Re: [mdnsext] WG Review: Extensions for Scalable DNS Service Discovery (dnssd)

Tim Chown <> Thu, 03 October 2013 18:52 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 11AD021F8D62; Thu, 3 Oct 2013 11:52:06 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.598
X-Spam-Status: No, score=-2.598 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, HTML_MESSAGE=0.001]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id qYpzdwZq6bDc; Thu, 3 Oct 2013 11:51:51 -0700 (PDT)
Received: from ( [IPv6:2001:630:d0:f102::25e]) by (Postfix) with ESMTP id F2C3021F8984; Thu, 3 Oct 2013 11:43:36 -0700 (PDT)
Received: from (localhost []) by (8.13.8/8.13.8) with ESMTP id r93IhUjm025455; Thu, 3 Oct 2013 19:43:30 +0100
X-DKIM: Sendmail DKIM Filter v2.8.2 r93IhUjm025455
DKIM-Signature: v=1; a=rsa-sha1; c=simple/simple;; s=201304; t=1380825810; bh=SXHCY0EZOq8r7Nj75r+vIh08TRE=; h=Mime-Version:Subject:From:In-Reply-To:Date:Cc:References:To; b=NSs5dihBz9bfSTNDxdWxzh6rfqfmSGHaa6AlFhqio/w74KdGwTkYb7rf+jZLXSebq Mpteu7h18+wbsZ3SWet31Vhneol8gCfNFL1qOInKxu71QSaNC+d654ffrZxKH/Nz8Q duelj2QUfvzDTYK2Wd6qUxJHHkwYjwOVDanvYrjY=
Received: from ([2001:630:d0:f102:250:56ff:fea0:401]) by ( [2001:630:d0:f102:250:56ff:fea0:68da]) envelope-from <> with ESMTP (valid=N/A) id p92JhU0544563631dS ret-id none; Thu, 03 Oct 2013 19:43:30 +0100
Received: from [] ( []) (authenticated bits=0) by (8.13.8/8.13.8) with ESMTP id r93IhO3B031347 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Thu, 3 Oct 2013 19:43:25 +0100
Content-Type: multipart/alternative; boundary="Apple-Mail=_2193BD6E-6B92-4549-A4F3-42F75A2BC089"
Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\))
From: Tim Chown <>
In-Reply-To: <>
Date: Thu, 3 Oct 2013 19:43:24 +0100
Message-ID: <EMEW3|db89e71161b3bb8f7117f7d83e2ef53ep92JhU03tjc||>
References: <> <> <>
To: manning bill <>
X-Mailer: Apple Mail (2.1510)
X-ECS-MailScanner: Found to be clean, Found to be clean
X-smtpf-Report: sid=p92JhU054456363100; tid=p92JhU0544563631dS; client=relay,forged,no_ptr,ipv6; mail=; rcpt=; nrcpt=6:0; fails=0
X-ECS-MailScanner-Information: Please contact the ISP for more information
X-ECS-MailScanner-ID: r93IhUjm025455
Cc: " mdnsext" <>, Lemon Ted <>, "<> Discussion" <>, IETF-Announce <>, Ralph Droms <>
Subject: Re: [mdnsext] WG Review: Extensions for Scalable DNS Service Discovery (dnssd)
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: "Discussion of extensions to Bonjour \(mDNS and DNS-SD\) for routed networks." <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Thu, 03 Oct 2013 18:52:06 -0000

On 3 Oct 2013, at 18:07, manning bill <> wrote:

>  ----- The following addresses had permanent fatal errors -----
> <>
>   (reason: 550 5.1.1 <>rg>: Recipient address rejected: User unknown in virtual alias table)

I think the active list is still

And the 'header' information below should now probably read something like this:

--- snip ---

Scalable DNS Service Discovery  (dnssd)
Current Status: Proposed WG

 Ralph Droms <>
 Tim Chown <>

Assigned Area Director:
 Ted Lemon <>

Mailing list
 To Subscribe:
 Pre-WG BoF Archive: 

