How to Add and Delete Persistant Routes in AIX

Chatter-phone-300x234Wow, AIX does not like to make anything easy. Nor do they like to make things intuitive. Need to remove a route from AIX, well get ready to have one command to temporariliy remove a route and another command to remove the route for good. Same goes with adding a route. "Quit your bitching, and use Smitty", you say? Well smitty does not make anything any easier, especially since the UI likes to show you fields that you does not necessarily need you to use. Oh, plus they let you type in them. Asking me for a netmask when adding a static route does not seem like a crazy request to me? But jokes on you, you were not supposed to type anything there.

Anyway, I was tasked with cleaning up a few bad routes that were added to a handful of servers. Note that I was not interested in adding the routes temporarily before I added them as persistent routes. These were simple one liners that I felt very comfortable adding to the ODM right out the gate.

So first we need to check the ODM for the routes that we need to remove. In this example we want to delete the route fro, so lets find just that route. Note all of these are host routes.

# lsattr -El inet0 | grep
route host,-hopcount,0,,-if,en1,,,,-static,, Route True


Now lets delete the route above

# chdev -l inet0 -a delroute=,


We have a second route to delete so lets kill that one too

# chdev -l inet0 -a delroute=,


Now lets add the correct routes – the format is as shown below

chdev -l inet0 -a route=host,-hopcount,1,-netmask,netmask,network,gateway


Now on a few of the servers I was working on I had to remove network routes as well as host routes. You need to know that the syntax is anoyingly different adding network routes. In the example below I first need to remove the network route.

chdev -l inet0 -a delroute="net,-hopcount,0,,,,,,-static,,"


Now lets add our new and correct route

chdev -l inet0 -a route="host,-hopcount,0,,,,,,-static,,"

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How to Configure NTP in a RHEL/CentOS Vmware Guest

HourglassSuccessful time keeping in a Virtual Machine can be a bit confusing. At times I have been told to use Vmware Tools to sync time between the Guest and the Host, and at time I have been advised to avoid this functionality and use NTP. The following information is direct from a VMware KB article (updated, 4/16/2010) so I am going to follow their lead on this and use NTP exclusively.

First off VMware advises using the NTP service to keep time in sync, but it suggests
using an additional kernel parameter that you add to your grub.conf. See the KB Article for more info on how to do this.

  • notsc for RHEL/Centos 4.6 64bit
  • notsc divider=10 forĀ  RHEL/Centos 5.3 64bit

Note that there are no additional params needed for 5.4

Also, inside the ntp.conf the following line should be added to the top of the file.

tinker panic 0

This configuration directive instructs NTP not to give up
if it sees a large jump in time. This is important for coping with large
time drifts and also resuming virtual machines from their suspended state.

It is also important not to use the local clock as a time source, often
referred to as the Undisciplined Local Clock. NTP has a tendency to fall
back to this in preference to the remote servers when there is a large
amount of time drift.

An example of such a configuration is below. You should comment out both


fudge stratum 10

Also, if you are using ntp, you want to make sure that you disable
Vmware tools time sync. You can do so with the following command via the
guest OS.

vmware-guestd –cmd “vmx.set_option synctime 1 0”