RE: [Ecrit] RE: Comments on: draft-ietf-ecrit-phonebcp-01

["Winterbottom, James" <James.Winterbottom at andrew.com>]

I think that there is one other variant on two.

The End-point makes the call the service URN and includes a provided
locationURI. Outbound-proxy does nothing special.

> -----Original Message-----
> From: Brian Rosen [mailto:br at brianrosen.net]
> Sent: Friday, 1 June 2007 10:36 PM
> To: 'Matt Lepinski'; 'ECRIT'; 'James M. Polk'
> Subject: [Ecrit] RE: Comments on: draft-ietf-ecrit-phonebcp-01
> 
> Thanks for your comments.
> 
> The BCP really shouldn't be SIP specific.  We need to broaden it to,
for
> example, XMPP.  We can have SIP specific information, but it should be
> discussed as just that.
> 
> There is a consensus, I believe, on how to mark emergency calls,
> represented
> by the thread, but chairs have to call consensus, not me.  I think
there
> are
> three cases:
> 1. The endpoint recognizes it's an emergency call, does the LoST
routing,
> and passes the call to its outbound proxy server.  In this case the
> Request
> URI will be the PSAP URI from LoST, and adds a Route header with the
> service
> URN.
> 2. The endpoint recognizes it's an emergency call, but doesn't LoST
route
> it.  In this case the Request URI would be the service URN.  The
outbound
> proxy server would do the LoST routing, put the Route header with the
> service URN in and change the Request URI to the PSAP URI.
> 3. The endpoint doesn't even recognize it's an emergency call.  In
this
> case, the endpoint would put the dialstring in the Request URI.  The
> outbound proxy would behave as in 2 above.
> 
> When the PSAP gets the call, it will always have its URI in the
Request
> URI,
> and there will be a service URN in a Route header.
> 
> Probably, phonebcp should say that more clearly.
> 
> Brian
> 
> > -----Original Message-----
> > From: Matt Lepinski [mailto:mlepinski at bbn.com]
> > Sent: Friday, June 01, 2007 12:49 AM
> > To: ECRIT; James M. Polk; br at brianrosen.net
> > Subject: Comments on: draft-ietf-ecrit-phonebcp-01
> >
> > Brian and James:
> >
> > First, two very high level questions.
> >
> > A) [Is this document supposed to be SIP-Centric?] It is unclear to
me
> > whether the document is intended as a BCP for SIP User Agents and
SIP
> > proxies, or whether it is more generally a BCP for end points and
> > signaling-path devices which may or may not use SIP. For instance,
> > Section 6.4 is written as though SIP signaling were a special case,
and
> > yet paragraph four of Section 5 indicates that all emergency calls
on
> > the wire should contain a Route header (which is a SIP-specific
> > signaling component). Personally, I don't care whether or not the
> > document is SIP centric, or whether SIP is a special case, as long
as
> > the document is consistent.
> >
> > B) [Is there consensus on how to mark emergency calls?] The current
> > version of phonebcp indicates that (in the normal case when
end-points
> > perform the LoST mapping) emergency calls are marked by putting the
URN
> > in a Route header (with a "loose" parameter that I'm not familiar
with
> > ... can someone provide me with a reference) and that the URN is
placed
> > in the Request-URI when the end-point is unable to perform the LoST
> > mapping). Personally, I don't understand the current mechanism
because
> > I'm not sure what an "ordinary" (RFC3261-compliant) proxy does when
it
> > sees a service URN in the top Route header. However, given the long
> > discussion that occured on call marking in January (See:
> > http://www1.ietf.org/mail-archive/web/ecrit/current/msg02963.html),
> > perhaps the more important question is "Has consensus been reached
that
> > (something like) the current mechanism is an appropriate way to mark
> > messages?"
> >
> > ---------------------------------
> > More detailed comments:
> >
> > Section 2: (paragraph 3 - number 2)
> > Is it clear what the "visited location's emergency number" means in
this
> > context?
> > Consider changing to "the local emergency number for its current
> > location" or providing a forward reference to the discussion of
> > dial-strings in Section 5.
> >
> > Section 2: (paragraph 4)
> > I agree with Barbara that if this is intended to an overview of call
> > setup for the special case of an Ethernet connected phone then the
> > bullets should match up more clearly with the numbered items in the
> > previous paragraph.
> >
> > Section 2: (last paragraph)
> > It is unclear whether the antecedent of "it" in the last paragraph
is
> > [RFC4103] or [RFC4504].
> >
> > Section 3:
> > Consider changing "should support" to "SHOULD support"
> >
> > Section 3: (paragraph 2)
> > It seems that the point of this paragraph is to say that a certain
class
> > of devices that communicates over IP networks should support
emergency
> > calls. However, I find the phrase "using current (evolving)
standards"
> > to be unclear and in particular I'm not sure what the phrase
modifies.
> > (E.g. Do you mean "Devices that create media sessions using current
> > (evolving) standards and exchange audio ...")
