Quality of Service
QoS Properties
Cisco Small Business SG200 Series 8-port Smart Switches Administration Guide
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The switch supports four egress queues for each port or LAG. Queue1 has the
lowest priority and queue 4 has the highest priority.
The pages in the Quality of Service menu enable you to define properties of the
queues, and to associate with them traffic that has particular characteristics or
arrives on particular interfaces. You can also create rate limit profiles that define
criteria for determining whether a port is receiving more traffic than it can handle.
You can then assign the rate limit profiles to ports.
QoS Properties
You can configure switch ports to assign traffic to egress queues based on the
priority information encoded in Ethernet frames or IP packet headers. Or traffic
might use a default priority value configured on the port where it arrives. When a
port is configured to use the encoded priority value (such as the 802.1p, IP
precedence, or DSCP value), it is considered a
trusted
port. A port that is
configured to use its own priority value, rather than the value encoded in the frame
or packet, to make queue assignment decisions is considered
untrusted
.
If a port is configured as trusted but the frame or packet does not have priority
information, then the default port priority is assigned to the packet. The default
port priority is zero.
You can use the
VLAN Management
>
Interface Settings
page to change the
value of the VLAN Priority.
You can use the
QoS Properties
page to define a port as trusted or untrusted and
to configure which priority values it trusts.
To configure the trust mode on a port or LAG:
STEP 1
Click
Quality of Service
>
QoS Properties
in the navigation window.
STEP 2
Use the Interface Type menu to display ports or LAGs in the Trust Mode
Configuration Table.
STEP 3
Select the interface to configure and click
Edit
.
STEP 4
To specify the type of priority values to use to determine the egress queues of the
packets, select one of the following trust modes:
•
untrusted
—The port assigns its own default 802.1p priority (0).
•
trust dot1p
—The port uses the 802.1p priority value in VLAN-tagged
Ethernet frames. For untagged frames, the port’s default priority is assigned.
