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<DIV dir=ltr align=left><SPAN class=384422613-21042009><FONT face=Arial
color=#0000ff size=2>William,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=384422613-21042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=384422613-21042009><FONT face=Arial
color=#0000ff size=2>This note means that you need to be able to receive encap
packets with any of the various header sizes, in the general case. If a
program knows that they would never be receiving data from anybody using the 8
byte header, they would not have to be able to support it. A program can
also choose never to transmit 8 byte headers.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=384422613-21042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=384422613-21042009><FONT face=Arial
color=#0000ff size=2>Dave</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=384422613-21042009></SPAN> </DIV><BR>
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<FONT face=Tahoma size=2><B>From:</B> sis-ipo-bounces@mailman.ccsds.org
[mailto:sis-ipo-bounces@mailman.ccsds.org] <B>On Behalf Of </B>Walsh,
William<BR><B>Sent:</B> Tuesday, April 21, 2009 12:22 AM<BR><B>To:</B>
'Greenberg, Edward'; 'Kazz, Greg J'; sls-slp@mailman.ccsds.org;
sis-ipo@mailman.ccsds.org<BR><B>Subject:</B> RE: [Sis-ipo] Adding a note to
Encapsulation Service 4.2.2.4<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Greg,
Dave,<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Did this discussion
refer to the 2, 4 vs 8 byte encap headers,<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">with 1, 2 or 4 byte
length fields?<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Note that most programs
that I’ve talked to explicitly exempt their<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">contractors from
supporting the 8 byte encap header.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">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 face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">variable – I’m not sure
that part is a bandwidth issue.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">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 face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Regards,<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">william<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
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<P class=MsoNormal><B><FONT face=Tahoma size=2><SPAN
style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">From:</SPAN></FONT></B><FONT
face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; 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></DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-BOTTOM: 12pt"><FONT face=Verdana size=1><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: 12pt"><FONT face=Arial size=1><SPAN
style="FONT-SIZE: 6pt; 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 color=navy size=1><SPAN
style="FONT-SIZE: 6pt; 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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