Subject: Re: ADMIN: Final warning to John Stanley

From: John Stanley <[email-masked]>
Date: Wed, 14 Sep 2005 11:33:45 -0700 (PDT)

"Charles Lindsey" <chl@xxxxxxxxxxxxxxxx>:

>_You_ know that the proposed syntax is a nonsense, and _I_ know that the
>proposed syntax is a nonsense. But the WG has voted against us.

The only "vote" I know of regarding this was one that asked:

YES - IP addresses should be allowed as path-identity.
NO - IP addresses should not be allowed as path-identity.

I've seen no vote on the syntax you produced. Is the archive incomplete?
Did we actually vote to approve ambiguous syntax for poorly defined header 
contents? I mean, did we actually vote to approve THIS specific ...

>Yes, but I believe that using a non-standard notation for IPv6 addresses
>is a worse evil than putting up with the minor inconvenience of the
>dead:beef problem (which is most unlikely to arise in practice, and is
>easily worked around by any sysadmin who gets caught by it).
 
It is not "evil" to use a simple notation. It thus is not a "worse evil".
It is something that admins won't notice in most cases, since they won't
be entering the information, it will be entered by the software
automatically, IF it even applies to their site. (The vast majority of
admins will never deal with it AT ALL.) And "easily worked around"  
requires renaming one's site, after noticing that there is a problem. A
problem which may have flooded your communications line already. 

What is evil is to deliberately write a known interoperability issue into 
the standard when the solution is trivial. Our first goal used to be 
interoperability, and the first goal of Path used to be to prevent loops. 
This abandons both.

I'm sorry, but if I didn't respond to your objection again, the Chair 
would use it as an example of non-constructive "failure to respond".

---

From: Richard Clayton <[email-masked]>
Date: Wed, 14 Sep 2005 22:31:12 +0100

In message <[email-masked]>, John
Stanley <[email-masked]> writes

>problem which may have flooded your communications line already. 

I don't follow that

If your site is called "beef" and someone puts an IPv6 address into the
Path header field with a :beef: component then until you notice, you
will get less traffic rather than more (assuming all of your peers are
treating ":" as a delimiter).  How does a flood occur ?

- -- 
richard                                              Richard Clayton

They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety.         Benjamin Franklin

---

From: Richard Clayton <[email-masked]>
Date: Thu, 15 Sep 2005 11:13:07 +0100

In message <[email-masked]>, Richard Clayton
<[email-masked]> writes
>treating ":" as a delimiter).  How does a flood occur ?

John replied to my question, but since we won't see that answer for two
weeks I shall paraphrase it here by replying to myself (sorry!).

His scenario was that a site had decided to use an IPv6 address as its
identity and was unlucky enough to be have components of that IP address
which were, for example, :dead:beef:

Now if that site's peers parse this as the two barewords "dead" and
"beef" then they won't realise that an article has already passed
through the site and so they will send it there again. John thinks that
this will "flood" the comms link.

However, I don't think that's quite true, since in practice (AIUI) the
site will be offered the article (IHAVE, CHECK etc) and will refuse it
based on the message-ID. So there will be extra traffic, but not all
that much (and given the wide range of similar speed paths through the
Internet it should be quite used to having multiple peers all offering
it the same article)

If the traffic _was_ a problem then the fix would be to not use the IPv6
address as an entity (we don't encourage that anyway) or to negotiate
with all its direct peers (the only people who matter for this second
scenario) to arrange that they don't treat ":" as a delimiter.

Going back to the first scenario (where peers don't hand over articles
that have passed through a site with an IPv6 :dead:beef: type of
identity) then the best fix (since presumably they have good reasons for
wishing to still be called "beef") is once again to negotiate with peers
to ask them to fix their view of delimiters. Note that in this case the
flood-fill nature of propagation means that _only_one_peer_ has to fix
their software.  

John pointed out (in the message we haven't seen on the list) that
detecting missing articles wasn't trivial -- and that, in my view, is a
valid point to make; newsadmins aren't going to spending their days
checking for completeness, a problem may go overlooked for months.

However, since at present no-one is called "beef" (or similar); since
flood-fill is a very robust distribution system; and since we indicate
that this is essentially a legacy form of recording identity, this is
all pretty moot.

Bottom line for me is that though this is a theoretical problem, it is
not now, or will ever be a practical one.

- -- 
richard                                              Richard Clayton