Subject: RE: [Ieprep] Diffserv Code Point for Emergency calls

From: "Reinaldo Penno" <[email-masked]>
Date: Thu, 27 Oct 2005 23:29:55 -0400

Hello,

I read draft draft-ietf-tsvwg-mlpp-that-works-02, which I assume it is
your proposal.

Some questions:

1. The example is the end if quite complex. I would like to start with a
bare bores one. Which priority you suggest for everyday 911 calls as
opposed to normal telephone calls? I believe the priorities are below

  The DSN has 5 precedence levels of IEPS in descending order:

        dsn.flash-override

        dsn.flash

        dsn.immediate

        dsn.priority

        dsn.routine

2. It seems to me your proposal and an emergency DSCP are complementary
and not mutually exclusive. If signal with RSVP and if you get
bandwidth, you mark packets with the emergency DSCP.

3. Not trying to simplify things but premise of this proposal is that
all IP phones will support RSVP, right? 

4. Should the phones use RSVP just for emergency calls or for all calls
in general? I guess they should otherwise the other devices would loose
track of how much bandwidth has been consumed?

Thanks,

Reinaldo

> -----Original Message-----
> From: Fred Baker [mailto:[email-masked]]
> Sent: Wednesday, October 26, 2005 11:59 AM
> To: Reinaldo Penno
> Cc: James M. Polk; [email-masked]; ken carlberg
> Subject: Re: [Ieprep] Diffserv Code Point for Emergency calls
> 
>  From my perspective, the question in the data plane is not whether
> the packet is part of an emergency session, but whether it is
> authorized to use the bandwidth. Emergency authorization is a control
> plane problem.
> 
> That is why I have suggested authorization of users to use the EF
> code point during CAC.
> 
> On Oct 22, 2005, at 8:45 AM, Reinaldo Penno wrote:
> 
> > 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-masked]]
> >> Sent: Friday, October 21, 2005 11:02 PM
> >> To: Reinaldo Penno
> >> Cc: ken carlberg; [email-masked]
> >> 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
> >>>
> >>>
> >>> _______________________________________________
> >>> Ieprep mailing list
> >>> [email-masked]
> >>> https://www1.ietf.org/mailman/listinfo/ieprep
> >>>
> >>
> >>
> >> cheers,
> >> James
> >>
> >>                                  *******************
> >>                  Truth is not to be argued... it is to be
presented.
> >>
> >
> > _______________________________________________
> > Ieprep mailing list
> > [email-masked]
> > https://www1.ietf.org/mailman/listinfo/ieprep
> >

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---

From: Fred Baker <[email-masked]>
Date: Sun, 30 Oct 2005 08:14:48 -0500

The discussion that is being had right now under the thread "Diffserv  
Code Point for Emergency calls" has been had roughly a zillion times  
since the start of the working group. We have had discussions of  
MLEF, of a single DSCP, and a list of others things. Look in the  
archive; they are there.

CAC as defined in SIP/H.323/<proprietary> applies to the systems that  
participate in the SIP exchange, which would generally be the  
endpoint itself and its controlling proxy - the SIP proxy, the  
gatekeeper, the Cisco Call Manager, or whatever else one uses. It can  
accomplish certain things: if Alice calls Bob when Bob is on the  
phone with Carol, it can tell Bob that his wife is calling and give  
him the opportunity to take the call, and it can permit a pre- 
engineered network to do some fairly general things in terms of call  
counting. Step away from those fixed networks, or run that as an  
enterprise service running over an arbitrary collection of  
intermediate ISPs that don't participate in the service, and life  
becomes far more interesting. For example, Monday evening at the IETF  
there will be an ad hoc BOF discussing the GIG, which has two major  
components in the core - a fixed fiber optic network of arbitrarily  
high speed and a satellite network characterized by single-digit- 
megabit up/down links that have potentially large networks behind  
them. And we could discuss FCS etc, where we are talking about manet  
networks that constantly shift. Say "city of linked hot spots" and  
the various other kinds of networks we are building these days...

