HP 4000M User Manual download pdf (Page 211)

6-135

Configuring the Switch

Class of Service (CoS): Managing Bandwidth More Effectively

Configuring the Switch

No Override. By default, the IP ToS, Protocol, and VLAN ID criteria auto-

matically list each of their options with

No override for priority. This means that

if you do not configure a priority for a specific option, CoS does not prioritize

packets to which that option applies. For example, if you do not specify a

priority for the IP protocol, then the IP protocol will not be a criteria for setting

a CoS priority. In this case, the packets will be handled as described above.

How To Configure CoS

You can use CoS regardless of whether your network has tagged VLANs. As

described earlier (under “Basic Operation” on page 6-132):

■ Using CoS in a tagged VLAN environment controls both of the following:

• Outbound port queue: To which queue (high or normal) a packet

will be sent

• Outbound 802.1p priority: Enters a new 802.1p priority setting in

an outbound packet or retains the packet’s existing 802.1p setting.

This enables the packet to carry an 802.1p priority to the next down-

stream device.

■ Using CoS without a tagged VLAN environment affects only the outbound

port queue to which a packet is sent. (That is, it prioritizes traffic flow

within the switch.) However, without a tagged VLAN environment, an

outbound packet cannot carry an 802.1p priority setting to a downstream

device.

To configure CoS, use this procedure:

1. Determine the CoS policy you want to implement. This includes analyzing

the types of traffic flowing through your network and identifying one or

more traffic types to prioritize. In order of precedence, these are:

a. Device Priority—destination or source IP address (Note that destina-

tion has precedence over source. See Table 6-7.)

b. IP Type of Service

c. Protocol Priority

d. VLAN Priority (requires at least one tagged VLAN on the network)

e. Incoming 802.1p Priority (requires at least one tagged VLAN on the

network)

For more on how CoS operates with the above traffic types, see Table 6-

7. Priority Criteria and Precedence on page 6-134.)

2. If you want 802.1p priority settings to be included in outbound packets,

ensure that tagged VLANs are configured on the appropriate links. (See

“Supporting CoS with an 802.1Q Tagged VLAN Environment” on 6-151.)

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HP 4000M User Manual Page 211