oyvindskaaden
/
glados.no
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity
glados.no/_files/sound/bss/london/manual/MAIN/AVB.htm

805 lines
47 KiB
HTML
Raw Normal View History

Add files
2020-08-16 15:32:44 +02:00
<!doctype HTML public "-//W3C//DTD HTML 4.0 Frameset//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
<meta name="generator" content="Adobe RoboHelp 9">
<title>AVB</title>
<link rel="StyleSheet" href="HtmlHelp.css" type="text/css">
<style title="hcp" type="text/css">
<!--
p.hcp1 { font-size:10pt; }
i.hcp2 { font-style:italic; }
ul.hcp3 { font-family:Arial, sans-serif;
color:#000000; }
li.hcp4 { list-style:none;
display:inline;
font-family:Arial, sans-serif;
color:#000000;
font-size:10pt; }
img.hcp5 { border:none; }
p.hcp6 { mso-margin-top-alt:auto;
mso-margin-bottom-alt:auto;
line-height:115%;
font-family:Arial, sans-serif;
font-size:10pt;
mso-bidi-font-family:Calibri;
color:#000000; }
span.hcp7 { line-height:115%;
font-family:Arial, sans-serif; }
span.hcp8 { mso-bidi-font-size:12.0pt;
line-height:115%;
font-family:Arial, sans-serif; }
p.hcp9 { font-family:Arial, sans-serif;
font-size:10pt;
color:#000000; }
span.hcp10 { mso-ansi-language:EN-GB; }
b.hcp11 { font-weight:bold; }
li.hcp12 { font-family:Arial, sans-serif;
font-size:10pt;
color:#000000; }
span.hcp13 { mso-list:l0 level1 lfo2;
tab-stops:list 18.0pt;
mso-ansi-language:EN-GB; }
span.hcp14 { font-size:12.0pt;
font-family:"Times New Roman" , serif;
mso-ansi-language:EN-GB;
font-weight:bold; }
span.hcp15 { font-size:12.0pt;
font-family:"Times New Roman" , serif;
mso-ansi-language:EN-GB; }
span.hcp16 { font-weight:bold; }
span.hcp17 { font-style:italic;
font-weight:bold; }
span.hcp18 { mso-spacerun:yes; }
p.hcp19 { mso-ansi-language:EN-GB;
color:#000000;
font-family:Arial, sans-serif;
font-size:10pt; }
p.hcp20 { mso-ansi-language:EN-GB;
font-family:Arial, sans-serif;
font-size:10pt;
margin-left:40px; }
p.hcp21 { mso-ansi-language:EN-GB;
color:#000000;
font-family:Arial, sans-serif;
font-size:10pt;
font-weight:bold; }
span.hcp22 { mso-ascii-font-family:Calibri;
mso-fareast-font-family:Calibri;
mso-hansi-font-family:Calibri;
mso-bidi-font-family:Times New Roman;
font-weight:normal; }
span.hcp23 { font-weight:normal; }
h4.hcp24 { mso-ansi-language:EN-GB; }
span.hcp25 { mso-ansi-language:EN-GB;
mso-ascii-font-family:Calibri;
mso-fareast-font-family:Calibri;
mso-hansi-font-family:Calibri;
mso-bidi-font-family:Times New Roman;
font-weight:normal; }
span.hcp26 { mso-ascii-font-family:Calibri;
mso-fareast-font-family:Calibri;
mso-hansi-font-family:Calibri;
mso-bidi-font-family:Times New Roman;
mso-ansi-language:EN-GB; }
-->
</style>
</head>
<body>
<h1 class="firstHeading">AVB Network Card</h1>
<div id="content">
<div id="bodyContent">
<p id="siteSub">&#160;<script type="text/javascript" language="JavaScript1.2">//<![CDATA[
if (window.showTocToggle) { var tocShowText = "show"; var tocHideText = "hide"; showTocToggle(); }
//]]></script></p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Overview" id="Overview"></a></p>
<h2>AVB Overview</h2>
<p class="hcp1"><span lang="EN-US" xml:lang="EN-US">The
Soundweb London BLU-805 and BLU-325 are capable of sending and
receiving Ethernet AVB audio. &#160;AVB, or Audio/Video Bridging,
is a common name for a set of IEEE standards that ensure the transmission
of high quality streaming audio and video over a standard Ethernet
connection.</span></p>
<p class="hcp1"><i class="hcp2"><span
lang="EN-US" xml:lang="EN-US">Note: Soundweb London devices cannot
send, receive, or process video data.</span></i></p>
<p class="hcp1"><span lang="EN-US" xml:lang="EN-US">As
a networked audio transport, AVB is similar to <a href="Cobranet&#32;Information.html">CobraNet</a>
in many ways, with a few key differences:</span></p>
<ul type="disc" class="hcp3">
<li class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-list: l0 level1 lfo1; tab-stops: list 36.0pt; font-family: Arial, sans-serif;
color: #000000; font-size: 10pt;"><p class="hcp1"><span
lang="EN-US" xml:lang="EN-US">Non-proprietary, based on open
standards</span></p></li>
<li class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-list: l0 level1 lfo1; tab-stops: list 36.0pt; font-family: Arial, sans-serif;
color: #000000; font-size: 10pt;"><p class="hcp1"><span
lang="EN-US" xml:lang="EN-US">Guaranteed delivery of media</span></p></li>
<li class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-list: l0 level1 lfo1; tab-stops: list 36.0pt; font-family: Arial, sans-serif;
color: #000000; font-size: 10pt;"><p class="hcp1"><span
lang="EN-US" xml:lang="EN-US">No need to specify <20>multicast<73>
or <20>unicast<73> transmissions. Any transmitted AVB stream can
have 1 or more receivers. Unlike CobraNet multicast bundles,
AVB streams with multiple receivers will only transmit to
those receivers, and they will <i style="mso-bidi-font-style: normal;">not</i>
needlessly broadcast across the entire network</span></p></li>
