Event selection for Python processing

About this task

Events destined for Python processing are configured through a log ID that references a Python policy. The selection of the events are performed via a filter associated with this log ID. The remainder of the events destined for the same syslog server can bypass Python processing by redirecting them to a different log ID. The following example clarifies this point:

Procedure

Creating the Python policy:

Example

A:dut-a# configure python python-policy PyForLogEvents create  
*A:dut-a>config>python>py-policy$  
 [no] description    - Configure the description of this policy 
 [no] dhcp           - Configure scripts to handle dhcp messages jritter
 [no] dhcp6          - Configure scripts to handle dhcp6 messages 
 [no] diameter       - Configure scripts to handle diameter messages 
 [no] gtpv1-c        - Configure scripts to handle GTPv1-C messages 
 [no] gtpv2-c        - Configure scripts to handle GTPv2-C messages 
 [no] pppoe          - Configure scripts to handle PPPoE messages 
 [no] radius         - Configure scripts to handle RADIUS messages 
 [no] vsd            - Configure scripts to handle VSD messages 
 [no] syslog         - Configure a script to handle outgoing syslog messages 
*A:dut-a>config>python>py-policy$ syslog 
  - syslog script <name> 
  - no syslog 
<name> :[32 chars max]

The detailed Python policy description is described in the 7450 ESS, 7750 SR, and VSR Triple Play Service Delivery Architecture Guide, "Python Script Support for ESM".

Log filters identify the events that are subject to Python processing:

Example

A:dut-a>config>log# info 
----------------------------------------------
        filter 6 
            default-action drop
            entry 1 
                action forward  
                match
                    application eq "nat"
                    number eq 2012      
                exit 
            exit 
        exit 
        filter 7 
            default-action forward
            entry 1 
                action drop
                match
                    application eq "nat"
                    number eq 2012
                exit 
            exit 
        exit

Syslog destination:

Example

 syslog 1
            address 192.168.1.1
        exit

Applying Python syslog policy to selected events via filter 6:

Example

        log-id 33  Note: Process log events with id of 2012 with Python before 
sending them to syslog server.
            filter 6
            from main 
            to syslog 1
            python-policy "PyForLogEvents"
            no shutdown
        exit
        log-id 34  Note: Log events that are not processed by Python.
            filter 7
            from main 
            to syslog 1  
            no shutdown
        exit

What to do next

In the example above, the configuration-only event 2012 from application "nat" is sent to log-id 33. All other events are forwarded to the same syslog destination via log-id 34, without any modification. As a result, all events (modified via log-id 33 and unmodified via log-id 34) are sent to the syslog 1 destination.

This configuration may cause reordering of syslog messages at the syslog 1 destination because of slight delay of messages processed by Python.