Subject: RE: [Ieprep] identification of packets

From: "King, Kimberly S." <[email-masked]>
Date: Thu, 5 Dec 2002 13:16:14 -0500

Janet asked:
>Is there a way for site A to mark "the traffic" (at
>whatever layer is most likely to work) so that it recognized as
>"emergency traffic" on both access links?  And for the traffic to 
>be given the Sprint "emergency treatment" at site A's access link and 
>Genuity's "emergency treatment" at site B, which might actually be 
>different treatments?"

>If it is possible, is it practical, and what are the drawbacks, and to
>whom?

>I am asking nothing from the ISP core, except to pass the "marking" 
>(so ToS bits won't work).  

Janet,

Thank you for asking such good questions.  I take it by your last statement
(so ToS bits won't work) that you recognize that you can't expect ToS bits
to remain unmodified as they pass over the Internet.  For example, many ISPs
will zero these bits out.

Note that you are asking for a form of multiple ISP QoS that has not been
deployed to date for some pretty serious business and technical reasons (see
http://www1.ietf.org/mail-archive/working-groups/ieprep/current/msg00832.htm
l).  

The only thing I can think of at this time that might be possible if you
could get the providers to agree to it would be to provide some kind of
secure tunnel between them.  The ISPs would continue to zero out ToS on all
incoming packets but it wouldn't matter because the emergency ones would be
marked accordingly within the tunnel.  

Here I'm assuming a secure tunnel between ISP X and ISP Y.  There would have
to be some way to figure out how to put emergency traffic and only emergency
traffic into that tunnel.  Traffic can be remarked according to local use
perhaps requiring ISP X and Y to share information.  They would have to
trust each other (gulp).  I suppose they could police it to somewhat limit
DoS.  

Drawbacks include complexity adds security risks (plus all the ones Ran
listed associated with complexity in an earlier email), the design isn't
scalable, nicely identifying and aggregating "emergency traffic" will
perhaps make it an easier target for attackers, the cost could well exceed
the price of simply buying bigger access pipes on these locations that are
already recognized to carry emergency traffic, and I'm sure there are lots
more.

Kimberly
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From: RJ Atkinson <[email-masked]>
Date: Fri, 6 Dec 2002 09:27:56 -0500

On Thursday, Dec 5, 2002, at 13:16 America/Montreal, King, Kimberly S. 
> trust each other (gulp).  I suppose they could police it to somewhat 

Another approach is to encrypt all traffic between sites A and B (good
security practice anyway), but use filters inside routers inside each
site to set appropriate IP ToS bits on the relevant packets.

> already recognized to carry emergency traffic, and I'm sure there are 

The above should also work.  It is more complex than the scenario I 
outlined
in email a moment ago (because it needs most of the stuff I outlined 
plus
an IPsec VPN box) -- but it provides site-to-site security (which is
probably strongly desirable anyway).

Ran

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From: Bill Woodcock <[email-masked]>
Date: Fri, 6 Dec 2002 21:39:58 -0800 (PST)

On Thu, 5 Dec 2002, King, Kimberly  S. wrote:
    > Note that you are asking for a form of multiple ISP QoS...

Not necessarily...  Janet managed to break the problem down into
bite-sized market-addressable pieces...  If A and B can each
independently negotiate market-priced services with their own ISPs, and
there doesn't need to be any unfunded many-to-many relationship between
the ISPs themselves to make it work, then we've got a potential solution.

    > secure tunnel between them.

Between the endpoints...  Ideally between the phones themselves, in fact.

                                -Bill