Cisco Sg2008 Manual

							Quality of Service
Mapping DSCP Values to Queues
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NOTEIf you click Restore Defaults, the following mappings are applied to all interfaces.
Mapping DSCP Values to Queues
The priority of a packet arriving at an interface can be identified by the 
Differentiated Service Code Point (DSCP) value in an IP packet header. The IP 
DSCP field might contain any one of 64 values (0–63). You can use the DSCP to 
Queue page to map these values to the four egress queues. Queue 1 has the 
lowest priority and queue 4 has the highest priority.
DSCP mapping settings are applied globally to all ports. 
To map DSCP values to queues:
STEP 1Click Quality of Service > DSCP to Queue in the navigation window.
STEP  2For each Ingress DSCP value, select a queue from the Output Queue list. Queue 1 
has the lowest priority, and queue 4 has the highest priority.
STEP  3Click Apply. Your changes are saved to the Running Configuration.
IP Precedence Output Queue
01
11
22
33
43
54
63
73 
						

							Quality of Service
Defining Rate Limit Profiles
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NOTEIf you click Restore Defaults, the following mappings are applied to all interfaces.
Defining Rate Limit Profiles
The rate-limiting feature enables you to set a maximum incoming traffic rate for a 
port. When the data rate exceeds configured rate, the switch drops all further 
traffic from the port. Rate limits are applied per port.
To apply rate limits, you first use this page to create one or more rate limit profiles. 
Profiles specify the criteria that determines when the rate limit is exceeded. Then, 
you assign rate limit profiles to interfaces (see Applying Rate Limit Profiles to 
Interfaces).
To add an entry to the Rate limit Profile Table:
STEP 1Click Quality of Service > Rate Limit Profile in the navigation window.
STEP  2Click Add.
STEP  3Enter the parameters:
•Profile ID—Specify any number from 1 to 64 to identify the profile.
•CIR—Specify the committed information rate, which is the rate at which data 
is transmitted. The rate is averaged over a minimum time increment. The 
range is 64-1048576 Kbps.  DSCP Value Output Queue
00-07 1
08-15 1
16-23 2
24-31 3
32-39 3
40-47 4
48-55 3
56-63 3 
						

							Quality of Service
Applying Rate Limit Profiles to Interfaces
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•CBS—Specify a committed burst size, which is the guaranteed amount of 
bandwidth for bursty traffic on the port. The range is 4-16384 KB.
STEP  4Click Apply and then click Close. Your changes are saved to the Running 
Configuration.
Applying Rate Limit Profiles to Interfaces
If you have created one or more rate limit profiles, you can use this page to assign 
them to interfaces. See Defining Rate Limit Profiles for instructions on creating 
profiles.
To apply a rate limit profile to an interface.
STEP 1Click Quality of Service > Interface Rate Limit in the navigation window.
STEP  2Use the Interface Type list to display Ports or LAGs in the Interface Rate Limit 
Table.
STEP  3Select the interface to configure and click Edit.
STEP  4Add or remove a profile:
•To assign a profile to this interface, click the profile ID in the Available list, 
and then click the right-arrow button to move it to the Selected list . All 
profiles disappear from the Available list, since only one profile can be 
assigned to a port.
•To remove a profile, click the profile ID in the Selected list, and then click the 
left-arrow button to move it to the Available list. All profiles appear in the 
Selected list.
STEP  5Click Apply and then click Close. Your changes are saved to the Running 
Configuration. 
						

							Quality of Service
Tr a f f i c  S h a p i n g
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Traffic Shaping
You can use the Tr a f f i c  S h a p i n g page to smooth the packet output rate. You can 
configure the maximum output rate for each port and LAG, expressed as a 
percentage of bandwidth. When the traffic rate reaches this limit, excess packets 
are retained in a queue and then are scheduled for later transmission over 
increments of time. 
To configure traffic shaping on a port or LAG:
STEP 1Click Quality of Service > Traffic Shaping in the navigation window.
STEP  2Use the Interface Type menu to display Ports or LAGs in the Traffic Shaping 
Settings table.
STEP  3Select the interface to configure and click Edit.
STEP  4For the selected Port or LAG, enter the output rate limit as a percentage of the total 
bandwidth and click Apply.
STEP  5Repeat the previous step as needed to assign bandwidth utilization to other ports 
and LAGs.
STEP  6When you are finished, click Close. Your changes are saved to the Running 
Configuration. 
						

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