API Guide

Enhanced transmission selection
ETS provides customized bandwidth allocation to 802.1p classes of traffic. Assign different amounts of bandwidth to Ethernet,
FCoE, or iSCSI traffic classes that require different bandwidth, latency, and best-effort treatment during network congestion.
ETS divides traffic into different priority groups using their 802.1p priority value. To ensure that each traffic class is correctly
prioritized and receives the required bandwidth, configure bandwidth and queue scheduling for each priority group. To prioritize
low-latency storage and server-cluster traffic, allocate more bandwidth to a priority group. To rate-limit best-effort LAN traffic,
allocate less bandwidth to a different priority group.
ETS configuration notes
● ETS is supported on Layer2 (L2) 802.1p priority (dot1p 0 to 7) and Layer 3 (L3) DSCP (0 to 63) traffic. FCoE traffic uses
dot1p priority 3 — iSCSI storage traffic uses dot1p priority 4.
● Apply these maps and policies on interfaces:
○ Trust maps — OS10 interfaces do not honor the L2 and L3 priority fields in ingress traffic by default. Create a trust map
to honor dot1p and DSCP classes of lossless traffic. A trust map does not change ingress dot1p and DSCP values in
egress flows. In a trust map, assign a qos-group traffic class to trusted dot1p/DSCP values. A qos-group number is
used only internally to schedule classes of ingress traffic.
○ QoS map — Create a QoS map to assign trusted dot1p and DSCP traffic classes to lossless queues.
○ Ingress trust policy — Configure a service policy to trust dot1p values in ingress traffic.
○ Egress queuing policy — Configure ETS for egress traffic by assigning bandwidth to match 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 traffic is sent to control queues, which have a strict-priority that is higher than data traffic queues. ETS-
allocated bandwidth is not supported on a strict-priority queue. A strict priority queue receives bandwidth only from DCBX
type, length, values (TLVs).
● The CEE/IEEE2.5 versions of ETS TLVs are supported. ETS configurations are received in a TLV from a peer.
Configure ETS
ETS provides traffic prioritization for lossless storage, latency-sensitive, and best-effort data traffic on the same link.
● Configure classes of dot1p and DSCP traffic, and assign them to lossless queues.
● Allocate guaranteed bandwidth to each lossless queue. If another queue does not use its share, an ETS queue can exceed
the amount of allocated bandwidth.
ETS is disabled by default on all interfaces.
1. Configure trust maps of dot1p and DSCP values in CONFIGURATION mode. A trust map does not modify ingress values in
output flows. Assign a qos-group, traffic class from 0 to 7, to trusted dot1p/DSCP values in TRUST mode. A qos-group
Converged data center services
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