<li class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-list: l0 level1 lfo1; tab-stops: list 36.0pt; font-family: Arial, sans-serif;
color: #000000; font-size: 10pt;"><p class="hcp1"><span
lang="EN-US" xml:lang="EN-US">Simplified network switch management
due to the above three bullets</span></p></li>
<li class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-list: l0 level1 lfo1; tab-stops: list 36.0pt; font-family: Arial, sans-serif;
color: #000000; font-size: 10pt;"><p class="hcp1"><span
lang="EN-US" xml:lang="EN-US">Reduced latency</span></p></li>
<li class="hcp4"><ul style="font-family: Arial, sans-serif;
color: #000000;
font-size: 10pt;"
type="circle">
<li class="MsoNormal" style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; mso-list: l0 level2 lfo1;
tab-stops: list 72.0pt; font-family: Arial, sans-serif;
color: #000000; font-size: 10pt;"><p class="hcp1"><span
lang="EN-US" xml:lang="EN-US">Latency range for CobraNet
in Soundweb London: 1.33ms <20> 5.33ms</span></p></li>
<li class="MsoNormal" style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; mso-list: l0 level2 lfo1;
tab-stops: list 72.0pt; font-family: Arial, sans-serif;
color: #000000; font-size: 10pt;"><p class="hcp1"><span
lang="EN-US" xml:lang="EN-US">Latency range for AVB in
Soundweb London: </span><span lang="EN-US" xml:lang="EN-US"
style="mso-tab-count: 1;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;</span><span
lang="EN-US" xml:lang="EN-US">&#160;0.5ms <20> 2.0ms</span></p></li>
</ul></li>
<li class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-list: l0 level1 lfo1; tab-stops: list 36.0pt; font-family: Arial, sans-serif;
color: #000000; font-size: 10pt;"><p style="mso-ansi-language: IT;
font-size: 10pt;"><span
lang="IT" xml:lang="IT">Increased audio I/O capability per
device</span></p></li>
<li class="hcp4"><ul type="circle" class="hcp3">
<li class="MsoNormal" style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; mso-list: l0 level2 lfo1;
tab-stops: list 72.0pt; font-family: Arial, sans-serif;
color: #000000; font-size: 10pt;"><p class="hcp1"><span
lang="EN-US" xml:lang="EN-US">Max CobraNet audio channels
in Soundweb London: 32x32 per device</span></p></li>
<li class="MsoNormal" style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; mso-list: l0 level2 lfo1;
tab-stops: list 72.0pt; font-family: Arial, sans-serif;
color: #000000; font-size: 10pt;"><p class="hcp1"><span
lang="EN-US" xml:lang="EN-US">Max AVB audio channels in
Soundweb London: 64x64 per device</span></p></li>
</ul></li>
</ul>
<p><span lang="EN-US" xml:lang="EN-US">The AVB standards were created
through a consortium of industry experts which was then ratified
and accepted by the IEEE industry standards body. This means that
AVB is not just another proprietary non-standard protocol that
floats on top of the Ethernet layers. AVB is the Ethernet. The
big difference between AVB and previous solutions for network
streamed media (such as CobraNet) is that the IEEE controls the
Ethernet standards, which allowed for the specifications of not
just the endpoints, but more importantly the switches. This allows
an entire network to be designed to accommodate audio and video,
with compatibility between AVB devices that are made by different
manufacturers.</span></p>
<p><span lang="EN-US" xml:lang="EN-US">The standards specify a
means to provide time synchronized low latency audio and video
over standard CAT5e cable. The majority of the bandwidth across
the network is reserved to carry audio and video, and to guarantee
the arrival of a signal</span></p>
<p><span lang="EN-US" xml:lang="EN-US">.<img src="75&#32;bandwidth&#32;reserved.jpg" alt="" width="332" height="157" border="0" class="hcp5"></span></p>
<p class="hcp6">&#160;</p>
<p class="hcp6"><span lang="EN-US"
xml:lang="EN-US">In order to accomplish transporting the large
amount of information required by both audio and video across
a network, bandwidth is reserved and defended throughout the network
by the switches. By default the switch will reserve and defend
75% of network bandwidth to be exclusively used for AVB media,
both audio and video. This will guarantee precisely synchronized
audio/video without interruption from non-time sensitive data
and communication, such as email or control protocol traffic (also
known as <20>Best Effort<72> traffic). By design, the switch will not
allow for the audio or video to become corrupted.</span></p>
<p class="hcp1"><span lang="EN-US" xml:lang="EN-US" class="hcp7">Each
audio/video sample is time-stamped with exactly what time to play,
and a</span><span lang="EN-US" xml:lang="EN-US" class="hcp8">ll
AVB devices are synchronized to a common clock known as the Grand
Master clock.</span> <span lang="EN-US" xml:lang="EN-US" class="hcp8">This
allows for the synchronization of multiple streams of audio and
video to be rendered at</span> <span lang="EN-US" xml:lang="EN-US" class="hcp7">the
correct time with respect to each other.</span></p>
