Subject: RE: [Sip] I-D ACTION:draft-ietf-sip-hop-limit-diagnostics-02.txt

From: "Drage, Keith (Keith)" <[email-masked]>
Date: Tue, 6 Jun 2006 16:18:12 +0100

(as WG chair)

The author thinks this document is complete.

If this is true we should be putting it into working group last call, and after that pushing it up to the IESG.

Do you (the SIP WG) agree with author, such that this document is ready, or are there issues you would still like addressed with this document. 

Secondly, in parallel with the WGLC, we would like to see some detailed reviewers. If you would like to do this, particularly if you are attempting to use this draft in some application, please send your names to Dean and myself.

regards

Keith

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]
> Sent: 02 June 2006 20:50
> To: [email-masked]
> Cc: [email-masked]
> Subject: [Sip] I-D ACTION:draft-ietf-sip-hop-limit-diagnostics-02.txt 
> 
> 
> A New Internet-Draft is available from the on-line 
> Internet-Drafts directories.
> This draft is a work item of the Session Initiation Protocol 
> Working Group of the IETF.
> 
> 	Title		: Diagnostic Responses for SIP Hop Limit Errors
> 	Author(s)	: S. Lawrence, et al.
> 	Filename	: draft-ietf-sip-hop-limit-diagnostics-02.txt
> 	Pages		: 12
> 	Date		: 2006-6-2
> 	
> The SIP protocol imposes a limit on the number of hops a request may
> make from a sender to the recipient.  When this limit is reached, a
> 483 error response is returned.  The present form of the 483 response
> does not provide enough information for the sender or proxies on the
> path to diagnose failures whose symptom is that the hop limit is
> reached.  This document proposes additional diagnostic information to
> be returned in a 483 response.
> 
> Comments are solicited, and should be directed to the SIP working
> group list at [email-masked]'.
> 
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-ietf-sip-hop-limit-d
iagnostics-02.txt

To remove yourself from the I-D Announcement list, send a message to 
[email-masked] with the word unsubscribe in the body of the message.  
You can also visit https://www1.ietf.org/mailman/listinfo/I-D-announce 
to change your subscription settings.

Internet-Drafts are also available by anonymous FTP. Login with the username
"anonymous" and a password of your e-mail address. After logging in,
type "cd internet-drafts" and then
	"get draft-ietf-sip-hop-limit-diagnostics-02.txt".

A list of Internet-Drafts directories can be found in
http://www.ietf.org/shadow.html 
or ftp://ftp.ietf.org/ietf/1shadow-sites.txt

Internet-Drafts can also be obtained by e-mail.

Send a message to:
	[email-masked].
In the body type:
	"FILE /internet-drafts/draft-ietf-sip-hop-limit-diagnostics-02.txt".
	
NOTE:	The mail server at ietf.org can return the document in
	MIME-encoded form by using the "mpack" utility.  To use this
	feature, insert the command "ENCODING mime" before the "FILE"
	command.  To decode the response(s), you will need "munpack" or
	a MIME-compliant mail reader.  Different MIME-compliant mail readers
	exhibit different behavior, especially when dealing with
	"multipart" MIME messages (i.e. documents which have been split
	up into multiple messages), so check your local documentation on
	how to manipulate these messages.

Below is the data which will enable a MIME compliant mail reader
implementation to automatically retrieve the ASCII version of the
Internet-Draft.

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip

---

From: Cullen Jennings <[email-masked]>
Date: Wed, 7 Jun 2006 07:34:58 -0700

I think it still has at least one serious question open - that being  
does it help or harm?

The example in the draft, each via is about 87 octets and imagine  it  
had 70 hops or so. This would be a real big response - too big for a  
UDP packet most likely. To follow the congestion safety, I don't know  
how to deal with this. If seems that in many systems, the resource  
would simply be dropped because it is too large. It seems like not  
getting any response would be far worse than getting getting a  
response that did not have the debugging information.

On Jun 6, 2006, at 8:18 AM, Drage, Keith (Keith) wrote:

> If this is true we should be putting it into working group last  
> call, and after that pushing it up to the IESG.
>
> Do you (the SIP WG) agree with author, such that this document is  
> ready, or are there issues you would still like addressed with this  
> document.
>
> Secondly, in parallel with the WGLC, we would like to see some  
> detailed reviewers. If you would like to do this, particularly if  
> you are atteFrom [email-masked] Wed Jun 07 12:15:48 2006
From: Cullen Jennings <[email-masked]>
Subject: Re: [Sip] I-D ACTION:draft-ietf-sip-hop-limit-diagnostics-02.txt 
Date: Wed, 7 Jun 2006 07:34:58 -0700
To: "Drage, Keith (Keith)" <[email-masked]>
Cc: [email-masked]

I think it still has at least one serious question open - that being  
does it help or harm?

The example in the draft, each via is about 87 octets and imagine  it  
had 70 hops or so. This would be a real big response - too big for a  
UDP packet most likely. To follow the congestion safety, I don't know  
how to deal with this. If seems that in many systems, the resource  
would simply be dropped because it is too large. It seems like not  
getting any response would be far worse than getting getting a  
response that did not have the debugging information.

On Jun 6, 2006, at 8:18 AM, Drage, Keith (Keith) wrote:

> If this is true we should be putting it into working group last  
> call, and after that pushing it up to the IESG.
>
> Do you (the SIP WG) agree with author, such that this document is  
> ready, or are there issues you would still like addressed with this  
> document.
>
> Secondly, in parallel with the WGLC, we would like to see some  
> detailed reviewers. If you would like to do this, particularly if  
> you are attempting to use this draft in some application, please  
> send your names to Dean and myself.
>
> regards
>
> Keith
>

---

From: Scott Lawrence <[email-masked]>
Date: Thu, 08 Jun 2006 11:12:20 -0400

> I think it still has at least one serious question open - that being  

Or more generally, does it help more than it harms?  Diagnosing bad
routing can be a real pain - can you imagine running a network without
traceroute?

> response that did not have the debugging information.

In experiments at SIPit we found that all the proxies tested clamped the
hop limit to 20 (no one knew why this value was apparently independently
chosen by all of them - it was quite a surprise), so it does not seem
likely that anything is going to get to 70 hops (why was such a large
value chosen - it seems wildly unlikely to me that it would ever be
needed in a scenario that results in success).

There is advice in the draft on how to select Vias to be returned if
want to limit the size of the response (which might be dependent on the
transport).  Are you suggesting that something stronger is needed?

-- 
Scott Lawrence  tel:+1-781-938-5306;ext=162 or sip:[email-masked]
  sipXpbx project coordinator - SIPfoundry    http://www.sipfoundry.org/sipX
  Chief Architect             - Pingtel Corp. http://www.pingtel.com/