Quality of Service (QoS): Managing Bandwidth More Effectively

Preparation for Configuring QoS

2.Select the QoS option you want to use. Table 15-6lists the traffic types (QoS classifiers) and the QoS options you can use for prioritizing or setting a policy on these traffic types:

Table 15-6. Applying QoS Options to Traffic Types Defined by QoS Classifiers

QoS Options for Prioritizing Outbound Traffic

 

 

QoS Classifiers

 

 

 

 

 

UDP/

IP

IP-ToS

IP-

L3

VLAN

Source

 

 

TCP

Device

Precedence

DiffServ

Protocol

-ID

-Port

Option 1:

Prioritize traffic by sending specific

Yes

Yes

Yes 1

Yes

Yes

Yes

Yes

Set 802.1p

packet types (determined by QoS

 

 

 

 

 

 

 

Priority

classifier) to different outbound port

 

 

 

 

 

 

 

Only

queues on the switch.

 

 

 

 

 

 

 

 

Rely on tagged VLANs to carry

 

 

 

 

 

 

 

 

packet priority as an 802.1p value to

 

 

 

 

 

 

 

 

downstream devices.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Option 2:

Prioritize traffic by sending specific

Yes

Yes

No

Yes

No

Yes

Yes

Configure

packet types (determined by QoS

 

 

 

 

 

 

 

ToS DSCP

classifier) to different outbound port

 

 

 

 

 

 

 

Policy

queues on the switch.

 

 

 

 

 

 

 

with

Propagate a service policy by

 

 

 

 

 

 

 

802.1p

reconfiguring the DSCP in outbound

 

 

 

 

 

 

 

Priority

IP packets according to packet type.

 

 

 

 

 

 

 

 

(Assumes that downstream devices

 

 

 

 

 

 

 

 

can be configured to recognize the

 

 

 

 

 

 

 

 

DSCP in IP packets and implement

 

 

 

 

 

 

 

 

the service policy it indicates.)

 

 

 

 

 

 

 

 

Use tagged VLANs to carry packet

 

 

 

 

 

 

 

 

priority as an 802.1p value to

 

 

 

 

 

 

 

 

downstream devices.

 

 

 

 

 

 

 

1In this mode the configuration is fixed. You cannot change the automatic priority assignment when using IP-ToS Precedence as a QoS classifier.

3.If you want 802.1p priority settings to be included in outbound packets, ensure that tagged VLANs are configured on the appropriate links.

4.Determine the actual QoS configuration changes you will need to make on each QoS-capable device in your network in order to implement the desired policy. Also, if you want downstream devices to read and use DSCPs in IP packets from the switch, configure them to do so by enabling ToS Differentiated Service mode and making sure the same DSCP policies are configured.

N o t e

If you use TopTools for Hubs & Switches to configure QoS policy in a network,

 

it overrides any QoS settings configured through the CLI or the web browser

 

interface in any individual HP switch.

 

 

15-12