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Date:      Thu, 23 Oct 2003 15:39:53 -0400
From:      Charles Swiger <cswiger@mac.com>
To:        net@freebsd.org
Subject:   Re: Help Broadcasting a UDP packet on the LAN:URGENT
Message-ID:  <ACAAF2C8-0590-11D8-92E1-003065ABFD92@mac.com>
In-Reply-To: <200310231145.04241.wes@softweyr.com>

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On Thursday, October 23, 2003, at 02:45 PM, Wes Peters wrote:
>> The all-ones broadcast is supposed to go to all physically connected
>> network segments, regardless of whether a particular interface is
>> ifconfig'ured with an IP that is part of a particular layer-3 subnet.
>> You should be able to send the broadcast packet out from an interface
>> which is up but does not have an IPv4 address assigned, right?
>
> So long as it IS configured with the IPv4 protocol, I'd say yes.  Ditto
> for VLANs.

Agreed.

Some switches use a VLAN tag of 0 to indicate a "default VLAN", so it 
perhaps might be reasonable to select that rather than all of the 
logical VLAN interfaces configured against a physical parent interface. 
  However, if the capability of choosing which interfaces should 
participate in the "all ones group" is already in Bruce's code, then 
that same mechanism could also be used to manage which VLAN interfaces 
get used.

Also, Barney's comments here:

> On point-to-point, I've never been really happy that the two ends can
> have addresses in different nets, but some people do it that way.
> I always prefered to define a /30 (or /31 if the code allows) for the
> link itself.  But that difference solves the issue of whether the p2p
> link should be treated as local or not - if the far end is on a
> different subnet, it's remote; same subnet, it's local.

...make sense to me as well, for whatever that may be worth....  :-)

Take care,

-- 
-Chuck



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