(usagi-users 01205) Re: Is this a bug?

[JINMEI Tatuya / 神明達哉 <jinmei@xxxxxxxxxxxxxxxxxxxxx>]

>>>>> On Thu, 24 Jan 2002 16:50:02 +0200 (EET), 
>>>>> Pekka Savola <pekkas@xxxxxxxxxx> said:

>> It is not clear enough which one should be preferred in the following
>> situation:
>> against a global destination address,
>> A: a link-local address on the outgoing interface (assuming that the
>> interface does not have a larger-scope address)
>> B: a global address on another interface
>> 
>> according to the address selection draft, we'll choose B.  And I think
>> it is a reasonable decision, or at least not a "very bad" choice.

> How badly would you have to much up your routes to get into this 
> situation?  How many *real* (non-erroneous) usage scenarios are there?

Not so many, but not so rare.  Some administrators tend to configure
a well-known address on a loop-back interface and prefer to use the
well-known address as the source address.  (and in some cases the
well-known server has no other global addresses.)  In such a case, the
source address tends to be chosen on a different interface than the
packet's outgoing one.

I'd not say that this is typical.  But, anyway, my point is that this
is rather an operational issue (not an implementation's bug).  If you
configure enough addresses on every interface and the implementation
still chooses the source address on a non-outgoing interface (without
any reasonable reasons like above), I agree it is likely an
implementation's bug.

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					jinmei@xxxxxxxxxxxxxxxxxxxxx