Subject: Re: GLP, number portability and wireless subscribers

From: "Hussein F. Salama" <[email-masked]>
Date: Tue, 09 Mar 1999 12:44:53 -0800

Jonathan Rosenberg wrote:
> 
> Greg Zhang wrote:
> >
> > >This is another good example of why translation before gateway selection
> > >is a good idea. However, I'm not sure there is much we can do from a
> > >protocol perspective to prevent it. There may be valid reasons why a
> > >company would like to advertise an 800 number (only they own it, for
> > >example), and I'd rather not exclude this possibility. It seems like a
> > >sensible approach is to allow non-routing numbers in GLP, but mention
> > >that there are issues with them, and translation before routing is a
> > >good idea. Does this sound sensible?
> >
> > I think to handle this type of cases correctly, we need to introduce a
> > concept of scope for the advertisement. Gateways in CA will advertise
> > the 800 number for company X in CA while gateways in NY will
> > advertise the same 800 for company Y in NY. The advertisement from
> > the CA domain does not get propagated to the NY domain and vice
> > versa. This way the numbers that are locally significant and are being
> > administrated locally stays local. This however does not prevent the
> > same 800 number being used by upper level for a third customer.
> 
> A sensible idea, but seems hard to do. How does one represent scope? How
> does one encode the notion that "this number is valid within the greater
> new york metropolitan area", or "northern california" into a protocol?
> 
> Perhaps one solution is to allow scopes to be represented as opaque
> tokens. These tokens can be registered, perhaps with IANA, along with a
> desription of the what the scope means. This would allow peers to
> program their LS's to recognize certain scope tokens, and do something
> appropriate with them. Prefixes with unrecognized scope tokens probably
> shouldn't be propagated.
> 
> As an alternative, scope could be represented by a separate phone number
> prefix. This second prefix indicates the set of numbers you need to call
> from for this scope to be defined. For example:
> 
> phone numbers: +1-800-55*
> scope: +1-415*
> 
> means that 800-55* is only defined within parts of California.
> 

Jonathan,

I prefer the second alternative. The scope attribute shouldn't be opaque
to intermediate LSs. I think the scope will factor into aggregation and
route selection. For example, an LS shouldn't aggregate two
advertisements with different scopes. And if an LS receives multiple
advertisements for the same 800 number, each with a different scope, it
shouldn't apply route selection to these advertisements, but rather
continue advertising them all. I think that's necessary for GLP to work
in a topology where non-contiguous administrative domains can accept
calls from the same scope?

Sounds like source+destination based routing with the scope representing
the source prefix. Are there any prior experiences with such a scheme?

Hussein

> Any other ideas? Or do people think that this isn't needed?
> 
> -Jonathan R.
> 
> --
> Jonathan D. Rosenberg                       Lucent Technologies
> Member of Technical Staff                   101 Crawfords Corner Rd.
> High Speed Networks Research                Holmdel, NJ 07733
> FAX:   (732) 834-5379                       Rm. 4C-526
> EMAIL: [email-masked]
> URL: http://www.cs.columbia.edu/~jdrosen

-- 
Hussein F. Salama
Cisco Systems
Mail Stop SJC6/3, 170 W. Tasman Drive, San Jose, CA 95134
Voice: +1 (408) 527-7147, Fax: +1 (408) 527-1714

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From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 09 Mar 1999 14:49:48 -0500

-Jonathan R.

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From: "Greg Zhang" <[email-masked]>
Date: Tue, 9 Mar 1999 11:27:15 -0800

>> Because of the above example, I think all types of translation (800
>> numbers or LNP) and mapping should occur prior to call routing. This is
>> particularly important for 800 numbers, because they have a regional
>> scope in many cases. The same 800 number may owned by company X in CA
>> and company Y in NY. In the above example, the call will be incorrectly
>> routed to company X instead of going to the originally intended
>> destination, company Y.
>

For example, while company X's 800 number is administrated by
PacBell and company Y's 800 number is administrated by NYNEX,
AT&T can assign the same 800 number to company Z located in
Houston, Texas.

The design of the protocol should support these scenarios. It is
up to the telephone network operators to sort out the issues of
conflict and confusion caused by the assignment of same numbers
to different entities in different part or level in the network. These
are business decisions. Ultimately, they are driven by the customers'
need and public's ability to handle the possible confusions. The
protocol should provide mechanisms to carry it out.

- Greg

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From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 09 Mar 1999 16:00:18 -0500

> calls from the same scope?

I agree with your requirements, but don't see how they eliminate
approach 1 (the scope attribute). What you are saying is that:

* an LS can only aggregate two routes if their scope attributes match
* a route selection should not occur across routes for the same prefix
but with different scope attributes

I guess "opaque" is really the wrong word. What I mean is that we should
not try and code a representation of a scope beyond a numerical token.
The meaning of the token would be bound to geographic scopes by means of
registration with IANA (or even proprietary scopes between providers).
We would then be able to define aggregation and selection rules, like
those above, based on whether two scopes match or not, and nothing more.
LS routing policies would be based on specific values, and it would be
up to the administrator to know, for example, that value 10 means "New
York".

-Jonathan R.

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From: "David R. Oran" <[email-masked]>
Date: Tue, 9 Mar 1999 16:24:31 -0500

I don't think it's either needed or desirable to have locally-scoped
numbers, at least at the scale we're talking about for GLP. It would be
like asking IP routing to handle scoping for Net 10 addresses rather
than banning them from crossing any administrative boundaries.

I'm of course willing to be convinced otherwise, but this seems a recipe
for wierd failure modes and horrendous complexity.

Dave.

> -----Original Message-----
> From: Jonathan Rosenberg [mailto:[email-masked]]
> Sent: Tuesday, March 09, 1999 2:50 PM
> To: Greg Zhang
> Cc: [email-masked]; John Schnizlein; David R. Oran; Matt Squire;
> Scott Petrack; Alok Mittal; iptel
> Subject: Re: GLP, number portability and wireless subscribers
>
>
> Greg Zhang wrote:
> >

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