SUMMARY: Broadcast address on 4.1.4 and solaris 2.x

From: Tony C. Wu (
Date: Wed Oct 15 1997 - 09:46:27 CDT

The answer is yes, changing broadcast address to all ones won't kill

Thanks to:

Casper Dik <casper@holland.Sun.COM>
Singh Adrian <>
Frank Pardo <>

Frank Pardo's very detailed answer as well as the original questions are

>From Wed Oct 15 22:39:38 1997
Date: Wed, 15 Oct 1997 09:34:55 -0400 (EDT)
From: Frank Pardo <>
Subject: Re: Broadcast address on 4.1.4 and solaris 2.x

> From Wed Oct 15 04:44 EDT 1997
> Date: Wed, 15 Oct 1997 15:57:03 +0800 (CST)
> From: "Tony C. Wu" <>
> X-Sender: tonywu@micro
> To:
> Subject: Broadcast address on 4.1.4 and solaris 2.x
> MIME-Version: 1.0
> Hello there,
> We have a mixed network of sparcs running both 4.1.4 and solaris 2.x
> They are on the same class C subnet. The last number of broadcast address
> on solaris 2.x is 255 (0xff), however, in sunos 4.1.4 it's 0 (0x00). And I
> just found a mysterious problem that sometimes solaris 2.x's network dies
> without any error messages. I believe it has something to do with the
> broadcast address, coz we have the same problem on a linux box which's
> connected to the same subnet and using 255 as the broadcast address too.
> So, Can we safely change SunOS 4.1.4's broadcast to 255 (0xff) without
> breaking any Sun's special services, such as NIS, some sort of RPC ?
> Can anybody explain why sunos 4.1.4 uses 0 (0x00) as the broadcast address
> ?
> Thanks,
> Tony C. Wu

The history: SunOS is based on BSD, and the original BSD implementation
of IP used all-zeroes for broadcasting. Solaris is based on SysV, which
used/uses all-ones for broadcasting.

What you should do: Configure all your SunOS machines to use all-ones.
All-ones is the standard nowadays; all-zeroes is obsolete.

Using all-ones on SunOS is perfectly safe. In several previous jobs, I
worked with mixed networks that included SunOS, and the SunOS machines
were always configured to use all-ones for broadcast addresses, to make
them compatible with Solaris, AIX, HP-UX, Linux, etc. Everything worked
just fine that way.

  Frank Pardo  <>
  Transaction Information Systems
  New York City

Chi fila ha una camicia e chi non fila ne ha due. -- Italian proverb

-- Tony C. Wu

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