Dell Force10 E300, Configuration Manual

Page: 871 / 1262

Quality of Service | 871
You can create a custom WRED profile or use on of the five pre-defined profiles listed in Table 41-7 .
Create WRED Profiles
To create a WRED profile:
1. Create a WRED profile using the command
wred
from CONFIGURATION mode.
2. The command
wred
places you in WRED mode. From this mode, specify minimum and maximum
threshold values using the command
threshold
.
Apply a WRED profile to traffic
Once you create a WRED profile you must specify to which traffic FTOS should apply the profile.
FTOS assigns a color (also called drop precedence)—red, yellow, or green—to each packet based on it
DSCP value before queuing it. DSCP is a 6 bit field. Dell Force10 uses the first three bits of this field (DP)
to determine the drop precedence. DP values of 110 and 100 map to yellow, and all other values map to
green. If you do not configure FTOS to honor DSCP values on ingress (
Honor DSCP values on ingress
packets on page 865 ) see all traffic defaults to green drop precedence.
Assign a WRED profile to either yellow or green traffic from QOS-POLICY-OUT mode using the
command
wred
.
Configure WRED for Storm Control
Configure WRED for Storm Control is supported only on platform
e
Storm control limits the percentage of the total bandwidth that broadcast traffic can consume on an
interface (if configured locally) or on all interfaces (if configured globally). For
storm-control broadcast 50
out
, the total bandwidth that broadcast traffic can consume on egress on a 1Gbs interface is 512Mbs. The
method by which packets are selected to be dropped is the "tail-drop" method, where packets exceeding
the specified rate are dropped.
Table 41-7. Pre-defined WRED Profiles
Default Profile
Name
Minimum
Threshold Maximum
Threshold
wred_drop 0 0
wred_ge_y 1024 2048
wred_ge_g 2048 4096
wred_teng_y 4096 8192
wred_teng_g 8192 16384