<p class="hcp9"><span
lang="EN-US" xml:lang="EN-US">An AVB network inherently supports
multiple simultaneous sample rates and (sample) clock sources
which allow video and audio streams to be synchronized even though
they travel on different paths with different sample rates.</span></p>
<p style="line-height: 115%; font-family: Arial, sans-serif; font-size: 10pt;
color: #000000;"><span lang="EN-US" xml:lang="EN-US">Details
for the six IEEE audio/video bridging standards (802.1AS, 8021.Qat,
802.1Qav, 802.1BA, 1722, and 1733) are available at <a href="http://www.ieee.org/index.html">IEEE.org</a>
and <a href="http://www.avnu.org/">AVnu.org</a></span></p>
<p>&#160;</p>
<h2>Soundweb London AVB Module</h2>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-family: Arial, sans-serif; font-size: 10pt;"><span class="hcp10">T</span><span
lang="EN-US" xml:lang="EN-US">he <a href="BLU-805.htm">BLU-805</a>
and <a href="BLU-325.htm">BLU-325</a> devices are fitted with
an AVB module. The module offers a Primary and a Secondary AVB
port. Under normal operation, only the Primary port transmits
and receives data to and from the network. Should the Primary
port or connection fail, the AVB module automatically switches
to receive from and transmit with the Secondary port. This must
be considered in the network design. It may be appropriate to
connect the Primary AVB port to a Primary network and the Secondary
AVB port to a Secondary, backup network. In this event, it should
be noted that the backup network should in some way be bridged
to the Primary network in order for the audio data to be present
on the Secondary network should the module switch over.</span></p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-family: Arial, sans-serif; font-size: 10pt;"><i class="hcp2"><span class="hcp10">NOTE:</span></i> <i><span class="hcp10">The
secondary port is not currently enabled. &#160;It will be enabled
in a future release of HiQnet London Architect.</span></i></p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Hardware_Configuration" id="Hardware_Configuration"></a></p>
<h2>Network Connections</h2>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 10pt; font-family: Arial, sans-serif;"><span lang="EN-US"
xml:lang="EN-US">Devices can only be connected together through
switches which support AVB. Examples of such switches are the
BSS Audio / NETGEAR GS724T Ethernet Switch or the LABX Titanium
411 Ruggedized AVB Ethernet Bridge Switch. Do not connect the
AVB ports to any switch which does not support AVB.</span></p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 10pt; font-family: Arial, sans-serif;"><span lang="EN-US"
xml:lang="EN-US">The AVB devices can be wired in London Architect
as shown.</span></p>
<p><img src="AVB&#32;connections.jpg" alt="" border="0" class="hcp5"></p>
<p>&#160;<br>
<span lang="EN-US" xml:lang="EN-US" style="font-size: 10pt; font-family: Arial, sans-serif;">Note
that the standard Ethernet ports (labeled <20>Control<6F> in London
Architect) must also be physically connected to ensure communication
between the devices. In the same way that Soundweb London CobraNet
ports send and receive audio only (not control data), the Soundweb
London AVB ports send and receive audio only.</span></p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 10pt; font-family: Arial, sans-serif;"><span lang="EN-US"
xml:lang="EN-US">In 2-device systems, it is possible to connect
the AVB ports directly together, as shown</span></p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 10pt; font-family: Arial, sans-serif;"><span lang="EN-US"
xml:lang="EN-US">.</span><img src="2&#32;device&#32;system.jpg" alt="" border="0" class="hcp5"></p>
<h2>Cable Requirements</h2>
<p class="hcp9"><span
lang="EN-US" xml:lang="EN-US">CAT5e or better cable may be used,
allowing cable runs of up to 100m per connection. If more distance
is required, Gigabit fiber converters<72>such as the BLU-MC1<43>can
be used. 100Mb (<28>Fast Ethernet<65>) fiber converters <i style="mso-bidi-font-style: normal;
font-weight: bold;">cannot</i> be used for the Soundweb London
AVB ports, because they are Gigabit ports.</span></p>
<h2><b class="hcp11"><a name="AVB_Audio_Channels_per_Device"></a>AVB
Audio Channels per Device</b></h2>
<h3>Audio channel rules</h3>
<ul type="disc">
<ul type="disc">
<li class="hcp12"><p class="MsoNormal" style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; text-indent: -18.0pt;
font-family: Arial, sans-serif;
font-size: 10pt; margin-left: 0px;"><span class="hcp13">The Soundweb London AVB</span><span
style="mso-list: l0 level1 lfo2; tab-stops: list 18.0pt;">
</span><span class="hcp13">module can
transmit 64 channels and receive 64 channels <b style="mso-bidi-font-weight: normal;
font-weight: normal;">simultaneously</b> </span><span class="hcp13">(64x64). &#160;</span></p></li>
<li class="hcp12"><p class="MsoNormal" style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo2;
