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How to Define Filters in the QoS
Policy
Before You Begin
Before you can perform the next steps, you should have completed the procedure How to Define the Classes for Your QoS Policy.
Create at least one filter for each class in the QoS planning table that you created in How to Define the Classes for Your QoS Policy.
Consider creating separate filters for incoming and outgoing traffic for each class, where applicable. For example, add an ftp-in filter and an ftp-out filter to the QoS policy of an IPQoS-enabled FTP server. You then can define an appropriate direction selector in addition to the basic selectors.
Define at least one selector for each filter in a class.
Use the QoS planning table that was introduced in Table 33-1 to fill in filters for the classes you defined.
Example 33-1 Defining Filters for FTP Traffic
The next table shows how you would define a filter for outgoing FTP traffic.
Class | Priority | Filters | Selectors |
|---|---|---|---|
ftp-traffic | 4 | ftp-out | saddr 10.190.17.44 daddr 10.100.10.53 sport 21 direction LOCAL_OUT |
See Also
To define a flow-control scheme, refer to How to Plan Flow Control.
To define forwarding behaviors for flows as the flows return to the network stream, refer to How to Plan Forwarding Behavior.
To plan for flow accounting of certain types of traffic, refer to How to Plan for Flow Accounting.
To add more classes to the QoS policy, refer to How to Define the Classes for Your QoS Policy.
To add more filters to the QoS policy, refer to How to Define Filters in the QoS Policy.
How to Plan Flow Control
Flow control involves measuring traffic flow for a class and then releasing packets onto the network at a defined rate. When you plan flow control, you define parameters to be used by the IPQoS metering modules. The meters determine the rate at which traffic is released onto the network. For an introduction to the metering modules, see Meter (tokenmt and tswtclmt) Overview.
The next procedure assumes that you have defined filters and selectors, as described in How to Define Filters in the QoS Policy.
Determine the maximum bandwidth for your network.
Review any SLAs that are supported on your network. Identify customers and the type of service that is guaranteed to each customer.
To guarantee a certain level of service, you might need to meter certain traffic classes that are generated by the customer.
Review the list of classes that you created in How to Define the Classes for Your QoS Policy.
Determine if any classes other than those classes that are associated with SLAs need to be metered.
Suppose the IPQoS system runs an application that generates a high level of traffic. After you classify the application's traffic, meter the flows to control the rate at which the packets of the flow return to the network.
Note - Not all classes need to be metered. Remember this guideline as you review your list of classes.
Determine which filters in each class select traffic that needs flow control. Then, refine your list of classes that require metering.
Classes that have more than one filter might require metering for only one filter. Suppose that you define filters for incoming and outgoing traffic of a certain class. You might conclude that only traffic in one direction requires flow control.
Choose a meter module for each class to be flow controlled.
Add the module name to the meter column in your QoS planning table.
Add the rates for each class to be metered to the organizational table.
If you use the tokenmt module, you need to define the following rates in bits per second:
Committed rate
Peak rate
If these rates are sufficient to meter a particular class, you can define only the committed rate and the committed burst for tokenmt.
If needed, you can also define the following rates:
Committed burst
Peak burst
For a complete definition of tokenmt rates, refer to Configuring tokenmt as a Two-Rate Meter. You can also find more detailed information in the tokenmt(7ipp) man page.
If you use the tswtclmt module, you need to define the following rates in bits per second.
Committed rate
Peak rate
You can also define the window size in milliseconds. These rates are defined in tswtclmt Metering Module and in the twstclmt(7ipp) man page.
Add traffic conformance outcomes for the metered traffic.
The outcomes for both metering modules are green, red, and yellow. Add to your QoS organizational table the traffic conformance outcomes that apply to the rates you define. Outcomes for the meters are fully explained in Meter Module.
You need to determine what action should be taken on traffic that conforms, or does not conform, to the committed rate. Often, but not always, this action is to mark the packet header with a per-hop behavior. One acceptable action for green-level traffic could be to continue processing while traffic flows do not exceed the committed rate. Another action could be to drop packets of the class if flows exceed peak rate.
Example 33-2 Defining Meters
The next table shows meter entries for a class of email traffic. The network on which the IPQoS system is located has a total bandwidth of 100 Mbits/sec, or 10000000 bits per second. The QoS policy assigns a low priority to the email class. This class also receives best-effort forwarding behavior.
Class | Priority | Filter | Selector | Rate |
|---|---|---|---|---|
8 | mail_in | daddr10.50.50.5 dport imap direction LOCAL_IN |
| |
8 | mail_out | saddr10.50.50.5 sport imap direction LOCAL_OUT | meter=tokenmt committed rate=5000000 committed burst =5000000 peak rate =10000000 peak burst=1000000 green precedence=continue processing yellow precedence=mark yellow PHB red precedence=drop |
See Also
To define forwarding behaviors for flows as the packets return to the network stream, refer to How to Plan Forwarding Behavior.
To plan for flow accounting of certain types of traffic, refer to How to Plan for Flow Accounting.
To add more classes to the QoS policy, refer to How to Define the Classes for Your QoS Policy.
To add more filters to the QoS policy, refer to How to Define Filters in the QoS Policy.
To define another flow-control scheme, refer to How to Plan Flow Control.
To create an IPQoS configuration file, refer to How to Create the IPQoS Configuration File and Define Traffic Classes.