict-priority scheduling:
* Group strict priority: Use this to increase its bandwidth usage to the bandwidth total of the priority group and allow a
single priority ow in a priority group. A single ow in a group can use all the bandwidth allocated to the group.
* Link strict priority: Use this to increase to the maximum link bandwidth and allow a ow in any priority group.
CIN supports only the dot1p priority-queue assignment in a priority group. To congure a dot1p priority ow in a priority group to
operate with link strict priority, you congure: The dot1p priority for strict-priority scheduling (strict-priority command;
Enabling Strict-Priority Queueing).
If you congure only the priority group in an ETS output policy or only the dot1p priority for strict-priority scheduling, the ow is
handled with group strict priority.
Conguring Bandwidth Allocation for DCBx CIN
After you apply an ETS output policy to an interface, if the DCBx version used in your data center network is CIN, you may need to
congure a QoS output policy to overwrite the default CIN bandwidth allocation.
This default setting divides the bandwidth allocated to each port queue equally between the dot1p priority trac assigned to the
queue.
For more information, refer to Allocating Bandwidth to Queue.
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FC Flex IO Modules