tab-stops: list 18.0pt; text-indent: -18.0pt;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;">The card cannot
transmit more than 64 channels or receive more than 64
channels in total.</p></li>
</ul>
</ul>
<h3>Stream rules:</h3>
<ul type="disc">
<li><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
margin-left: 18.0pt; text-indent: -18.0pt; mso-list: l1 level1 lfo1;
tab-stops: list 18.0pt; font-family: Arial, sans-serif;
font-size: 10pt;"><span class="hcp10">An
AVB stream may contain between 1 and 32 channels (inclusive).</span></p></li>
<li><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
margin-left: 18.0pt; text-indent: -18.0pt; mso-list: l1 level1 lfo1;
tab-stops: list 18.0pt; font-family: Arial, sans-serif;
font-size: 10pt;"><span class="hcp10">Each
AVB card can transmit up to 64 streams</span></p></li>
<li><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
margin-left: 18.0pt; text-indent: -18.0pt; mso-list: l1 level1 lfo1;
tab-stops: list 18.0pt; font-family: Arial, sans-serif;
font-size: 10pt; mso-ansi-language: EN-GB;">Each AVB
card can receive up to 62 streams with a further 2 streams
reserved for MCN</p></li>
</ul>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
margin-left: 40px; text-indent: -40px;"><span class="hcp14">Talker
(Transmit)</span></p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
margin-left: 40px; text-indent: -40px;"><span class="hcp14">Example</span><span class="hcp15"> </span><span class="hcp14">A</span><span class="hcp15">:</span> <span class="hcp15">2
streams of 32 channels</span></p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-ansi-language: EN-GB; margin-left: 40px; text-indent: -40px;"><span class="hcp16">Example</span> <span class="hcp16">B</span>:
32 streams of 2 channels</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-ansi-language: EN-GB; margin-left: 40px; text-indent: -40px;"><span class="hcp16">Example</span> <span class="hcp16">C</span>:
29 streams of 2 channels, plus 1 stream of 5 channels plus 1 stream
of 1 channel</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-ansi-language: EN-GB; margin-left: 40px; text-indent: -40px;"><span class="hcp16">Example</span> <span class="hcp16">D</span>:
61 streams of 1 channel plus 1 stream of 3 channels</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-ansi-language: EN-GB; margin-left: 40px; text-indent: -40px;"><span class="hcp16">Example E</span>: 64 streams of 1 channel</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-ansi-language: EN-GB; margin-left: 40px; text-indent: -40px;
font-weight: bold;">Listener (Receive)</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
margin-left: 40px; text-indent: -40px;"><span class="hcp16">Example
A</span>: 2 streams of 32 channels</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-ansi-language: EN-GB; margin-left: 40px; text-indent: -40px;"><span class="hcp16">Example</span> <span class="hcp16">B</span>:
32 streams of 2 channels</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-ansi-language: EN-GB; margin-left: 40px; text-indent: -40px;"><span class="hcp16">Example</span> <span class="hcp16">C</span>:
29 streams of 2 channels, plus 1 stream of 5 channels plus 1 stream
of 1 channel</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-ansi-language: EN-GB; margin-left: 40px; text-indent: -40px;"><span class="hcp16">Example</span> <span class="hcp16">D</span>:
61 streams of 1 channel plus 1 stream of 3 channels</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-ansi-language: EN-GB; margin-left: 40px; text-indent: -40px;"><span class="hcp16">Example E</span>: 62 streams of 1 channel</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-ansi-language: EN-GB;">There are thousands of permutations
as long as the total number of channels transmitted is 64 or less.
Similarly, the total number of channels received must be 64 or
less.</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-ansi-language: EN-GB;"><span class="hcp17">Note:
It is advised to configure and use (multi-channel streams) vs.
(single channel streams). This is the most efficient transport
method for transmitting and/or receiving</span><span style="mso-spacerun: yes;
font-style: italic; font-weight: bold;">&#160;</span><span class="hcp17">&#160;AVB audio channels across a network
switch.</span><span class="hcp18">&#160;&#160;</span></p>
<h3 style="font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-GB;"><span
style="mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"><a
href="MAINCompiling.htm">Resource Meter</a></span></h3>
<span style="font-size: 12.0pt; font-family: 'Times New Roman', serif;
mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-GB;
mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">The
configuration view of a BLU-805 or BLU-325 contains a second resource
meter which displays the AVB resources only. This AVB resource
meter shows the % of streams and channels used for a particular
configuration</span> as shown below.
