Re: [mdnsext] The Scope Swamp: Wireless Considerations

"Bhavik Fajalia (bfajalia)" <> Wed, 07 August 2013 03:50 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id B39FD21F9D7A for <>; Tue, 6 Aug 2013 20:50:42 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -8.846
X-Spam-Status: No, score=-8.846 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, MIME_BASE64_TEXT=1.753, RCVD_IN_DNSWL_HI=-8]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id Kha4G2460REr for <>; Tue, 6 Aug 2013 20:50:38 -0700 (PDT)
Received: from ( []) by (Postfix) with ESMTP id 2026021F9ACA for <>; Tue, 6 Aug 2013 20:50:38 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple;;; l=4090; q=dns/txt; s=iport; t=1375847438; x=1377057038; h=from:to:subject:date:message-id:in-reply-to:content-id: content-transfer-encoding:mime-version; bh=wARVM9Ep9E35WotuAqub6vVqWg9YDOnKj1OtQAsmKX4=; b=BapTKXOXBADkLXO0TWFAAbMuCy8d6Vvx5SA7MjUt63IjcyofjvVME+n6 AaHxMGIu2jAUKVGtOnB2tsAQjFC2L+kR4UGV8jMz5dE7bhzss18vc7q0d w6STWzWG2hrtRxaaL+VKcQm6WcDrvcjEyNqVr7SLe7ksNYajZmJF5q+B4 U=;
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-AV: E=Sophos;i="4.89,830,1367971200"; d="scan'208";a="244375660"
Received: from ([]) by with ESMTP; 07 Aug 2013 03:50:37 +0000
Received: from ( []) by (8.14.5/8.14.5) with ESMTP id r773obu5011607 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=FAIL); Wed, 7 Aug 2013 03:50:37 GMT
Received: from ([]) by ([]) with mapi id 14.02.0318.004; Tue, 6 Aug 2013 22:50:37 -0500
From: "Bhavik Fajalia (bfajalia)" <>
To: "Yi Yang (yiya)" <>, Alf Watt <>, "" <>
Thread-Topic: [mdnsext] The Scope Swamp: Wireless Considerations
Thread-Index: AQHOkiVfwNYZDvz0TEi43x6OJpyGy5mIqLkAgAEljIA=
Date: Wed, 7 Aug 2013 03:50:36 +0000
Message-ID: <>
In-Reply-To: <>
Accept-Language: en-US
Content-Language: en-US
user-agent: Microsoft-MacOutlook/
x-originating-ip: []
Content-Type: text/plain; charset="euc-kr"
Content-ID: <>
Content-Transfer-Encoding: base64
MIME-Version: 1.0
Subject: Re: [mdnsext] The Scope Swamp: Wireless Considerations
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: Wed, 07 Aug 2013 03:50:42 -0000

I agree with this. You might want to go through the draft
Which mentions how wireless is different from wired and what are the
optimisations needed for wireless network.

Apart from scope, we need to worry about the the amount of mDNS traffic
goes to wireless clients,
it would not only impact the shared bandwidth but also battery power of
the wireless devices.


On 07/08/13 1:19 AM, "Yi Yang (yiya)" <> wrote:

>I agree we must consider difference between wired/wireless networks.
>Actually, even for a smaller scope, multicast over 802.11 is still an
>expensive operation.
>On the other hand, we should de-couple discovery scope from
>broadcast/multicast domain.
>On 8/5/13 5:47 PM, "Alf Watt" <> wrote:
>>Following up from the BoF discussion in Berlin today on scoping of
>>The discussion of scope needs to acknowledge the difference between wired
>>and wireless networks.
>>In all IP networks the size of the broadcast domain is a fundamental
>>limitation, as the number of devices on the link increases the broadcast
>>traffic begins to consume a larger and larger percentage of the available
>>bandwidth. Traditionally large wired networks were segmented along
>>physical lines, by floor or wing, for example, with each area being
>>assigned a subnet and routed to provide end-to-end connectivity.
>>Wi-Fi users expect (and the 802.11 protocol requires) that users on a
>>single SSID are connected to the same IP network and broadcast domain so
>>that they can roam seamlessly anywhere within a particular ESS (which can
>>be a building, campus or metro area). Limiting the size of these
>>domains means separating users onto different Wi-Fi networks depending on
>>their role, instead of their location.
>>So for wired networks we have a natural, physical scope depending on the
>>physical connection of hosts, in wireless networks we have scopes which
>>depend largely on the users access rights (since Wi-Fi is almost always
>>the security demarkation in networks).
>>It¹s also worth nothing that the BCP for broadcast domain size is only
>>hosts (a /24) which makes the 802.11 ESS requirement for a single
>>broadcast domain behind a given ESS difficult to achieve for large
>>networks, which is why many Wi-Fi vendors support multicast filtering,
>>client isolation and ARP proxies all of which can impact mDNS usability.
>>mdnsext mailing list
>mdnsext mailing list