Subject: Re: [Ieprep] Comments on draft-carlberg-ieprep-framework

From: [email-masked]
Date: Wed, 13 Mar 2002 18:55:03 EST

In a message dated 3/12/02 3:50:06 PM Eastern Standard Time, [email-masked] 
writes:

> At 08:08 AM 3/12/2002, [email-masked] wrote:
> >The idea is that there could be many different agencies/persons/functions 
> >that need emergency access - FEMA, police, medical, Red Cross, network 
> >administrators, etc. It's hard to image that all would be treated the 
> >same. If there is only one possible level to apply to all, it would be 
> >very difficult to decide whether or not a particular group would get the 
> >authorization, e.g., is the Red Cross one that needs this? Providing a way 
> >to distinguish would help. Whoever administers the authorization to use 
> >emergency levels in a network would decide who gets which level. Within 
> >"emergency" there needs to be 3 or 4 levels. (Remember, In MLPP, or 
> >"Assured Service", one could think of the 5 levels of precedence as 
> >consisting of a "Routine" level, and then four levels of "emergency".)
> 
> Perhaps, but you're mixing apples and orangutans. Providing a way to 
> distinguish calls is probably a good thing. Using the standard that defines 
> the label with which you identify traffic to define the policy to apply to 
> those various distinguished kinds of calls dramatically reduces your 
> flexibility, and brings you into a global space you are not thinking about. 
> 

(See my comment below about this issue of naming labels.)

> eing able to say "This is a FEMA Code 27 call" (distinguishing calls) is 
> quite a bit different than saying "This is a FEMA Code 27 call, all 
> telephone systems in the world including those deployed in Madagascar need 
> to be able to understand what that means, and by the way that means that my 
> call should be placed ahead of a call for the Red Cross but behind a call 
> 

What I meant is that there might be 3 levels for emergency calls and FEMA is 
authorized to use the highest one and maybe the Red Cross is only authorized 
to use the lowest. When FEMA makes a call, they can designate the call as the 
highest level (which must be authenticated). The network policy knows how to 
handle it and how (and if) to give it better service than a call from the Red 
Cross which designates the lowest level. This is identical to MLPP today and 
what we need for what I called "Assured Service". Whether there are 
interworking policies with a network in Madagascar is another issue.

> 
> By all means, put identifying marks on calls. Leave the policy to be 
> applied to those calls ("all telephone systems in the world including those 
> deployed in Madagascar need to be able to understand what that means, and 
> by the way that means that my call should be placed ahead of a call for the 
> Red Cross but behind a call which might launch missiles") to the network.
> 
> It's not obvious to me, by the way, that '5 levels of precedence as 
> consisting of a "Routine" level, and then four levels of "emergency"' is 
> 

It's what the US military and many others have been using for years and it is 
the basic requirement we have for them to use Voice over IP.

   Take a recent case in point: on September 11, the calls directing 
emergency traffic to the lower Manhattan or around the
> Pentagon were not "authorized" folks, they were Joe Citizen who was in no 
> way special but happened to be on the scene. Cutting Joe Citizen out of the 
> loop, while enabling "authorized" access to folks whose first instinct 
> would have been to call home and say they were all right, would have been 
> at least as disruptive to emergency services deployment as the fact that 
> Joe Citizen also wanted to call home. Precedence makes sense when you have 
> the power to choose; as I understand the GETS network, it doesn't choose 
> whether or not to place a call as it does choose whether to let a person 
> 

I'm surprised. The above statement sounds like you do not support the idea of 
providing "authorized" precedence for anyone, not even emergency workers, 
just because Joe Citizen might sometimes be in a better position or because 
some "authorized" person might misuse it.

> 
> >>What makes sense to me in SIP is a simple statement: "I assert that this 
> >>call is an emergency call". If you are not authorized to make that 
> >>assertion, the correct policy is to ignore the statement. If you are 
> >>authorized, the network will have a policy to apply such as "permit this 
> >>call even if we are well into the overload zone" or "drop a random call 
> >>in order to complete this one." The network should determine the policy, 
> >>not the standard.
> >
> >Not sure of your point. The standard should allow a way to designate 
> >sufficient levels of importance, in order for a network to apply whatever 
> >its policy is.
> 
> And who decides what is important and what is not? I think you'll find that 
> someone standing on the corner watching people bleed will feel their calls 
> are *very* important, while someone with a different perspective might 
> decide that places where lots of people are bleeding are more important 
> than places where only a few are. My point is that that the policy must 
> describe how to make that decision - the network policy must decide whether 
> one thing is more important than another. As such, it cannot be placed in 
> the hands of the actor who has only a small part of the picture. It must be 
> done by the network.
> 
> Therefore, you want the person making the call to identify the issue in 
> some way, and let the network apply a pre-determined policy to decide what 
> resources to apply to it.
> 