<p><img src="AVB&#32;resource&#32;meter.jpg" alt="" border="0" class="hcp5"></p>
<p class="hcp19">In the above example, 32 AVB input channels
are enabled, and 32 AVB output channels are enabled. 32x32 is
exactly half of the BLU device<63>s AVB I/O capability. Therefore
50% is displayed in the AVB resource meter (which is the same
shade of purple as the AVB input/output objects). &#160;</p>
<p class="hcp19">In a design where, for example, 32 AVB input
channels are enabled,<span class="hcp17">
</span>&#160;50% will still be displayed even though no output
channels have been enabled. As output channels are enabled the
resource meter will continue to display 50% until the number of
outputs channels enabled exceeds 32.</p>
<p class="hcp19">In a design where, for example, 33 AVB input
channels are enabled and no AVB<span class="hcp17"> </span>output
channels are enabled then 51% will be displayed on the resource
meter. &#160;Again as output channels are enabled the resource
meter will continue to display 50% until the number of outputs
channels enabled exceeds 32.</p>
<p class="hcp19">The above examples also apply to the resource
meter where it is the output channels which have been assigned.</p>
<h2><b class="hcp11">Creating Streams</b></h2>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;">In the <a href="MAINConfiguration_Window.htm">configuration
window</a> of a BLU-805 and a BLU-325, by default there is one
AVB Input processing object (Rx, Listener) and one AVB Output
processing object (Tx, Talker). &#160;Initially they have no nodes
on them.</p>
<p class="MsoNormal" style="mso-ansi-language: EN-GB; mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; font-family: Arial, sans-serif;
font-size: 10pt;"><img src="AVB&#32;Files/Listener.PNG" alt="" border="0" class="hcp5">
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<img src="AVB&#32;Files/Talker.PNG" alt="" border="0" class="hcp5"></p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;">You can add or remove as many AVB processing
objects as you wish inside a BLU-805 and BLU-325 although the
<a href="AVB.htm#AVB_Audio_Channels_per_Device">number of streams</a>
is limited as described.</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;">Streams are defined system-wide. They can
be created using the dialog which can be accessed in several ways:</p>
<ul type="disc">
<li><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;">The <a href="System&#32;Menu.html">System
Menu</a> - <20>System-&gt;AVB Streams...<2E> </p></li>
<li><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;">When creating a new AVB Input or
Output object - the dialog pops up when the object is created</p></li>
<li><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;">By opening the dialog from the AVB
input or output properties by clicking on an AVB Input or
Output object, then accessing the Stream ID parameter from
the properties.</p></li>
</ul>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;"><img src="AVB&#32;Files/StreamDialog.PNG" alt="" border="0" class="hcp5"></p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;">Use the above dialog to view details of,
add, delete and edit streams. &#160;</p>
<h3>Define AVB Stream</h3>
<p>Click on the 'NEW' button to open the 'Define AVB Stream' dialog
shown below.</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;"><span lang="EN-US" xml:lang="EN-US"><img src="AVB&#32;Files/Define_Stream.PNG" alt="" border="0" class="hcp5"></span></p>
<ul type="disc">
<li><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;"><span lang="EN-US" xml:lang="EN-US" class="hcp16">N</span><span class="hcp16">ame</span> - The name of the stream.
This is used within London Architect only.</p></li>
<li><p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;"><span class="hcp16">ID
Type</span> - Full or Harman. &#160;A stream is given a system
wide unique ID. There are 2 types of ID :-</p></li>
<ul type="disc">
<li><p class="MsoNormal" style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; mso-ansi-language: EN-GB;
font-family: Arial, sans-serif; font-size: 10pt;"><span class="hcp16">Full</span> - The full 8 byte
AVB stream ID. This is usually displayed in hexadecimal
and is used to connect up to non-Harman AVB equipment.</p></li>
<li><p class="MsoNormal" style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; mso-ansi-language: EN-GB;
font-family: Arial, sans-serif; font-size: 10pt;"><span class="hcp16">Harman</span> - A simpler,
smaller stream ID which is used instead of the full stream
ID within a Soundweb London system. This number is simply
shorthand for a range of full 8-byte IDs reserved by Harman.</p></li>
<li><p class="MsoNormal" style="mso-ansi-language: EN-GB;
mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
font-family: Arial, sans-serif; font-size: 10pt;"><span class="hcp16">ID </span>- If the ID Type
is <20>Full<6C> then the ID is a 16 digit Hexadecimal number.
E.g.000FD4001E710000. If you are interfacing to non-London
AVB equipment you should find the stream ID from the 3<sup>rd</sup>
party user interface or software interface.</p></li>
<li><p class="MsoNormal" style="mso-ansi-language: EN-GB;
margin-left: 0px; text-indent: -36px; mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; font-family: Arial, sans-serif;
font-size: 10pt;"><span class="hcp16">Description</span>
- A longer description of the stream for documenting the
design. This is used within London Architect only.</p></li>
<li><p class="MsoNormal" style="margin-left: 0px; text-indent: -36px;
mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;"><span class="hcp16">Number
of Channels</span> - The number of channels in the stream.
