Summary: Urgent: Changing netmask without bringing down interface.

From: jason kappy <>
Date: Tue Apr 11 2006 - 12:22:50 EDT
This forum rocks. I got numerous replies and everyone suggested we can do it on fly. Thanks to everyone. I tested this on a test server and worked. However I was not permitted to do this on Prod. There was also recommendation to bring up a virutal interface and change netmask of that interface.
  ifconfig <interface> netmask
ifconfig ce0 x.x.x.x netmask x.x.x.x broadcast x.x.x.x  
   Here are couple of replies
  Hi Jason - if you really cannot down the interface try
"ifconfig netmask" (or whatever your netmask is)

then ping -s the broadcast for a bit "ping -s" (or 
you have, then see how you go.

Other than that, plumb in a virtual interface "ifconfig ceo:1" then 
configure with your settings and up this. When you have a scheduled 
reboot/downtime you can then set the netmask of your "main" interface 
    I can only speak from experience, I have reset netmask on the fly but it was usually because the netmask was wrong and there were connectivity problems and it didnt drop any connections. So when I changed and corrected it, things got better, not worst. From reading the man page on ifconfig, it doesnt seem to reset the port like the up or plumb/unplumb options. Make sure you put the right subnet netmask in /etc/netmasks so when you reboot you dont have the same problem.

  > Hi Gurus,
>                Is there any way to change netmask without bringing 
down the interface?
>   This what I did lastnight in mid of crises and later realized about 
>   .  
>   ifconfig ce0 plumb
>     ifconfig ce0 x.x.x.x up
>   As of now system communicates within the local network but not 
outside network. This is a Oracle databas box with Solaris 8.
>   Thanks,
>   J.

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Received on Tue Apr 11 12:23:19 2006

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