Creating an IPQoS Configuration File for an Application Server

This section explains how to create a configuration file for an application server that provides major applications to customers. The procedure uses as its example the BigAPPS server from Figure 33-4.

The following configuration file defines IPQoS activities for the BigAPPS server. This server hosts FTP, electronic mail (SMTP), and network news (NNTP) for customers.

Example 34-3 Sample IPQoS Configuration File for an Application Server

fmt_version 1.0

action {
    module ipgpc
    name ipgpc.classify
    params {
        global_stats TRUE
    }
    class {
        name smtp
        enable_stats FALSE
        next_action markAF13
    }
    class {
        name news
        next_action markAF21
    }
    class {
        name ftp
        next_action meterftp
    }
    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
    }
}
action {
    module dscpmk
    name markAF13
    params {
        global_stats FALSE
        dscp_map{0-63:14}
        next_action continue
    }
}
action {
    module dscpmk
    name markAF21
    params {
        global_stats FALSE
        dscp_map{0-63:18}
        next_action continue
    }
}
action {
    module tokenmt
    name meterftp
    params {
        committed_rate 50000000
        committed_burst 50000000
        red_action_name AF31
        green_action_name markAF22
        global_stats TRUE
    }
}
action {
    module dscpmk
    name markAF31
    params {
        global_stats TRUE
        dscp_map{0-63:26}
        next_action continue
    }
}
action {
    module dscpmk
    name markAF22
    params {
        global_stats TRUE
        dscp_map{0-63:20}
        next_action continue
    }
}

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 Flow Control in the IPQoS Configuration File

To control the rate at which a particular traffic flow is released onto the network, you must define parameters for the meter. You can use either of the two meter modules, tokenmt or tswtclmt, in the IPQoS configuration file.

The next procedure continues to build the IPQoS configuration file for the application server in Example 34-3. In the procedure, you configure not only the meter but also two marker actions that are called within the meter action statement.

Before You Begin

The steps assume that you have already defined a class and a filter for the application to be flow-controlled.

Open the IPQoS configuration file that you have created for the applications server.
In the /var/ipqos/BigAPPS.qos file, you begin after the following marker action:
```
action {
    module dscpmk
    name markAF21
    params {
        global_stats FALSE
        dscp_map{0-63:18}
        next_action continue
    }
}
```
Create a meter action statement to flow-control traffic of the ftp class.
```
action { module tokenmt name meterftp         
```
module tokenmt

Invokes thetokenmt meter.

name meterftp

Gives the name meterftp to the action statement.
Add parameters to configure the meter's rate.
```
params { committed_rate 50000000 committed_burst 50000000 
```
committed_rate 50000000

Assigns a transmission rate of 50,000,000 bps to traffic of the ftp class.

committed_burst 50000000

Commits a burst size of 50,000,000 bits to traffic of the ftp class.

For an explanation of tokenmt parameters, refer to Configuring tokenmt as a Two-Rate Meter.
Add parameters to configure traffic conformance precedences:
```
 red_action markAF31 green_action_name markAF22 global_stats TRUE } }
```
red_action_name markAF31

Indicates that when the traffic flow of the ftp class exceeds the committed rate, packets are sent to the markAF31 marker action statement.

green_action_name markAF22

Indicates that when traffic flows of class ftp conform to the committed rate, packets are sent to the markAF22 action statement.

global_stats TRUE

Enables metering statistics for the ftp class.

For more information about traffic conformance, see Meter Module.
Add a marker action statement to assign a per-hop behavior to nonconformant traffic flows of class ftp.
```
action { module dscpmk name markAF31 params { global_stats TRUE dscp_map{0-63:26} next_action continue } }
```
module dscpmk

Invokes the marker module dscpmk.

name markAF31

Gives the name markAF31 to the action statement.

global_stats TRUE

Enables statistics for the ftp class.

dscp_map{0–63:26}

Assigns a DSCP of 26 to the packet headers of the traffic class ftp whenever this traffic exceeds the committed rate.

next_action continue

Indicates that no further processing is required on packets of the traffic class ftp. Then these packets can return to the network stream.

The DSCP of 26 instructs the marker to set all entries in the dscp map to the decimal value 26 (binary 011010). The DSCP of 26 sets the AF31 per-hop behavior. The marker marks packets of the ftp traffic class with the DSCP of 26 in the DS field.
AF31 assures that all packets with a DSCP of 26 receive a low-drop precedence, but with only Class 3 priority. Therefore, the possibility of nonconformant FTP traffic being dropped is low. For a table of possible AF codepoints, refer to Table 37-2.
Add a marker action statement to assign a per-hop behavior to ftp traffic flows that conform to the committed rate.
```
action { module dscpmk name markAF22 params { global_stats TRUE dscp_map{0-63:20} next_action continue } }
```
name markAF22

Gives the name markAF22 to the marker action.

dscp_map{0–63:20}

Assigns a DSCP of 20 to the packet headers of the traffic class ftp whenever ftp traffic conforms to its configured rate.

The DSCP of 20 tells the marker to set all entries in the dscp map to the decimal value 20 (binary 010100). The DSCP of 20 sets the AF22 per-hop behavior. The marker marks packets of the ftp traffic class with the DSCP of 20 in the DS field.
AF22 assures that all packets with a DSCP of 20 receive a medium-drop precedence with Class 2 priority. Therefore, conformant FTP traffic is assured a medium-drop precedence among flows that are simultaneously released by the IPQoS system. However, the router gives a higher forwarding priority to traffic classes with a Class 1 medium-drop precedence mark or higher. For a table of possible AF codepoints, refer to Table 37-2.
Add the DSCPs that you have created for the application server to the appropriate files on the Diffserv router.