Subject: Re: '::' address as destination

From: Tim Hartrick <[email-masked]>
Date: Thu, 27 Dec 2001 11:20:46 -0800 (PST)

Lilian,

> 
> RFC 2373 states that:
> "The unspecified address must not be used as the destination address
>  of IPv6 packets or in IPv6 Routing Headers."
> 
> However it seems that certain stacks are using this address in a different
> way.
> 
> When '::' is the destination address:
> - some use the first available interface's address
> - some use the loopback address
> 
> Is there a chance that one of these will become the acceptable norm? It
> would be interesting to know if the majority of implementations actually
> return an error for this case.
> 

The convention used by BSD for IPv4 was to map INADDR_ANY to the address
of the first available interface.  At least that is what I see in the 4.4
BSD lite source for in_pcbconnect.  I assume that both of the above described
IPv6 behaviors are an attempt to emulate this IPv4 behavior.

I see little upside in attempting to standardize this behavior since no
fielded implementation will be able to change regardless of what behavior
is standardized.

tim
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