Cisco Sg3008 Manual

Quality of Service
Configuring QoS - General
493 Cisco Small Business 200, 300 and 500 Series Managed Switch Administration Guide (Internal Version) 
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Configuring QoS - General
The QoS Properties Page contains fields for setting the QoS mode for the system 
(Basic, Advanced, or Disabled, as described in the “QoS Modes” section). In 
addition, the default CoS priority for each interface can be defined.
Setting QoS Properties
To select the QoS mode:
STEP 1Click Quality of Service > General > QoS...

Quality of Service
Configuring QoS - General
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STEP  2Click Apply. The interface default CoS value is saved to Running Configuration file.
Configuring QoS Queues 
The device supports 4 for each interface. Queue number four is the highest 
priority queue. Queue number one is the lowest priority queue.
There are two ways of determining how traffic in queues is handled, Strict Priority 
and Weighted...

Quality of Service
Configuring QoS - General
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•Queue—Displays the queue number.
•Scheduling Method: Select one of the following options:
-
Strict Priority—Traffic scheduling for the selected queue and all higher 
queues is based strictly on the queue priority.
-
WRR—Traffic scheduling for the selected queue is based on WRR. The 
period time is divided between the WRR queues that are not empty,...

Quality of Service
Configuring QoS - General
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By changing the CoS/802.1p to Queue mapping (CoS/802.1p to Queue) and the 
Queue schedule method and bandwidth allocation (Queue page), it is possible to 
achieve the desired quality of service in a network.
The CoS/802.1p to Queue mapping is applicable only if one of the following exists:
•The device is in QoS Basic mode and CoS/802.1p trusted mode...

Quality of Service
Configuring QoS - General
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Mapping DSCP to Queue
The DSCP (IP Differentiated Services Code Point) to Queue page maps DSCP 
values to egress queues. The DSCP to Queue Table determines the egress 
queues of the incoming IP packets based on their DSCP values. The original VPT 
(VLAN Priority Tag) of the packet is unchanged.
By simply changing the DSCP to Queue mapping and the Queue...

Quality of Service
Configuring QoS - General
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The following tables describe the default DSCP to queue mapping for a 4-queue 
system:
To  m a p  D S C P  t o  q u e u e s :
STEP 1Click Quality of Service > General > DSCP to Queue.
The DSCP to Queue page contains Ingress DSCP. It displays the DSCP value in 
the incoming packet and its associated class. 
STEP  2Select the Output Queue (traffic...

Quality of Service
Configuring QoS - General
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Configuring Bandwidth
The Bandwidth page enables users to define two values, Ingress Rate Limit and 
Egress Shaping Rate, which determine how much traffic the system can receive 
and send. 
The ingress rate limit is the number of bits per second that can be received from 
the ingress interface. Excess bandwidth above this limit is discarded. 
The...

Quality of Service
Configuring QoS - General
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•Committed Information Rate (CIR)—Enter the maximum bandwidth for the 
egress interface. 
•Egress Committed Burst Size (CBS)—Enter the maximum burst size of data 
for the egress interface in bytes of data. This amount can be sent even if it 
temporarily increases the bandwidth beyond the allowed limit.
STEP  5Click Apply. The bandwidth settings are...

Quality of Service
Configuring QoS - General
501 Cisco Small Business 200, 300 and 500 Series Managed Switch Administration Guide (Internal Version) 
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•Committed Burst Size (CBS)—Enter the maximum burst size (CBS) in bytes. 
CBS is the maximum burst of data allowed to be sent even if a burst exceeds 
CIR.
STEP  6Click Apply. The bandwidth settings are written to the Running Configuration file.
VLAN Ingress Rate Limit 
NOTEThe VLAN Rate Limit feature is not available when the device is in Layer 3 mode....

Quality of Service
QoS Basic Mode
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•Committed Burst Size (CBS)—Enter the maximum burst size of data for the 
egress interface in bytes of data. This amount can be sent even if it 
temporarily increases the bandwidth beyond the allowed limit. Cannot be 
entered for LAGs.
STEP  4Click Apply. The VLAN rate limit is added, and the Running Configuration file is 
updated.
TCP Congestion Avoidance
The...