Again, your statement sounds like to do not agree with the basic premise of 
the work - that someone (i.e., the government) decides on who has 
authorization to use the emergency level for calls. Note that the case of 
someone standing on the corner reporting someone bleeding is normal 911 call, 
which is separate from authorized emergency calls (maybe from someone in a 
position to report lots of people bleeding). I don't understand the point 
that "you want the person making the call to identify the issue". SIP 
signaling obviously can't include a description of the emergency situation so 
the network can work out relative priorities with other descriptions. The 
originator has to specify a level (maybe one of many) and the network has to 
compare levels.
 .
> >The question is: how many distinct levels are needed?
> 
> You have yet to demonstrate that the concept of "levels" is decidable on a 
> global basis. Is a FEMA call more important than its counterpart in 
> Madagascar? Is that a nonsense question? If it is a nonsense question, why 
> are we discussing it in the context of a standard for products that will be 
> 

Yes, it's a nonsense question if there is some concept of different networks 
in the two places. Each would have a definition of what the emergency levels 
are and how to handle them. A FEMA call doesn't contend with one in 
Madagascar, unless there is some SLA between the networks and they have 
agreed on the mapping of meanings. If your view is one giant, ubiquitous 
network worldwide, then I have no idea how to handle this issue based on the 
current approach. No, I dont' think the issue of "levels" is decidable on a 
global basis, and, no, we shouldn't be writing a standard that is specific to 
the US. That was the point of my comments months ago on SIP saying that we 
should define the precedence levels in the standard as 0,1,2,3,4 and let each 
networks use them as they see fit. There is no reason to believe that 
Madagascar would label their levels the same as the US.

> 
> >>>4.1.2 Diff-Serv
> >>>
> >>>[snip] In this example, there would need to be the 5 drop precedence 
> >>>levels for EF, as well as for each AF class, since eventually there 
> >>>should be a need to apply precedence type services to other traffic 
> >>>types besides voice. Clearly, there are not enough available DSCP code 
> points.
> >>
> >>I think you have a very different understanding of diffserv than I do. 
> >>When you talk about a drop precedence for EF (which doesn't have a drop 
> >>precedence), what are you talking about - dropping packets, or dropping 
> calls?
> >
> >The current draft shows "EF for voice, with signalling of bandwidth".
> 
> There are 51 posted drafts that contain the words "voice", "signalling", 
> and "bandwidth". I have just reviewed all of them and have not found those 
> 

I was referring to draft-baker-ieprep-requirements-00 in section 2.4. Sorry 
about the double "l" in signaling in my comments.

<> snip>

> If what you want to define is an EF service with multiple drop precedences, 
> I would strongly suggest that you define an EF service with multiple drop 
> precedences. When you do, remember that in computer science there are three 
> reasonable numbers: "zero", "one", and "many". I can tell you for sure what 
> will happen if you prioritize some traffic over other traffic - loss, 
> delay, and variation in delay (jitter) will be transferred from the 
> prioritized traffic to the other traffic. I think I can tell you what will 
> happen with two priorities if the priorities map respectively to voice and 
> video traffic. Folks have done a zillion simulations on priority systems 
> with more levels, and have not been able to demonstrate utility on a 
> per-packet level.
> 
By your last statement do you mean that no one has demonstrated utility for 
any per-packet priority system or one with more than 3 levels? I had no 
intention of suggesting that we apply "priority" on a per-packet basis within 
a class, only selection of what is dropped (as AF does). You noted in your 
comments that the requirement for voice is "minimal jitter, latency, and loss 
for a data stream" and "EF accomplishes that by measuring rate, dropping 
excess, and giving priority to the rest." As far as I know, there is no way 
to control which packets get dropped. We would like to add five drop 
precedences to correspond with the 5 precedence levels of calls.

See you in Minneapolis.

Mike Pierce

---

From: Fred Baker <[email-masked]>
Date: Wed, 13 Mar 2002 17:28:06 -0800

At 03:55 PM 3/13/2002, [email-masked] wrote:
>What I meant is that there might be 3 levels for emergency calls and FEMA 
>is authorized to use the highest one and maybe the Red Cross is only 
>authorized to use the lowest.

That still couples the policy (levels of emergency-ness, which translate 
into ways of servicing those calls) with the labeling scheme (four numbers, 
which you would like to raise to five),

>[one routine level plus four levels of emergency are] what the US military 
>and many others have been using for years and it is the basic requirement 
>we have for them to use Voice over IP.

That makes it right? Are you sure there is not a need for five levels of 
emergency somewhere, or that the four levels that are in use are properly used?

>The above statement sounds like you do not support the idea of providing 
>"authorized" precedence for anyone, not even emergency workers, just 
>because Joe Citizen might sometimes be in a better position or because 

I am on record as not being crazy about it as stated, for reasons which I 
have articulated in the past. I do believe that policy should be applied in 
placing calls, and that this might include preferential distribution of 
service. But who says that "emergency-ness" is the only contributing 
factor, or should get a she-gets-it-he-doesn't veto capability? I rather 
strongly think that if you pull the policy out of the definition of the 
label, you can apply whatever policy you want (such as varying levels of 
emergency-ness) within your domain, and let someone else apply whatever 
policy they want in theirs.

What I have a problem with is trying to force everyone to use the same 
policy model. I can't think of any two networks in the world that have 
exactly the same policy model.

