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SMCD3GN2 Wireless Cable Modem User Manual

CoS Settings Menu

Given that there will always be points in the network where multiple traffic streams merge or

where network links will change speed and capacity, it is important to move traffic on the

basis of relative importance. Without CoS prioritization, less important traffic can consume

network bandwidth and slow down or halt the delivery of more important traffic. For example,

without CoS, most traffic received by the Gateway is forwarded with the same priority it had

upon entering the Gateway. In many cases, such traffic is ‘‘normal’’ priority and competes for

bandwidth with all other normal-priority traffic, regardless of its relative importance to your

requirements. CoS helps to keep the most important network traffic moving at an acceptable

speed, regardless of current bandwidth usage. This means you can manage available

bandwidth so that the switch transmits the most important traffic first.

The CoS Settings menu lets you configure a CoS priority of 0 through 7 for an outbound

packet. When the packet is then sent to a port, the CoS priority determines which outbound

queue the packet uses. After configuring CoS priority for outbound packets, use this menu to

map the classes of service to the Gateway’s four ports.

To access the CoS Settings menu, click

QOS

in the menu bar and then click the

CoS

submenu in the menu bar. Figure 25 shows an example of the menu.

Note:

The

COS

submenu is not available in the menu bar if

Enable QOS Module

is not

checked in the QoS Settings menu (see page 39).

Figure 25. CoS Settings Menu

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47

SMCD3GN2 Wireless Cable Modem User Manual

To define CoS settings:

1. Check

Enable QoS Class based on CoS

.

2. For each class of service, assign a queue number from 0 to 3. Higher priority values are

evaluated as being of higher importance than lower priority values.

3. Under

Port Default CoS

, map the Gateway’s four ports to the classes of service you

defined in the previous step.

–

CoS setting from 0 to 3 = normal priority. Packets in this queue leave the port after

the high-priority queue is emptied.

–

CoS setting from 4 to 7 = high priority. Packets in this queue leave the port first.

4. Click

Apply

.

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SMCD3GN2 Wireless Cable Modem User Manual

DSCP Based QoS Menu

The DSCP Based QoS menu lets you classify and prioritize traffic using DSCP tags. DSCP

allows the Gateway to determine how traffic classes should be prioritized. Using the DSCP

Based QoS menu, you can use DSCP to provide different levels of service to conforming

and non-conforming traffic by appropriately selecting the DSCP values in this menu. The

Gateway uses the Hierarchical Token Bucket queuing algorithm, which divides the 64

possible DSCP code values into 8 queues.

Table 7 shows the actual queuing.

Table 7. Queuing for DSCP-Based QoS

Name

Precedence

DSCP Range

Priority

Routing (default)

000 (0)

000000(0) – 000111 (7)

8

Priority

001 (1)

001000 (8) – 001111 (15)

7

Immediate

010 (2)

010000 (16) – 010111 (23)

6

Flash

011 (3)

011000 (24) – 011111 (31)

5

Flash Override

100 (4)

100000 (32) – 100111 (39)

4

Critical

101 (5)

101000 (40) – 101111 (47)

3

Internetwork Control

110 (6)

111000 (48) – 110111 (55)

2

Network Control

111 (7)

111000 (56) – 111111 (63

1

To access the DSCP Based QoS menu, click

QOS

in the menu bar and then click the

DSCP

submenu in the menu bar. Figure 26 shows an example of the menu.

Note:

The

DSCP

submenu is not available in the menu bar if

Enable QOS Module

is not

checked in the QoS Settings menu (see page 39).

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SMCD3GN2 Wireless Cable Modem User Manual

Figure 26. DSCP Based QoS Menu

To define DSCP-based QoS settings:

1. Check

Enable DHCP Based QoS

.

2. For each index, enter a DSCP value from 0 to 63.

3. Under

Queue

, select a queue (from 0 to 3) you want to map to this DSCP value. Higher

priority values are evaluated as being of higher importance than lower priority values.

4. To define DSCP-based QoS values for other queues, repeat steps 2 and 3.

5. Click

Apply

.

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SMCD3GN2 Wireless Cable Modem User Manual

Queue Settings Menu

The Queue Settings menu lets you configure QoS behavior as either strict priority or

weighted priority.

y

Strict priority – allows delay-sensitive data such as voice to be sent before packets in

other queues.

y

Weighted priority – lets you assign each queue with a certain weight indicating the

amount of guaranteed capacity, with high priority packets served before any low priority

packets.

To access the Queue Settings menu, click

QOS

in the menu bar and then click the

Queue

submenu in the menu bar. Figure 27 shows an example of the menu.

Note:

The

Queue

submenu is not available in the menu bar if

Enable QOS Module

is not

checked in the QoS Settings menu (see page 39).

Figure 27. Queue Settings Menu