224
CN4093 Application Guide for N/OS 8.4
Using 802.1p Priorities to Provide QoS
Enterprise
NOS
provides
Quality
of
Service
functions
based
on
the
priority
bits
in
a
packet’s
VLAN
header.
(The
priority
bits
are
defined
by
the
802.1p
standard
within
the
IEEE
802.1q
VLAN
header.)
The
802.1p
bits,
if
present
in
the
packet,
specify
the
priority
that
should
be
given
to
packets
during
forwarding.
Packets
with
a
numerically
higher
(non
‐
zero)
priority
are
given
forwarding
preference
over
packets
with
lower
priority
bit
value.
The
IEEE
802.1p
standard
uses
eight
levels
of
priority
(0
‐
7).
Priority
7
is
assigned
to
highest
priority
network
traffic,
such
as
OSPF
or
RIP
routing
table
updates,
priorities
5
‐
6
are
assigned
to
delay
‐
sensitive
applications
such
as
voice
and
video,
and
lower
priorities
are
assigned
to
standard
applications.
A
value
of
0
(zero)
indicates
a
“best
effort”
traffic
prioritization,
and
this
is
the
default
when
traffic
priority
has
not
been
configured
on
your
network.
The
CN4093
can
filter
packets
based
on
the
802.1p
values,
and
it
can
assign
or
overwrite
the
802.1p
value
in
the
packet.
Figure 24.
Layer
2
802.1q/802.1p
VLAN
Tagged
Packet
Ingress
packets
receive
a
priority
value,
as
follows:
Tagged
packets
—CN4093
reads
the
802.1p
priority
in
the
VLAN
tag.
Untagged
packets
—CN4093
tags
the
packet
and
assigns
an
802.1p
priority,
based
on
the
port’s
default
priority.
Egress
packets
are
placed
in
a
COS
queue
based
on
the
priority
value,
and
scheduled
for
transmission
based
on
the
scheduling
weight
of
the
COS
queue.
To
configure
a
port’s
default
802.1p
priority
value,
use
the
following
commands.
See
for
details
on
scheduling
weights.
CN 4093(config)#
interface port 1
CN 4093(config-if)#
dot1p
<802.1p
value
(0
‐
7)>
CN 4093(config-if)#
exit
7 6 5 4 3 2 1 0
Priority
7 6 5 4 3 2 1 0
VLAN Identifier (VID)
SFD
DMAC SMAC
Tag
E Type Data
FCS
Preamble
Summary of Contents for Flex System Fabric CN4093
Page 27: ... Copyright Lenovo 2017 27 Part 1 Getting Started ...
Page 28: ...28 CN4093 Application Guide for N OS 8 4 ...
Page 58: ...58 CN4093 Application Guide for N OS 8 4 ...
Page 72: ...72 CN4093 Application Guide for N OS 8 4 ...
Page 85: ... Copyright Lenovo 2017 85 Part 2 Securing the Switch ...
Page 86: ...86 CN4093 Application Guide for N OS 8 4 ...
Page 98: ...98 CN4093 Application Guide for N OS 8 4 ...
Page 112: ...112 CN4093 Application Guide for N OS 8 4 ...
Page 136: ...136 CN4093 Application Guide for N OS 8 4 ...
Page 156: ...156 CN4093 Application Guide for N OS 8 4 ...
Page 192: ...192 CN4093 Application Guide for N OS 8 4 ...
Page 228: ...228 CN4093 Application Guide for N OS 8 4 ...
Page 229: ... Copyright Lenovo 2017 229 Part 4 Advanced Switching Features ...
Page 230: ...230 CN4093 Application Guide for N OS 8 4 ...
Page 298: ...298 CN4093 Application Guide for N OS 8 4 ...
Page 382: ...382 CN4093 Application Guide for N OS 8 4 ...
Page 392: ...392 CN4093 Application Guide for N OS 8 4 ...
Page 416: ...416 CN4093 Application Guide for N OS 8 4 ...
Page 452: ...452 CN4093 Application Guide for N OS 8 4 ...
Page 466: ...466 CN4093 Application Guide for N OS 8 4 ...
Page 496: ...496 CN4093 Application Guide for N OS 8 4 ...
Page 508: ...508 CN4093 Application Guide for N OS 8 4 ...
Page 510: ...510 CN4093 Application Guide for N OS 8 4 ...
Page 514: ...514 CN4093 Application Guide for N OS 8 4 ...
Page 538: ...538 CN4093 Application Guide for N OS 8 4 ...
Page 539: ... Copyright Lenovo 2017 539 Part 7 Network Management ...
Page 540: ...540 CN4093 Application Guide for N OS 8 4 ...
Page 554: ...554 CN4093 Application Guide for N OS 8 4 ...
Page 576: ...576 CN4093 Application Guide for N OS 8 4 ...
Page 596: ...596 CN4093 Application Guide for N OS 8 4 ...
Page 604: ...604 CN4093 Application Guide for N OS 8 4 ...
Page 609: ... Copyright Lenovo 2017 609 Part 9 Appendices ...
Page 610: ...610 CN4093 Application Guide for N OS 8 4 ...
Page 626: ...626 CN4093 Application Guide for N OS 8 4 ...
Page 633: ......
Page 634: ...Part Number 00MY375 Printed in USA IP P N 00MY375 ...