--- snip ---


> On 3October2013Thursday, at 8:42, The IESG wrote:
>> A new IETF working group has been proposed in the Internet Area. The IESG
>> has not made any determination yet. The following draft charter was
>> submitted, and is provided for informational purposes only. Please send
>> your comments to the IESG mailing list (iesg at by 2013-10-10.
>> Extensions for Scalable DNS Service Discovery  (dnssd)
>> ------------------------------------------------
>> Current Status: Proposed WG
>> Chairs:
>> Ralph Droms <>
>> Tim Chown <>
>> Assigned Area Director:
>> Ted Lemon <>
>> Mailing list
>> Address:
>> To Subscribe:
>> Archive:
>> Charter:
>> Background
>> ----------
>> Zero configuration networking protocols are currently well suited to
>> discover services within the scope of a single link.  In particular,
>> the DNS-SD [RFC 6763] and mDNS [RFC6762] protocol suite (sometimes
>> referred to using Apple Computer Inc.'s trademark, Bonjour) are
>> widely used for DNS-based service discovery and host name resolution
>> on a single link.
>> The DNS-SD/mDNS protocol suite is used in many scenarios including
>> home, campus, and enterprise networks.  However, the zero configuration
>> mDNS protocol is constrained to link-local multicast scope by design,
>> and therefore cannot be used to discover services on remote links.
>> In a home network that consists of a single (possibly bridged) link,
>> users experience the expected discovery behavior; available services
>> appear because all devices share a common link.  However, in multi-link
>> home networks (as envisaged by the homenet WG) or in routed campus or
>> enterprise networks, devices and users can only discover services on
>> the same link, which is a significant limitation.  This has led to
>> calls, such as the Educause petition, to develop an appropriate service
>> discovery solution to span multiple links or to perform discovery across
>> a wide area, not necessarily on directly connected links.
>> In addition, the "Smart Energy Profile 2 Application Protocol Standard",
>> published by ZigBee Alliance and HomePlug Powerline Alliance specifies
>> the DNS-SD/mDNS protocol suite as the basis for its method of zero
>> configuration service discovery.  However, its use of wireless mesh
>> multi-link subnets in conjunction with traditional routed networks will
>> require extensions to the DNS-SD/mDNS protocols to allow operation
>> across multiple links.
>> The scenarios in which multi-link service discovery is required may
>> be zero configuration environments, environments where administrative
>> configuration is supported, or a mixture of the two.
>> As demand for service discovery across wider area routed networks
>> grows, some vendors are beginning to ship proprietary solutions.  It
>> is thus both timely and important that efforts to develop improved, 
>> scalable, autonomous service discovery solutions for routed networks 
>> are coordinated towards producing a single, standards-based solution.
>> The WG will consider the tradeoffs between reusing/extending existing
>> protocols and developing entirely new ones.  It is highly desirable
>> that any new solution is backwardly compatible with existing DNS-SD/mDNS
>> deployments.  Any solution developed by the dnssd WG must not conflict
>> or interfere with the operation of other zero-configuration service and
>> naming protocols such as uPnP or LLMNR.  Integration with such protocols
>> is out of scope for this WG.
>> The focus of the WG is to develop a solution for extended, scalable 
>> DNS-SD.  This work is likely to highlight problems and challenges with 
>> naming protocols, as some level of coexistence will be required between 
>> local zero configuration name services and those forming part of the 
>> global DNS.  It is important that these issues are captured and 
>> documented for further analysis; solving those problems is however not 
>> within the scope of this WG.
>> Working Group Description
>> -------------------------
>> To that end, the primary goals of the dnssd WG are as follows:
>> 1. To document a set of requirements for scalable, autonomous
>>  DNS-based service discovery in routed, multi-link networks in the
>>  following five scenarios:
>>  (A) Personal Area networks, e.g., one laptop and one printer.
>>      This is the simplest example of a service discovery network,
>>      and may or may not have external connectivity. 
>>  (B) Home networks, as envisaged by the homenet WG, consisting of 
