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dot1p Value in
the Incoming
Frame
Egress Queue Assignment
0 0
1 0
2 0
3 1
4 2
5 3
6 3
7 3
NOTE: If you reconfigure the global dot1p-queue mapping, an automatic re-election of the DCBX configuration source port
is performed (refer to Configuration Source Election).
Configure Enhanced Transmission Selection
ETS provides a way to optimize bandwidth allocation to outbound 802.1p classes of converged Ethernet traffic.
Different traffic types have different service needs. Using ETS, you can create groups within an 802.1p priority class to
configure different treatment for traffic with different bandwidth, latency, and best-effort needs.
For example, storage traffic is sensitive to frame loss; interprocess communication (IPC) traffic is latency-sensitive. ETS allows
different traffic 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 configure 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 traffic classes.
3. Configure 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 configuration is handled as follows:
● ETS TLVs are supported in DCBx versions CIN, CEE, and IEEE2.5.
● The DCBx port-role configurations determine the ETS operational parameters (refer to Configure a DCBx Operation).
● ETS configurations 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 configurations are ignored and existing ETS configurations are reset to the previously configured 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/traffic class group (TCG) ID 15 represents a non-ETS priority group. Any priority
group configured 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 flow in a priority group. A single flow 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 flow in any priority group.
CIN supports only the dot1p priority-queue assignment in a priority group. To configure a dot1p priority flow in a priority
group to operate with link strict priority, you configure: The dot1p priority for strict-priority scheduling (strict-priority
command; Enabling Strict-Priority Queueing).
FC Flex IO Modules
933