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Port Traffic Controls
Guaranteed Minimum Bandwidth (GMB)
Guaranteed Minimum Bandwidth (GMB)
Introduction
Guaranteed Minimum Bandwidth (GMB) provides a method for ensuring that
each of a given port’s outbound traffic priority queues has a specified mini-
mum consideration for sending traffic out on the link to another device. This
can prevent a condition where applications generating lower-priority traffic
in the network are frequently or continually "starved" by high volumes of
higher-priority traffic. You can configure GMB per-port.
Terminology
Oversubscribed Queue:
The condition where there is insufficient bandwidth
allocated to a particular outbound priority queue for a given port. If additional,
unused bandwidth is not available, the port delays or drops the excess traffic.
GMB Operation
The switch services per-port outbound traffic in a descending order of priority;
that is, from the highest priority to the lowest priority. By default, each port
offers eight prioritized, outbound traffic queues. Tagged VLAN traffic is prior-
itized according to the 802.1p priority the traffic carries. Untagged VLAN
traffic is assigned a priority of “
0
” (normal).
Feature
Default
Menu
CLI
Web
bandwidth-min output
Per-Queue:
2%-3%-30%-10%
10%-10%-15%-20%
n/a
n/a
show bandwidth output [
port-list
]
n/a
n/a
n/a
3500-5400-6200-8200-MCG-Jan08-K_13_01.book Page 19 Monday, January 28, 2008 10:04 AM