Changing this number will add/remove channels from the
stream</p></li>
<li><p class="MsoNormal" style="mso-ansi-language: EN-GB;
margin-left: 0px; text-indent: -36px; mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; font-family: Arial, sans-serif;
font-size: 10pt;"><span style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB;
font-family: Arial, sans-serif;
font-size: 10pt; font-weight: bold;">Channel
List</span><span style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;"> :- The list of
channels within a stream. Channels can be added, deleted,
moved using the buttons on the right. To edit the name
of the strea</span><span style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB;
font-family: Arial, sans-serif;
font-size: 10pt; text-indent: -36px;">m
click on the channel name.</span></p></li>
</ul>
</ul>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;">Channel names are displayed on the Stream
Tx and Rx objects after the signal name.</p>
<h3><b class="hcp11">Stream Restrictions</b></h3>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;">Streams are subject to the following restrictions
:-</p>
<ul style="font-family: Arial, sans-serif; font-size: 10pt;" type="disc">
<li class="hcp12"><p class="MsoNormal" style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; mso-ansi-language: EN-GB;
font-family: Arial, sans-serif;
font-size: 10pt;">An AVB card
cannot receive a stream that it is transmitting. (See example
A)</p></li>
<li class="hcp12"><p class="MsoNormal" style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; mso-ansi-language: EN-GB;
font-family: Arial, sans-serif;
font-size: 10pt;">An AVB card
cannot receive the same stream more than once. (See example
B)</p></li>
<li class="hcp12"><p class="MsoNormal" style="mso-margin-top-alt: auto;
mso-margin-bottom-alt: auto; mso-ansi-language: EN-GB;
font-family: Arial, sans-serif;
font-size: 10pt;">An AVB stream
ID must be unique within an AVB network. (See example C)</p></li>
</ul>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt;">If London Architect detects a problem with
a stream the AVB Input and AVB Output objects are drawn in red.
In this state a tooltip will show what the error is:-</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt; font-weight: bold;">Example A:</p>
<p class="hcp20"><img src="stream&#32;error&#32;-&#32;loopback.jpg" alt="" border="0" class="hcp5"></p>
<p class="hcp21">Example B:</p>
<p class="hcp20"><img src="stream&#32;error&#32;-&#32;talker&#32;conflict.jpg" alt="" border="0" class="hcp5"></p>
<p class="hcp21">Example C:</p>
<p class="hcp20"><img src="stream&#32;error&#32;-&#32;multiple&#32;identical&#32;receives.jpg" alt="" border="0" class="hcp5"></p>
<h2 class="MsoNormal">Control Panel</h2>
<p><img src="AVB&#32;Files/805_DefaultPanel.PNG" alt="" border="0" class="hcp5"></p>
<h3>PTP (Precision Time Protocol)</h3>
<ul type="disc">
<li><h4><span class="hcp10">PTP Grand master
- </span><span lang="EN-US" xml:lang="EN-US" class="hcp22">This
indicator will be amber when the device has arbitrated as
the PTP clock grand master for the cloud.</span></h4></li>
<li><h4 class="MsoNormal"><span class="hcp10">PTP
Locked - </span><span lang="EN-US" xml:lang="EN-US" style="mso-bidi-font-family: 'Times New Roman';
font-weight: normal;">This indicator
will be green when</span><span lang="EN-US" xml:lang="EN-US" class="hcp22"> the
device is grand master for the cloud or if the device has
synchronized with the grand master clock.</span></h4></li>
<li><h4 class="MsoNormal"><span class="hcp10">PTP
Grand Master ID - </span><span lang="EN-US" xml:lang="EN-US" class="hcp22">This
is the ID of the PTP clock that has arbitrated as grand master
for the cloud.</span></h4></li>
<li><h4 class="MsoNormal"><span class="hcp10">PTP
Priority 1 - </span><span lang="EN-US" xml:lang="EN-US" class="hcp22">This value
controls the most significant value of the BMCA (Best Master
Clock Arbitration) priority vector that is used in arbitration
of the clock grand master. &#160;</span><span lang="EN-US" xml:lang="EN-US" class="hcp23">Set
the priority of the PTP Grand Master here. &#160;The device
with the highest priority will be Grand Master. &#160;A priority
setting of 0 is the highest priority and a setting of 255
has the lowest priority.</span></h4></li>
</ul>
<ul type="disc">
<li><h4><span class="hcp10">PTP Priority
2 - </span><span lang="EN-US" xml:lang="EN-US" class="hcp22">This value controls
the least significant value of the BMCA priority vector.</span></h4></li>
</ul>
<ul type="disc">
<li><h4 class="MsoNormal"><span style="mso-bidi-font-family: 'Times New Roman';
mso-ansi-language: EN-GB;">AVB
Peer Primary - </span><span lang="EN-US" xml:lang="EN-US" class="hcp22">This indicator
will be green when the device has recognized that it (the
primary port) is a member of the AVB cloud.</span></h4></li>
<li><p class="MsoNormal" style="mso-ascii-font-family: Calibri;
mso-fareast-font-family: Calibri; mso-hansi-font-family: Calibri;