BTW, what we are discussing right now is only voice on IP. We already  
have significant use of video on IP, and the subject matter also  
covers requirements for email and a variety of other applications.

We need to stop traveling in circles in the ieprep discussion. Life  
is boring when you pass the same place over and over again without  
reaching the destination.

The objective here, so I'm told, is to enable people like DoD, NATO,  
NCS, and the counterparts of NCS in 193+ countries to build a network  
in which a first responder or an official with certain credentials  
can go anywhere, jack in his laptop-or-whatever (or, in the dreams of  
some, commandeer a laptop-or-whatever), and use it under a policy  
that authorizes him to have acceptable service when nobody else is  
getting acceptable service. There are definitions of "acceptable  
service", and those of us that are working with military and civilian  
networks to build this - those of us for whom this is not an armchair  
exercise - are being held to those definitions rigorously. To do  
that, we need to provide tools for the likes of Verizon and BT to be  
able to deploy and manage those networks, and they need to work in  
the specialized environments that DoD and NATO build.

Would those who advocate simply assigning a DSCP and being done with  
the discussion please explain to us how to build a service network  
that delivers a special service to an authorized user, one that a  
network operator can deploy and use, bill for the service, track and  
minimize fraudulent use, deliver a priority email in 7 minutes as  
specified, deliver both voice and video on IP with "acceptable"  
service as "acceptable" is defined, and so on, without authorization/ 
authentication and using only the very limited CAC designed for a  
fixed-and-specifically-tuned network? Could we get an RFC that  
describes that?

---

From: Fred Baker <[email-masked]>
Date: Sun, 30 Oct 2005 07:37:33 -0500

On Oct 27, 2005, at 11:29 PM, Reinaldo Penno wrote:

> opposed to normal telephone calls?

mlpp-that-works is not a 911 solution; 911 is about providing a  
service in which an arbitrary user goes to a special peer. MLPP (and  
GETS) are about a special user going to a peer of its choosing and  
getting priority service - and about the peer getting priority  
service while communicating with the MLPP-special user.

> I believe the priorities are below
>

that is true in the DSN for MLPP service. There are other networks,  
such as GETS which uses the same names but has two levels, the DRSN  
which has six levels, and ADNS which has seven. GSM allows for 15.

> bandwidth, you mark packets with the emergency DSCP.

why?

In the circuit switch network, MLPP/GETS is about getting a circuit.  
There is nothing special about the circuit - it is the same as any  
other circuit. The question is whether you get one or someone else  
does, and MLPP/GETS makes it so that you get one. Ditto ATM - what is  
the marking in the ATM cell for a VC assigned in a priority manner?  
In the PSTN and the ATM networks, this is all in call control. Having  
done it in call control, there is no need to do anything in the data  
plane. Why should IP be different?

And note the security issue with putting it in the data plane. If you  
build a superhighway for script kiddies, they will come. You will  
still have to authenticate and authorize the use of the special DSCP.  
So the DSCP doesn't do away with the need for call signaling seen by  
the network.

You can gratuitously dump mechanisms in to your heart's content. But  
if you don't need them, why? Note RFC 1958 and 3439's comments on  
simplicity and elegance of design. Note RFC 2804's assertion that the  
the random complexity of traditional LI solutions being the best  
reason to not deploy them. I'd really like an answer.

> all IP phones will support RSVP, right?

no. Only the ones you want to provide an emergency service to. But it  
would be simpler and more reliable if they all did.

There are two ways to manage the service at the data layer. You are  
going to have to have an ACL that ensures that only authorized users  
get to use the magic DSCP, or if you simply use EF you will need an  
ACL that ensures that losses, if they come, come from unauthorized  
users.

> track of how much bandwidth has been consumed?

see above.

>>>>                  Truth is not to be argued... it is to be

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