RE: Diffserv Code Point for Emergency calls

If calls to a locally pre-specified emergency number (e.g., 911) are
given high priority, it is no great exposure.
One would think such calls would have locally routable destinations
and couldn't travel very far or be used for DDOS attacks.  (Except
against the actual emergency systems. How we protect them is another
problem. )

In the absence of limited addressing or strong user authentication (as
the DOD uses) giving Joe Hacker the ability to get extra high priority
seems like a bad idea to me.

It would be helpful if someone (probably ITU rather than IETF) could
standardize on a limited number of local emergency calling numbers.

Steve Silverman


> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf
> Of Reinaldo Penno
> Sent: Saturday, October 22, 2005 8:46 AM
> To: James M. Polk
> Cc: [email protected]; ken carlberg
> Subject: RE: [Ieprep] Diffserv Code Point for Emergency calls
>
>
> Your point is well taken James.
>
> I guess the risk is no different from what we face nowadays
> with doom
> packets marked with EF DSCP. The solution as well is no
> different from
> what we have today to deal with those packets. Usually
> independently of
> the DSCP an endpoint might put in a packet, the edge router perform
> classification and if necessary remarks the packet with
> whatever DSCP it
> should have.
>
> Therefore, if we just continue with just EF for normal and emergency
> voice calls, the risk is the same, the drawback that I see
> is that we
> cannot prioritize emergency over normal calls.
>
> So, in general an edge device that can perform SIP parsing and mark
> emergency calls with the emergency DSCP and others with EF DSCP.
> Alternatively, in a decomposed gateway scenario the SIP
> Proxy can let
> the router know that a certain call is an emergency and
> that it should
> be marked differently.
>
> Regards,
>
> Reinaldo
>
>
> > -----Original Message-----
> > From: James M. Polk [mailto:[email protected]]
> > Sent: Friday, October 21, 2005 11:02 PM
> > To: Reinaldo Penno
> > Cc: ken carlberg; [email protected]
> > Subject: Re: [Ieprep] Diffserv Code Point for Emergency calls
> >
> > Reinaldo
> >
> > Adding fuel to a discussion that has churned on many
> lists over the
> last
> > several years, I'd really want to understand the threat anaylsis
> observed
> > by such a proposal (for a emergency DSCP) to ensure it
> could not be
> used
> > for a fairly trivial to generate DDOS on the network -
> even all the
> way to
> > the PSAP, or just used by neighbors wanting the very best
> throughput
> for
> > their game of Doom.
> >
> > At 10:57 AM 10/21/2005 -0400, ken carlberg wrote:
> > >Hello Reinaldo,
> > >
> > >>I read
> >
> >>http://www.ietf.org/internet-drafts/draft-ietf-ieprep-fram
> ework-10.txt
> > >>and was somewhat puzzled at section 4.1.2. I understand that the
> IETF
> > >>wants to be conservative in standardizing new DSCP, but
> it seems to
> an
> > >>emergency call DSCP would be accepted by the community (am I
> wrong?).
> > >
> > >well, from my own take, I would say that the "community" is not
> > >against an emergency call DSCP per se, but rather awaits specific
> > >proposals with a cautious mindset.  Recall from that
> section 4.1.2
> > >that there is a need to define a behavior in addition to
> identifying
> > >a code point.  So if you want a code point of 1 or more bits for
> > >"emergency", what would be its defined forwarding behavior?
> > >
> > >one such proposal, primarily aimed at MLPP, is called Multi-Level
> > >Expedited Forwarding (MLEF) and can be found at:
> >
> >ftp://ftp.rfc-editor.org/in-notes/internet-drafts/draft-silverman-
> > >tsvwg-mlefphb-03.txt
> > >
> > >I would also suggest reading a counter proposal that
> avoids defining
> > >a new DSCP:
> >
> >ftp://ftp.rfc-editor.org/in-notes/internet-drafts/draft-ietf-tsvwg-
> > >mlpp-that-works-02.txt
> > >you can dig around the TSVWG archives over the past 2
> months for some
> > >comments on the draft.
> > >
> > >-ken
> > >
> > >
> > >_______________________________________________
> > >Ieprep mailing list
> > >[email protected]
> > >https://www1.ietf.org/mailman/listinfo/ieprep
> >
> >
> > cheers,
> > James
> >
> >                                  *******************
> >                  Truth is not to be argued... it is to be
> presented.
>
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