RE: 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-framework-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
> >
> >
> >_______________________________________________
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> >[email protected]
> >https://www1.ietf.org/mailman/listinfo/ieprep
> 
> 
> cheers,
> James
> 
>                                  *******************
>                  Truth is not to be argued... it is to be presented.