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<title>Re: [Sis-ipo] Adding a note to Encapsulation Service 4.2.2.4</title>
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Greg, Dave,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Did this discussion refer to the 2, 4 vs 8
byte encap headers,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>with 1, 2 or 4 byte length fields?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Note that most programs that I’ve
talked to explicitly exempt their<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>contractors from supporting the 8 byte
encap header.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>If this comment regards the choices of
idle packets, i.e. 1-byte vs.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>variable – I’m not sure that
part is a bandwidth issue.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I apologize that I don’t clearly
remember the context of the discussion today.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Regards,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>william<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
sis-ipo-bounces@mailman.ccsds.org [mailto:sis-ipo-bounces@mailman.ccsds.org] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Greenberg, Edward<br>
<b><span style='font-weight:bold'>Sent:</span></b> Monday, April 20, 2009 9:17
PM<br>
<b><span style='font-weight:bold'>To:</span></b> Kazz, Greg J;
sls-slp@mailman.ccsds.org; sis-ipo@mailman.ccsds.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Sis-ipo] Adding a
note to Encapsulation Service 4.2.2.4</span></font><o:p></o:p></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'><font size=1 face=Verdana><span
style='font-size:4.5pt;font-family:Verdana'>I agree with Dave’s comment
except it should be a normative statement not a NOTE!<br>
<br>
<br>
On 4/20/09 9:12 PM, "Kazz, Greg J" <greg.j.kazz@jpl.nasa.gov>
wrote:</span></font><o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=1 face=Arial><span
style='font-size:6.0pt;font-family:Arial'>All,<br>
<br>
During today’s SIS-IPO meeting, Dave Israel made what I believe is a very
good suggestion, discovered during interoperability testing IP/IPE over
Encapsulation over AOS frames.<br>
<br>
The problem with the current wording of the Encapsulation Service Specification
is that two independent implementations will not interoperate if the receive
side of the interface implements Encapsulation packet size differently with
respect to the transmit side.<br>
<br>
The proposed note would be added to the Encapsulation Service Pink Sheets,
which is a topic for discussion in the SLS-SLP WG meeting on Friday. The
section is 4.2.2.4 Length of Length Field<br>
<br>
The proposed note is:<br>
<br>
</span></font><font size=1 color=navy><span style='font-size:6.0pt;color:navy'>NOTE
- An implementation <b><span style='font-weight:bold'>on the
transmitting end</span></b> may choose to either use a fixed Encapsulation
header size or adaptively/dynamically adjust the size of the Encapsulation
Header size according to the payload size in order to optimize bandwidth use
(minimize header overhead). Therefore, an implementation must be capable
of receiving encapsulation packets implementing either case. <br>
<br>
Greg<br>
<br>
</span></font><o:p></o:p></p>
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