In short, if it is done, I want it to be done in a manner which not only 
works for the US Military within the DISA network, but works in other 
networks as well, and can apply whatever policy is applicable in whatever 
place. I also want it to apply on a call basis, not a packet basis, unless 
it can be shown that the packet capabilities in fact materially help.

>>You have yet to demonstrate that the concept of "levels" is decidable on 
>>a global basis. Is a FEMA call more important than its counterpart in 
>>Madagascar? Is that a nonsense question? If it is a nonsense question, 
>>why are we discussing it in the context of a standard for products that 
>>will be used without change in both the US and Madagascar?
>
>Yes, it's a nonsense question if there is some concept of different 
>networks in the two places.

>No, I dont' think the issue of "levels" is decidable on a global basis, 
>and, no, we shouldn't be writing a standard that is specific to the US. 
>That was the point of my comments months ago on SIP saying that we should 
>define the precedence levels in the standard as 0,1,2,3,4 and let each 
>networks use them as they see fit.

There is one global Internet, and the one SIP standard is used equally in 
all parts of it. That one Internet is composed of various smaller networks, 
but trust me, it is border-blind and within any large network operates in 
many countries. When you say "the government authorizes the use of various 
levels of <mumble>", in the Internet, I don't know who you're talking about 
doing the authorizing - the UN? Yes, this is a fundamental difference from 
the telephone system. It is a difference which needs to be taken into account.

Let's take two examples. Cisco is a multi-national corporation, with 
service by I don't know how many providers. It has at least four DMZs to 
the outside world, in Sydney Australia, San Jose California, RTP North 
Carolina, and Amsterdam Holland. It also has internal service in a truly 
long list of countries. Cable and Wireless (an ISP) has service in upwards 
of 70 countries run through one global ISP, and several wholly owned 
subsidiary networks. C&W and Cisco are each a single network.

>By your last statement do you mean that no one has demonstrated utility 
>for any per-packet priority system or one with more than 3 levels?

pretty much. I know that systems like that can be defined. However, it is 
in no sense obvious from simulation results they result in a significant 
change to the traffic flowing through them over what would happen with 
lower numbers of priorities.

>You noted in your comments that the requirement for voice is "minimal 
>jitter, latency, and loss for a data stream" and "EF accomplishes that by 
>measuring rate, dropping excess, and giving priority to the rest." As far 
>as I know, there is no way to control which packets get dropped. We would 
>like to add five drop precedences to correspond with the 5 precedence 
>levels of calls.

Can you give me an idea why you haven't discussed that with the authors of 
draft-ietf-diffserv-rfc2598bis-02.txt and 
draft-ietf-diffserv-ef-supplemental-01.txt, soon to be RFCs 3246/3247? If 
you could have demonstrated the case, you could have had it in the 
specification. Since we have gone to the effort to take them to RFC, at 
this point it will be an especially tough sell to re-open the documents.

Five drop precedences added to EF might make sense; as I said before, it's 
not obvious to me that it does, but I'm willing to be shown your 
simulations that prove that the service still works after it is done and 
that this materially affects something.

Understand that network bottlenecks are not generally the issue any more 
except in access paths, at least in the US and Europe. Even on Sept 11, 
according to reports, the issues in the Internet were with servers, not 
backbone traffic or even access network traffic. VoIP with *no* levels of 
priority, no bandwidth reservation, and no central switch facility worked 
quite well in lower Manhattan, providing telephone access through NYSERNET 
and other networks in the area; having lost or damaged several switches in 
the area, the standard telephone system had some serious problems to 
overcome (statement not intended to be a slam on the telephone network, but 
an accurate statement of facts - they had a tough couple of weeks and 
pulled some really long hours, for which they deserve a lot of credit).

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---

From: Fred Baker <[email-masked]>
Date: Wed, 13 Mar 2002 18:09:20 -0800

>this point it will be an especially tough sell to re-open the documents.

having said that, let me go on to say that there is nothing whatsoever to 
stop DISA from configuring its network with four extra local-assignment 
code points that are applied to traffic on some appropriate manner that 
accomplishes five drop precedences within EF service. Diffserv only 
recommends a code point for EF; there is nothing to say you can't use a 
different one, or five. If this only applies in your network, that doesn't 
have to be standardized.

---

From: "James M. Polk" <[email-masked]>
Date: Thu, 14 Mar 2002 13:38:31 -0600

> originator has to specify a level (maybe one of many) and the network has to

A possible mechanism exists within the SIP R-P Header in the case you argued
against earlier in another context, the statement allowing the response (200
OK) to set the level. Perhaps this is a case where I'm personally allowed to
make a call (but the network doesn't know it yet) and I INVITE to a specific
URI (the equvelent of today's GETS number), this could have the receiving end
change my original namespace.value up to whatever it needs to be for that call
in the cases where it's been established that "this call is should be routed to
FEMA, or to the RED CROSS, or to the LOCAL FIRE DEPARTMENT (only). SIP
redirects and Re-INVITES might be needed, but that should be unaware to the
caller making the call unless this is after some form of authentication is
required from that caller (pin # or something else).

*************************************
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James M. Polk
Consulting Engineer
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