> >
> > Section 4: (first paragraph)
> > Consider replacing "the norm" with "required" (or a similar word). I
> > think the point is not that automatic location is common/normal but
that
> > it is necessary since most users are unable to provide accurate
> location.
> >
> > Section 4.1: (first paragraph)
> > I think "cellular" (or "traditional wireless")  is more precise than
> > "mobile".
> >
> > Section 4.2: (first paragraph ... also, the last paragraph)
> > Consider changing the phrase "the desired result" to something like
"an
> > equivalent result", or perhaps something even more explicit.
> >
> > Section 4.2: (first paragraph)
> > Consider addition a phrase to the last sentence indicating why it is
> > recommended that the network support a standardized LCP. (This may
not
> > be obvious to the reader). Also, consider changing "recommended" to
> > "RECOMMENDED".
> >
> > Section 4.2: (paragraph 2)
> > Given that the paragraph covers what both devices and access
networks
> > MUST support, consider changing "For all other devices" to "In all
other
> > scenarios".
> >
> > Section 4.3: (paragraph 3)
> > The term "geo-location" is not used in RFC 3825 to describe a
> > lat/lon/alt - style location. (Instead it uses terms like a
> > "coordinate-based geolocation"). Also, given that the "geolocation"
> > header allows for civic locations, I think using geo-location here
is
> > potentially confusing.
> > Note: This comment also applies to the use of "geo reported" in the
> > third paragraph of Section 6.3
> >
> > Section 4.4:  (last paragraph)
> > Consider re-writing the second-to-the-last sentence as: "Certain
> > commonly-used techniques for measuring location create a conflict
> > between the time it takes to generate a precise location and the
desire
> > to route the call quickly." (Also, in the following sentence I think
> > "precise" is a better word than "accurate")
> >
> > Section 5: (paragraphs 5 and 6)
> > Paragraph 5 says that devices MUST mark calls using a service:sos
URN.
> > However, paragraph 6 says that mapping from dialstring to URN SHOULD
be
> > done by the endpoint. Either both paragraphs should use "MUST" or
else
> > they should both use "SHOULD".
> >
> > Section 5: (paragraph 8)
> > I don't understand what it means to be "roaming" or "nomadic" in a
> > system where there is no "visited network"
> >
> > Section 5: (last paragraph)
> > The last sentence of this paragraph seems to be redundent. Consider
> > deleting it.
> >
> > Section 6.1:
> > I agree with Barbara that the use of IPSec should not be prohibited
by
> > this BCP.
> >
> > Section 6.1: (number 6)
> > These instructions are for the User Agent,  P-Asserted-Identity
headers
> > and Identity headers should not be inserted by the UA
> >
> > Section 6.1: (number 10)
> > This item is unclear to me. Is the author's intention that this item
> > handles the case where a UA does not know its own location? If so, I
> > guess that updating this item should be deferred until consensus is
> > reached on location-hiding.
> >
> > Section 6.1:
> > Consider Re-ordering the items as:
> > 11, 10, 12, 14, 15, 13
> > Also, consider deleting 12, I believe it is redundent given 9, 10
and
> 11.
> >
> > Section 6.2: (number 1)
> > Consider adding an example after "... URN appropriate for the
emergency
> > dialstring." That is, consider adding (e.g., ...)
> >
> > Section 6.2: (number 3)
> > I'm afraid that I don't understand the meaning of this sentence.
> >
> > Section 6.3: (paragraph 3)
> > The sentence that begins "This can be an enclosing ..." is unclear
to
> > me. Are you suggesting that when a PSAP coverage region is complex,
that
> > a LoST server SHOULD return a simple polygon that (a) contains the
> > location of the device; and (b) is entirely contained within the
PSAP
> > coverage region?
> >
> > Section 6.5: (number 3)
> > This seems to imply that proxies should expect to SUBSCRIBE to
Presence.
> > Do you mean that proxies should expect the PSAP to SUBSCRIBE to
> Presence?
> >
> > Section 6.5: (number 4)
> > I'm not very familiar with Session Timers, can you provide a
reference.
> >
> > Section 6.6:
> > I'm afraid I don't understand the parenthetical remark after the
"Call
> > Forward" bullet. (Consider removing the remark or re-wording it if
it is
> > important).
> >
> > Section 7:
> > Given the text in Section 4.4 it seems to me that the first
paragraph of
> > Section 7 is redundent and should be deleted.
> >
> > Section 10.2:
> > Given the difficulty of implementing location signing in a useful
> > manner, I think that that either paragraph 2 should either be
removed or
> > else it should reference some other document that explains location
> > signing in more detail. (That is, one paragraph does not do location
> > signing justice and it seems irresponsible to strongly recommend
> > location signing without providing additionaly guidence to the
> > implementor).
> >
> > -------------------------------------------------------------------
> > Minor Nits: (That don't change the meaning of the text)
> >
> > Section 2: (last paragraph)
> > Put a space between [RFC4103] and "media"
> >
> > Section 3: (paragraph 1)
> > Add commas to second sentence "Future PSAPs will, however, support
..."
