System Administration Guide: IP Services

How to Configure the IPQoS Configuration File for an Application Server

Log in to the IPQoS-enabled application server, and create a new IPQoS configuration file with a .qos extension.
For example, you would create the /var/ipqos/BigAPPS.qos file for the application server. Begin with the following required phrases to start the action statement that invokes the ipgpc classifier:
fmt_version 1.0 action { module ipgpc name ipgpc.classify params { global_stats TRUE }
For an explanation of the opening action statement, refer to How to Create the IPQoS Configuration File and Define Traffic Classes.

Create classes to select traffic from three applications on the BigAPPS server.

Add the class definitions after the opening action statement.

    class {
        name smtp
        enable_stats FALSE
        next_action markAF13
    }
    class {
        name news
        next_action markAF21
    }
    class {
        name ftp
        enable_stats TRUE
        next_action meterftp
    }

`name smtp`	Creates a class that is called `smtp`, which includes email traffic flows to be handled by the SMTP application
`enable_stats FALSE`	Enables statistics collection for the `smtp` class. However, because the value of `enable_stats` is `FALSE`, statistics for this class are not taken.
`next_action markAF13`	Instructs the `ipgpc` module to pass packets of the `smtp` class to the `markAF13` `action` statement after `ipgpc` completes processing.
`name news`	Creates a class that is called `news`, which includes network news traffic flows to be handled by the NNTP application.
`next_action markAF21`	Instructs the `ipgpc` module to pass packets of the `news` class to the `markAF21` action statement after `ipgpc` completes processing.
`name ftp`	Creates a class that is called `ftp`, which handles outgoing traffic that is handled by the FTP application.
`enable_stats TRUE`	Enables statistics collection for the `ftp` class.
`next_action meterftp`	Instructs the `ipgpc` module to pass packets of the `ftp` class to the `meterftp` `action` statement after `ipgpc` completes processing.

For more information about defining classes, refer to How to Create the IPQoS Configuration File and Define Traffic Classes.

Define filter clauses to select traffic of the classes defined in Step 2.

    filter {
        name smtpout
        sport smtp
        class smtp
    }
    filter {
        name newsout
        sport nntp
        class news
    }
        filter {
        name ftpout
        sport ftp
        class ftp
    }
        filter {
        name ftpdata
        sport ftp-data
        class ftp
    }
}

`name smtpout`	Gives the name `smtpout` to the filter.
`sport smtp`	Selects traffic with a source port of 25, the well-known port for the `sendmail` (SMTP) application.
`class smtp`	Identifies the class to which the filter belongs, in this instance, class `smtp`.
`name newsout`	Gives the name `newsout` to the filter.
`sport nntp`	Selects traffic with a source port name of `nntp`, the well-known port name for the network news (NNTP) application.
`class news`	Identifies the class to which the filter belongs, in this instance, class `news`.
`name ftpout`	Gives the name `ftpout` to the filter.
`sport ftp`	Selects control data with a source port of 21, the well-known port number for FTP traffic.
`name ftpdata`	Gives the name `ftpdata` to the filter.
`sport ftp-data`	Selects traffic with a source port of 20, the well-known port number for FTP data traffic.
`class ftp`	Identifies the class to which the `ftpout` and `ftpdata` filters belong, in this instance `ftp`.

How to Configure Forwarding for Application Traffic in the IPQoS Configuration File

The next procedure shows how to configure forwarding for application traffic. In the procedure, you define per-hop behaviors for application traffic classes that might have lower precedence than other traffic on a network. The steps continue building the /var/ipqos/BigAPPS.qos file in Example 34-3.

Before You Begin

The procedure assumes that you have an existing IPQoS configuration file with already-defined classes and already-defined filters for the applications to be marked.

Open the IPQoS configuration file that you have created for the application server, and locate the end of the last filter clause.
In the /var/ipqos/BigAPPS.qos file, the last filter is the following:
filter { name ftpdata sport ftp-data class ftp } }

Invoke the marker as follows:
action { module dscpmk name markAF13
module dscpmk
Invokes the marker module dscpmk.

name markAF13
Gives the name markAF13 to the action statement.

Define the per-hop behavior to be marked on electronic mail traffic flows.

    params {
        global_stats FALSE
        dscp_map{0-63:14}
        next_action continue
    }
}

`global_stats FALSE`	Enables statistics collection for the `markAF13` marker `action` statement. However, because the value of `enable_stats` is `FALSE`, statistics are not collected.
`dscp_map{0-63:14}`	Assigns a DSCP of `14` to the packet headers of the traffic class `smtp`, which is currently being processed by the marker.
	`next_action continue`	Indicates that no further processing is required on packets of the traffic class `smtp`. These packets can then return to the network stream.

The DSCP of 14 tells the marker to set all entries in the dscp map to the decimal value 14 (binary 001110). The DSCP of 14 sets the AF13 per-hop behavior. The marker marks packets of the smtp traffic class with the DSCP of 14 in the DS field.

AF13 assigns all packets with a DSCP of 14 to a high-drop precedence. However, because AF13 also assures a Class 1 priority, the router still guarantees outgoing email traffic a high priority in its queue. For a table of possible AF codepoints, refer to Table 37-2.

Add a marker action statement to define a per-hop behavior for network news traffic:
action { module dscpmk name markAF21 params { global_stats FALSE dscp_map{0-63:18} next_action continue } }
name markAF21
Gives the name markAF21 to the action statement.

dscp_map{0-63:18}
Assigns a DSCP of 18 to the packet headers of the traffic class nntp, which is currently being processed by the marker.

The DSCP of 18 tells the marker to set all entries in the dscp map to the decimal value 18 (binary 010010). The DSCP of 18 sets the AF21 per-hop behavior. The marker marks packets of the news traffic class with the DSCP of 18 in the DS field.

AF21 assures that all packets with a DSCP of 18 receive a low-drop precedence, but with only Class 2 priority. Thus, the possibility of network news traffic being dropped is low.

How to Configure the IPQoS Configuration File for an Application Server

See Also

How to Configure Forwarding for Application Traffic in the IPQoS Configuration File

Before You Begin

See Also