Users Guide

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Supported Releases 10.3.0E or later
Enhanced transmission selection
Enhanced transmission selection (ETS) provides customized bandwidth allocation to 802.1p classes of trac. Assign dierent amounts of
bandwidth to trac classes (Ethernet, FCoE, or iSCSI) that require dierent bandwidth, latency, and best-eort treatment during network
congestion.
ETS divides trac into dierent priority groups using their 802.1p priority value. To ensure that each trac class is correctly prioritized and
receives required bandwidth, congure bandwidth and queue scheduling for each priority group. You can allocate more bandwidth to a
priority group to prioritize low-latency storage and server-cluster trac. Allocate less bandwidth to a dierent priority group to rate-limit
best-eort LAN trac.
ETS conguration notes
• ETS is supported on L2 802.1p priority (dot1p 0 to 7) and L3 DSCP (0 to 63) trac. FCoE trac uses dot1p priority 3 — iSCSI storage
trac uses dot1p priority 4.
• Apply these maps and policies on interfaces:
– Trust maps — OS10 interfaces do not honor the L2 and L3 priority elds in ingress trac by default. Create a trust map to honor
dot1p and DSCP classes of lossless trac. A trust map does not change ingress dot1p and DSCP values in egress ows. In a trust
map, assign a qos-group (trac class) to trusted dot1p/DSCP values. A qos-group number is used only internally to schedule
classes of ingress trac.
– QoS map — Create a QoS map to assign trusted dot1p and DSCP trac classes to lossless queues.
– Ingress trust policy — Congure a service policy to trust dot1p values in ingress trac.
– Egress queuing policy — Congure ETS for egress trac by assigning bandwidth to matching lossless queues in queuing class
and policy maps.
• Apply both PFC network-qos (input) and ETS queuing (output) policies on an interface to ensure lossless transmission.
• An ETS-enabled interface operates with dynamic weighted round robin (DWRR) or strict priority scheduling.
• OS10 control trac is sent to control queues, which have a strict priority that is higher than data trac queues. ETS-allocated
bandwidth is not supported on a strict priority queue. A strict priority queue receives bandwidth only from DCBX TLVs.
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Converged data center services