>>      one or more exit routers, with one or more upstream providers 
>>      or networks, and an arbitrary internal topology with 
>>      heterogeneous media where routing is automatically configured. 
>>      The home network would typically be a single zero configuration 
>>      administrative domain with a relatively limited number of 
>>      devices. 
>>  (C) Wireless 'hotspot' networks, which may include wireless networks
>>      made available in public places, or temporary or permanent
>>      infrastructures targeted towards meeting or conference style
>>      events, e.g., as provided for IETF meetings.  In such
>>      environments other devices may be more likely to be 'hostile'
>>      to the user.
>>  (D) Enterprise networks, consisting of larger routed networks, 
>>      with large numbers of devices, which may be deployments 
>>      spanning over multiple sites with multiple upstreams, and
>>      one more more administrative domains (depending on internal
>>      administrative delegation).  The large majority of the 
>>      forwarding and security devices are configured.  These may
>>      be commercial or academic networks, with differing levels 
>>      of administrative control over certain devices on the network,
>>      and BYOD devices commonplace in the campus scenario.
>>  (E) Mesh networks such as RPL/6LoWPAN, with one or more links per
>>      routable prefix, which may or may not have external connectivity.
>>      The topology may use technologies including 802.11 wireless, 
>>      HomePlug AV and GP, and ZigBee IP. 
>>  In the above scenarios, the aim is to facilitate service discovery 
>>  across the defined site.  It is also desirable that a user or device, 
>>  when away from such a site, is still able to discover services 
>>  within that site, e.g. a user discovering services in their home 
>>  network while remote from it.
>>  It is also desirable that multiple discovery scopes are supported,
>>  from the point of view of announcements and discovery, be the
>>  scope 'site', 'building', or 'room'.  A user for example may only
>>  be interested in devices in the same room.
>> 2. To develop an improved, scalable solution for service discovery 
>>  that can operate in multi-link networks, where devices may be
>>  in neighboring or non-neighboring links, applicable to
>>  the scenarios above.  The solution will consider tradeoffs between
>>  reusing/extending existing protocols and developing entirely new
>>  protocols. 
>>  The solution should include documentation or definition of the
>>  interfaces that can be implemented, separately to transport of 
>>  the information.
>> 3. To document challenges and problems encountered in the coexistence 
>>  of zero configuration and global DNS name services in such 
>>  multi-link networks, including consideration of both the name 
>>  resolution mechanism and the namespace.
>> It is important that the dnssd WG takes input from stakeholders in
>> the scenarios it is considering.  For example, the homenet WG is
>> currently evaluating its own requirements for naming and service
>> discovery; it is up to the homenet WG as to whether it wishes to
>> recommend adoption of the solution developed in the dnssd WG, but
>> coordination between the WGs is desirable.
>> Deliverables:
>> The WG will produce three documents: an Informational RFC on the
>> requirements for service discovery protocols operating on potentially
>> non-neighboring multi-link networks as described above; a Standards
>> Track RFC documenting an extended, scalable service discovery solution 
>> that is applicable to those scenarios; and an Informational RFC 
>> describing the problems arising when developing the extended SD solution 
>> and how it affects the integration of local zero configuration and global
>> DNS name services.
>> Milestones:
>> Sep 2013 - Formation of the WG
>> Oct 2013 - Adopt requirements draft as WG document
>> Jan 2014 - Submit requirements draft to the IESG as an Informational
>> RFC
>> Mar 2014 - Adopt wide-area service discovery solution draft as WG
>> document 
>> Mar 2014 - Adopt Informational document on the problems and challenges
>> arising for zeroconf and unicast DNS name services
>> Sep 2014 - Submit wide-area service discovery solution draft to the
>> IESG as Standards Track RFC 
>> Sep 2014 - Submit the zeroconf and unicast DNS "problems and
>> challenges" draft to the IESG as Informational.