Perform this task to enable a VRF interface to be configured as the source interface when syslog messages are been exported to a VRF host.

In the following example, a VRF interface is configured as the source interface when sending syslog messages to a VRF host:

Device> enable
Device# configure terminal
Device(config)# logging source-interface ethernet 0 vrf1 
Device(config)# end
Device> show running interface loopback 49
Device> show running | include logging
Device# show running interface loopback 49

             Building configuration...
             Current configuration : 84 bytes
             !
             interface Loopback49
              ip vrf forwarding vrf1
              ip address 10.4.2.39 255.0.0.0
             end
Device# show running | includes logging
      logging source-interface Loopback49 vrf1
      logging host 192.0.2.1 vrf1

The logging source-interface CLI command can be used to specify a source IP address in all syslog packets sent from the device. The following syslog filter module example demonstrates the use of show CLI commands (show running-config and show ip interface in this case) within a filter module to add the source IP address to syslog messages. The script looks for the local namespace variable "source_ip::init" first. If the variable is not defined in the first syslog message processed, the filter will run the show commands and use regular expressions to get the source interface and then its IP address.

Note that in this script the show commands are run only once. If the source interface or its IP address were to be changed, the filter would have to be reinitialized to pick up the new information. (You could have the show commands run on every syslog message, but this practice would not scale very well.)

#  ===================================================================
#  Embedded Syslog Manager                           ||        ||
#                                                    ||        ||
#  Source IP Module                                 ||||      ||||
#                                               ..:||||||:..:||||||:..
#                                             ------------------------
#                                              C i s c o  S y s t e m s 
#   ===================================================================
# Usage: Adds Logging Source Interface IP address to all messages.
#
# Namespace:source_ip
#
#  ======================= End User Setup ==============================
namespace eval ::source_ip {
    if { [info exists init] == 0 } {
       if { [catch {regexp {^logging source-interface (.*$)} [exec show
run | inc logging source-interface] match source_int}]} {
           set suffix "No source interface specified"
       } elseif { [catch {regexp {Internet address is (.*)/.*$} [exec
show ip int $source_int | inc Internet] match ip_addr}]} {
           set suffix "No IP address configured for source interface"
       } else {
           set suffix $ip_addr
       }
       set init 1
    }
 
    if { [string length $::orig_msg] == 0} {
      return ""
    }
    return "$::orig_msg - $suffix"
} ;# end namespace source_ip