Administrator Guide

Data Center Bridging Features 1067
Enhanced Transmission Selection
Networks classify and prioritize traffic to provide different service
characteristics to end user traffic flows. Administrators may wish to guarantee
or limit bandwidth for certain traffic, ensure lossless behavior for other traffic,
and control the queue discipline/drop characteristics for best-effort traffic.
Additionally, it is desirable for a switch to support sharing bandwidth among
bursty sources while still enabling prioritization of time-sensitive or
management traffic that requires minimum latency.
Enhanced transmission selection (ETS) provides uniform management for
sharing bandwidth between congestion managed and traditional classes on a
single bridged network. Using priority-based processing and weight
allocations, Traffic Class Groups (TCGs) carrying different types of traffic
such as LAN, SAN, and management traffic can be configured to provide
minimum bandwidth guarantees, unused bandwidth sharing, and lossless or
best-effort transmit characteristics. Dell Networking N4000 Series switches
support strict priority and Weighted Deficit Round Robin (WDRR)
scheduling with up to two lossless traffic classes. WDRR schedules traffic
based on average bandwidth consumed vs. frame counts.
ETS Operation
The normal (default) operation of Dell Networking N-Series switches, when
uncongested, is that packets are scheduled for output in the order in which
they are received, that is, using FIFO scheduling. The class of service (CoS)
mechanism enables the administrator to schedule packets for output ahead of
other packets when the switch is congested, choose which type of packets to
drop when the switch is congested, and assign a minimum bandwidth
guarantee to ensure scheduling fairness. These mechanisms operate at the
CoS queue level; that is, the minimum bandwidth guarantees are made
across all configured CoS queues.
show lldp tlv-select
interface {all |
interface }
Display the interface TLV configuration for all interfaces
or for the specified interface.
show lldp dcbx interface
{all status | interface
[detail]}
Display the interface TLV configuration for all interfaces
or for the specified interface.
Command Purpose