mso-bidi-font-family: 'Times New Roman';"><span lang="EN-US" xml:lang="EN-US" class="hcp16">AVB Peer Secondary</span><span
lang="EN-US" xml:lang="EN-US"> - This indicator will be green
when the device has recognized that it (the Secondary port)
is a member of the AVB cloud.</span></p></li>
</ul>
<h3>Media Clock</h3>
<ul type="disc">
<li><h4 class="hcp24">Media Clock Master
- <span lang="EN-US" xml:lang="EN-US" class="hcp22">This
indicator is amber when the device is the Media Clock Master
for this media clock domain.</span></h4></li>
<li><h4 class="hcp24">Media Clock ID -
<span lang="EN-US" xml:lang="EN-US" class="hcp22">This
identifier is used by London Architect to ensure that signals
routed from one device to another are synchronized to the
same media clock.</span></h4></li>
<li><h4><span class="hcp10">Media Clock
Locked - </span><span lang="EN-US" xml:lang="EN-US" class="hcp22">This indicator
is green when the device is listening to the house clock stream
for this domain and the house clock has been successfully
recovered from it.</span></h4></li>
<li><h4><span class="hcp10">Media Clock
Priority - </span><span lang="EN-US" xml:lang="EN-US" class="hcp22">This value is
compared during Media Clock Master Arbitration to determine
which device should be the Media Clock Master.</span><span
lang="EN-US" xml:lang="EN-US" style="mso-ascii-font-family: Calibri;
mso-fareast-font-family: Calibri; mso-hansi-font-family: Calibri;
mso-bidi-font-family: 'Times New Roman'; mso-spacerun: yes;
font-weight: normal;">&#160;</span><span lang="EN-US" xml:lang="EN-US" class="hcp22">&#160;A
lower value corresponds to higher priority clock, so setting
this SV to 0 would make the device win most often and 255
would make the device win least often.</span></h4></li>
<li><h4 class="hcp24">MCN Pilot Stream
ID - <span class="hcp23">The full stream ID
of the current pilot stream.</span></h4></li>
</ul>
<h3>The following parameters can be accessed from the <a href="MAINDesign_tree.htm">Design
Tree</a></h3>
<ul type="disc">
<li><h4 class="hcp24">MCN Primary MAC -
<span class="hcp23">S</span><span class="hcp23">hows
the MAC address of the current MCN clock master.</span></h4></li>
<li><h4 class="hcp24">MCN Reserve MAC -
<span class="hcp23">S</span><span class="hcp23">hows
the MAC address of the reserve MCN clock master.</span></h4></li>
<li><h4><span class="hcp10">PTP Path Delay
Primary - </span><span class="hcp25">D</span><span lang="EN-US" xml:lang="EN-US" class="hcp22">elay
(in nanoseconds) between this device and its immediate peer
on the network.</span></h4></li>
<li><h4><span class="hcp10">PTP Path Delay
Secondary - </span><span class="hcp25">D</span><span lang="EN-US" xml:lang="EN-US" class="hcp22">elay
(in nanoseconds) between this device and its immediate peer
on the network.</span></h4></li>
<li><h4 class="hcp24">VLAN ID - <span class="hcp23">The
ID of the VLAN used by the AVB traffic.</span></h4></li>
<li><h4 class="hcp24">Primary Port MAC
- <span class="hcp23">T</span><span class="hcp23">he
MAC address of the primary Ethernet port of the AVBX card.</span></h4></li>
<li><h4 class="hcp24">Secondary Port MAC
- <span class="hcp23">T</span><span class="hcp23">he
MAC address of the secondary Ethernet port of the AVBX card.</span></h4></li>
</ul>
<h2>Transmitter Object (Talker) Properties</h2>
<ul type="disc">
<li><h4 class="hcp24">Stream ID - <span class="hcp23">The ID of the stream. Either
a full 8 byte stream ID or a shorter Harman ID.</span></h4></li>
<li><h4 class="hcp24">State (Stream Active)
- <span class="hcp23">True when the stream
is being transmitted to at least one listener.</span></h4></li>
<li><h4 class="hcp24">Presentation Offset
- <span style="font-weight: normal; font-size: 10pt; font-family: Arial, sans-serif;">The
latency setting of the talker (in nanoseconds). The default
setting is 2ms (2,000,000ns). When set to 2ms, the stream
is guaranteed to be delivered to the receiving device exactly
2ms after transmission, but only if there are 7 or less network
switch hops in between the transmitter and receiver. This
setting can be reduced, at the expense of fewer allowed switch
hops.</span></h4></li>
</ul>
<h2>Receiver Object (Listener) Properties</h2>
<ul type="disc">
<li><h4 class="hcp24">Stream ID -<span class="hcp23"> The ID of the stream. Either
a full 8 byte stream ID or a shorter Harman ID.</span></h4></li>
<li><h4 class="hcp24">State (Stream Active)
- <span class="hcp23">True when the stream
is being received.</span></h4></li>
<li><h4><span class="hcp10">Force Pilot
Stream - </span><span class="hcp23">When 'on'
the RX stream is used as the AVB pilot stream. The pilot stream
is the stream that the London BLU device recovers the audio
clock from. Therefore, if you are interfacing to a 3rd party
device which does not support MCN, you will need to set the
BLU-805 or BLU-325 to sync its audio clock to the stream coming
from that device. So, to receive an audio stream from an AVB
console, you use the full stream ID and set force pilot stream
