Re: AW: [enum-wg] COCOM & ENUM ...
- Date: Tue, 14 Dec 2004 16:59:20 -0500
At 03:48 PM 12/14/2004, Jim Reid wrote:
>>>>> "Richard" == Richard Shockey richard@localhost writes:
Richard> HUH are you kidding ... its is because of the basic and
Richard> orthogonal conflict between what carriers need and want
Richard> and what end users need and want.
I'm not convinced that really is (or will be) the case. Alice is an
end user with SIP applications that lookup E.164 numbers in public
e164.arpa tree to find SIP gateways. Fast-forward a few years. Bob's a
telco doing VoIP and SIP and using DNS lookups of E.164 numbers to
route calls in his net and to other operators. What's the difference?
a great deal .. network operators do not generally or historically expose
internal network architectures or border ingress elements into something as
public as the DNS.
the general requirement I have been constantly told is that the result of
the carrier TN2URI translation must not be publicly exposed or amenable to
MiM attack and is generally hidden behind some AA which is why all the
discussion on non terminal NAPTR records.
The applications are both using the DNS to figure out how to find the
right SIP server for some VoIP session (or whatever). Carol sells SIP
server and client software. Will she want to develop, sell and support
different versions of the same thing to Alice and Bob?
Of course not that is why the carrier record would be non terminal and
require out AA in fact most of the architectures I see nearly have only 1
URI for the entire network. A huge wall of SBC's surrounding the VoIP network.
Meantime, what
if Bob wants to dump calls from his network to Alice on Alice's
internet SIP server so that he doesn't have to pay termination charges
to Alice's telco?
Richard> Either bifurcate the tree at Tier one into two non
Richard> terminal NAPTR records (public & carrier)..which BTW will
Richard> break SIP applications since there is no standards any
Richard> where on how to deal with this.
Maybe there should be a standard on this? :-) Though the bifurcation
could also be realised with split DNS.
I do not agree on either point. SIP CUA's would all have to be redesigned
to accept the new DNS structure ..I dont think that is acceptable.
Richard> Two merge T1 and T2 into the national registry which
Richard> makes the registry operator the central repository for
Richard> ALL SIP routing data for both the carriers and end
Richard> users...which at least preserves the existing model of
Richard> the DNS responds with an "answer" ..the carriers can
Richard> still use non terminal records but normal SIP CUA's would
Richard> simply ignore them.
This is too awful for words. I think there's general consensus that
end users should not see core telco routing data.
not if the URI is non terminal it only increases the requirements on the
registry. The Tier 1 Tier 2 constructs were artificial in the first place
to more balance the loads on the DNS and give end user more flexible
options on controlling their NAPTR records.
Richard> Three have two entirely separate trees ..e164.arpa for
Richard> number holders e164.int for carriers. The .int tree
Richard> could be designed to look into apra for answers it is not
Richard> authoritative for. Problem solved.
This gets very ugly very quickly IMO. Operationally such setups would
be very brittle and near-impossible to debug.
what are you talking about ..it would work perfectly well. End user CUA's
do not need to see carrier data so they would never look into carrier.foo
but John is entirely right here the chances of carrier.foo getting off the
ground are problematic though .MOBI did get through ICANN for some reason.
Richard> oh no we're not going down that rat hole of split DNS
It's no more of a rat hole than having yet another domain name with
funky forwarding/fallback on failure modes between the 2 (or more?)
domain names that you seem to favour. I suspect these could be much,
much worse to administer and operate than a split DNS solution. It
would be good to get hard data on the pros and cons of both
approaches. And any others for that matter. Even better would be to
get that data before a lasting decision is made. :-)
Richard> you forget the basic consumer or PBX edge ENUM resolver
Richard> has no need to see the carrier data.
I've not forgotten that at all. I think you have misunderstood
me. Well, I have an accent.... :-)
Suppose some company is writing ENUM-aware telephony software that
needs to figure out which SIP server to use when terminating a call
for some E.164 number. [Note the deliberate hand-waving about where
that software lives or which net the device is on.] How many DNS
lookups and domain names is it going to need to do that?
only one ..if the software is edge based in the case of IP-PBX's or end
user devices, two if the proxy is licensed carrier based ( aka they issue
phone numbers )
the definition of a carrier here is do you or do you not issue phone
numbers..if you do not you will not have access to the carrier data and BTW
that will not guarantee that the network provider will even give you access
to the network .. the two carriers will have presumed to have a bi-lateral
agreement in place covering inter network transactions.
From a
developer's perspective, how will the software know which net it's in
so it knows which domain names to try (and in what order)?
>> A centralised database could well mean telcos expose their
>> customer and call routing data to each other. Which is unlikely
>> to get much acceptance.
Richard> Well then you have argued that LNP databases dont work
Richard> and I have it on good authority that they do :-)
You would say that, wouldn't you? :-)
Does a number portability database disclose to TelcoA how TelcoB
routes calls around its networK?
no only the destination endpoint or LRN in the case of the US and Canada.
The carrier TN2URI scheme would not expose internal network archichecture
either under the current designs I've seen ..only the location of the
network Session Border Element or Controller. The terminating carrier
network would still need to look up into its own routing tables ..and this
is where I see SIP redirect all over the place..to find the actual end
point routing data.
There is no doubt in my mind BTW that SIP redirect servers are being used
to replicate the functionality of Service Control Points (SCP's) in the IN
and that SIP is becoming the new NGN equivalent of TCAP.
But even exposing the LRN does permit the originating carrier to deduce a
great deal about the called party network provider...in the first case you
know the number has been ported and from the LRN tables you can find out
who that carrier is. In the US and Canada LIDB will give you everything
else you want to know about the customer.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Richard Shockey, Senior Manager, Strategic Technology Initiatives
NeuStar Inc.
46000 Center Oak Plaza - Sterling, VA 20166
sip:rshockey(at)iptel.org sip:57141@localhost
ENUM +87810-13313-31331
PSTN Office +1 571.434.5651 PSTN Mobile: +1 703.593.2683, Fax: +1 815.333.1237
<mailto:richard(at)shockey.us> or <mailto:richard.shockey(at)neustar.biz>
<http://www.neustar.biz> ; <http://www.enum.org>
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