Description of problem:

I'd like to run custom pre/post scripts for ifup and ifdown, to make
advanced network configuration with iproute and other tools.

Currently there is no way to execute custom scripts on ifup/ifdown for an ethernet interface. Default networking scripts look for /sbin/ifup-local, and execute it if it exists, but it would be much more convenient to have something under /etc/ instead, and be able to have a script per interface useable out-of-the-box without any manual hacks under /sbin/.

Version-Release number of selected component (if applicable):
rhel5

Currently in rhel5 you can do this:

1. create /etc/sysconfig/network-scripts/ifcfg-zscripts with contents
DEVICE=dummy0
ONBOOT=yes

2. create /sbin/ifup-local executable with for example:
#!/bin/bash
if [ "$1" == "dummy0" ]; then
  echo "running scripts"
 ip...
 arp...

fi

It will be executed for every interface, others that dummy0 are skipped.
But this is not very nice method..

Debian/Ubuntu allows the user to specify custom commands directly from /etc/network/interfaces file, configured per interface.