> > and remove the extra period at the end of the sentence
> >
> > Section 4.1: (paragraph 2)
> > Change "... where it is the access network that knows the location
..."
> > to "... when only the access network knows the location ..."
> >
> > Section 4.4: (paragraph 1)
> > Change "... process engaged from establishing a VPN ... " to "...
> > process engaged by establishing a VPN ..."
> >
> > Section 4.4: (paragraph 2)
> > Change "... related to the mobility of the device and ..." to "...
> > related to the degree of device mobility and ..."
> >
> > Section 4.4: (paragraph 2)
> > Combine the final 2 sentances as follows:
> > "When a device is aware that it has moved, for instance when it
changes
> > access points, the device SHOULD refresh its location."
> >
> > Section 4.4: (last paragraph)
> > Change "... getting more recent location ..." to "... getting
updated
> > location ..." or "... obtaining a fresh location"
> >
> > Section 5: (first paragraph)
> > Consider re-writing as:
> > "A device (or a downstream signaling element) identifies an
emergency
> > call by an "address", which in most cases is a dialstring, although
> > other user interfaces may be used."
> >
> > Section 5: (paragraph 2)
> > First sentence has too many words modifying the word "element".
> Consider:
> > "Note: It is undesirable for a user-interface to enable a user to
place
> > an emergency call by pressing a single button."
> >
> > Section 5: (paragraph 3)
> > Consider changing the first sentence:
> > "... in other countries there are several 3 digit numbers used for
> > different types of emergency calls."
> >
> > Section 5: (paragraph 6)
> > Change "... some entity needs to ..." to "... some entity on the
> > signaling path must ..."
> >
> > Section 5: (paragraph 9)
> > Change "... from North America, the home ..." to "... from North
> > America, then while in North America the home ..."
> >
> > Section 5: (last paragraph)
> > Add a close parenthesis ")" after "dialstrings."
> >
> > Section 6:
> > Change "... is expected be supported ..." to "... is expected to be
> > supported ..."
> >
> > Section 6.1:
> > Change "signaling Method" to "signaling method" (lower case).
> >
> > Section 6.1: (number 1)
> > Change "To: SHOULD" to "Request-URI: SHOULD"
> >
> > Section 6.1: (number 2)
> > Add a space between [I-D.rosen-iptel-dialstring] and "with"
> > Also change "sips MUST be ..." to "a sips URI MUST be ..."
> >
> > Section 6.2: (number 1)
> > Change "If it finds it it MUST:" to "If it finds the dialstring it
> MUST:"
> > Also, change "... for the endpoint" to "... of the end device."
(note
> > that period was missing)
> >
> > Section 6.3: (paragraph 3)
> > Non-parallel sentence structure. Consider re-writing the last
sentence
> as:
> > "In the case of civic location, the LoST server SHOULD report that
the
> > same mapping is good within a community name or even a street, as
this
> > is helpful for WiFi connected devices that roam and obtain civic
> > location from the AP to which they connect."
> > (Or perhaps "Despite the fact that civic location is uncommon for
mobile
> > devices, the LoST server SHOULD ...")
> >
> > Section 6.3: (paragraph 4)
> > Change "... URI of the service URN ..." to "... URI of a service URN
> ..."
> >
> > Section 6.3: (last paragraph)
> > Re-write the last sentence as: "The proxy then replaces the
Request-URI
> > with the resulting PSAP URI."
> > Or perhaps "The resulting PSAP URI then replaces the Request-URI"
> >
> > Section 6.4: (first paragraph)
> > Consider adding the phrase "Once the mapping to a PSAP URI has been
> > performed," to the begining of the paragraph (to improve the flow of
the
> > document).
> >
> > Section 6.6:
> > Change "The emergency dialstrings ..." to "Emergency dialstrings
..."
> >
> > Section 7: (paragraph 3)
> > Change "For calls send with ..." to "For calls sent with ..."
> >
> > Section 8: (paragraph 1)
> > Change "... media streams on RTP ... " to "... media stream using
RTP
> ..."
> > or perhaps "... media streams via RTP ..."
> > Also, consider re-writing the 4th sentence as:
> > "Future IP-enabled PSAPs should accept a wider array of potential
media
> > types."
> >
> > Section 8: (paragraph 2)
> > Add a period between "the offer" and "Silence suppression".
> >
> > Section 10:
> > Change "... it specifies use of several ..." to "... it specifies
the
> > use of several ..."
> >
> > Section 10.1: (paragraph 2)
> > Change "... DHCP is the LCP [RFC3118] ..." to "... DHCP is the LCP,
> > [RFC3118] ..." (add a comma)
> > Also, change "... spoofing would be ..." to "... spoofing is ..."
> >
> > Section 10.1: (last paragraph)
> > Add an 's' to change "Client SHOULD" to "Clients SHOULD"
> >
> > Section 10.2: (last paragraph)
> > Change "... signaling would help significantly." to "... signaling
helps
> > significantly."
> 
> 
> 
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