to On.</span></h4></li>
</ul>
<h2>Clocking</h2>
<p class="MsoNormal"><span class="hcp10">The
device will clock from the AVB under any of the following conditions</span></p>
<ul type="disc">
<li><p class="MsoListParagraphCxSpFirst" style="mso-list: l2 level1 lfo3;"><span class="hcp10">It is an MCN slave and it
is locked to an MCN pilot stream.</span></p></li>
<li><p class="MsoListParagraphCxSpMiddle" style="mso-list: l2 level1 lfo3;"><span class="hcp10">It is an MCN master and
another device is receiving its MCN pilot stream.</span></p></li>
<li><p class="MsoListParagraphCxSpLast" style="mso-list: l2 level1 lfo3;
mso-ansi-language: EN-GB;">It is clocking off one
of the RX streams using the <20>Force Pilot Stream<61> option.</p></li>
</ul>
<p class="MsoListParagraphCxSpLast" style="mso-list: l2 level1 lfo3;
mso-ansi-language: EN-GB;">See <a href="BLU_link.html#Mastership">BLU
link Mastership</a> for further clocking scenarios where the device
is not clocking from the AVB..</p>
<h2><b class="hcp11">AVB vs CobraNet I/O Comparison</b></h2>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt; color: #000000;">Users already familiar with
CobraNet will perhaps find it useful to compare the two transports<74>
I/O capabilities.</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt; color: #000000;">Whereas CobraNet-capable
BLU devices can simultaneously send and receive up to 32 channels
of CobraNet audio (32x32), AVB-capable BLU devices can simultaneously
send and receive up to 64 channels of AVB audio (64x64).</p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt; color: #000000;">Whereas up to 8 channels
of audio can be packaged into 1 CobraNet <20>bundle,<2C> up to 32 channels
of audio can be packaged into 1 AVB <20>stream.<2E></p>
<p class="MsoNormal" style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto;
mso-ansi-language: EN-GB; font-family: Arial, sans-serif;
font-size: 10pt; color: #000000;">Whereas CobraNet-capable
Soundweb London devices can simultaneously transmit up to 4 CobraNet
bundles and receive up to 4 CobraNet bundles (4x4), AVB-capable
Soundweb London devices can simultaneously transmit up to 64 streams
and receive up to 62 streams (62x64).</p>
<h2>PTP (Precision Time Protocol)</h2>
<p class="MsoNormal" style="mso-ansi-language: EN-GB;">Precision
Time Protocol is used to synchronise time in the AVB cloud. One
device is elected as Grand Master and each device uses PTP to
calculate the exact time. Once the devices have agreed on the
current time they can then create synchronised audio clocks using
Media Clock Negotiation.</p>
<h2>MCN (Media Clock Negotiation)</h2>
<p class="MsoNormal"><span class="hcp10">Media
Clock Negotiation is used to synchronise audio clocks between
devices in a single audio clock domain.</span> <span class="hcp26">AVB
allows multiple media clocks on the network with multiple sample
rates co-existing. Each talker stream must specify which media
clock it is using. There can be 256 different media clocks on
an AVB network.</span></p>
<p class="MsoNormal"><span class="hcp26">Individual
AVB devices will have a number of audio clocks that it uses. Typically,
there is one audio clock used by a device and all the audio within
the device uses that clock.</span></p>
<p class="MsoNormal"><span lang="EN-US" xml:lang="EN-US" style="mso-ascii-font-family: Calibri;
mso-fareast-font-family: Calibri;
mso-hansi-font-family: Calibri; mso-bidi-font-family: 'Times New Roman';">Media
clocks are propagated throughout the AVB network using streams.
These streams may also contain data (audio), but that is not a
requirement. For each media clock domain, primary and secondary
clock masters are negotiated using the MCN protocol. If the MCM
priorities for all devices in a given PTP cloud are the same,
the device with the lowest MAC address wins. The primary and secondary
clock masters create media clock streams which all devices can
listen to. Devices monitor the primary and secondary media clock
streams, and if the primary fails the secondary will be promoted
to primary and a new secondary media clock master will be negotiated
based on the defined priority or lowest MAC address.<span class="hcp18">&#160;</span></span></p>
<h2><b class="hcp11">Suitable Switches</b></h2>
<ul style="margin-top: 0cm;" type="disc">
<li class="MsoNormal" style="mso-list: l0 level1 lfo1; tab-stops: list 36.0pt;
font-family: Arial, sans-serif; font-size: 10pt; color: #000000;"><span
lang="EN-US" xml:lang="EN-US">BSS Audio / NETGEAR GS724T Ethernet
Switch</span></li>
<li class="MsoNormal" style="mso-list: l0 level1 lfo1; tab-stops: list 36.0pt;
font-family: Arial, sans-serif; font-size: 10pt; color: #000000;"><span
lang="EN-US" xml:lang="EN-US">LABX Titanium 411 Ruggedized
AVB Ethernet Bridge Switch</span></li>
</ul>
<p><!-- Saved in parser cache with key bugs:pcache:idhash:2873-0!1!0!0!!en!2 and timestamp 20080311165015 --></p>
</div>
</div>
<p style="margin-bottom: 0;">&#160;</p>
<p>&#160;</p>
</body>
</html>