[Sois-tcons] RE: Updated version of TCONS Red book on CWE

[Scott,Keith L.]

Steve,

Sounds great.  So really in Figure 2-2, there is a (not shown) 'TCONS
Transport' in addition to the TCP/UDP examples.  That is, the blue box
could read 'Transport (e.g. TCONS-TP, TCP, UDP).  Presumably same for
network.  Sounds great.  Also, if other transport protocols are adopted
and/or developed for on-board systems, fine by me (and the interfaces
in 2-2 should support them cleanly).

My apologies about being confused and mentioning a sockets interface;
you are correct in that the API to the applications (TCOA or other) is
something different from the Inter Network Service interface in the
figure.

As for referencing SCPS-TP, TCP, and UDP, I believe that CCSDS 714.0b1
(SCPS-TP) does this.  It simply adopts UDP, and admits the possibility
of using 'plain' TCP and/or the SCPS-TP extensions.

I plan to be in Atlanta all week, mostly for Cislunar stuff but I also
think there's an interaction between Cislunar and TCONS.  I can speak
for SIS to some degree; if I'm not enough then we can hunt up Dai.

		--keith

>-----Original Message-----
>From: Steve Parkes [mailto:sparkes at computing.dundee.ac.uk] 
>Sent: Monday, August 29, 2005 11:58 AM
>To: Scott,Keith L.; Jane K. Marquart; 
>sois-tcons at mailman.ccsds.org; Peter.Shames at jpl.nasa.gov; 
>dstanton at keltik.co.uk
>Cc: 'Massimiliano.Ciccone at esa.int'
>Subject: RE: [Sois-tcons] RE: Updated version of TCONS Red book on CWE
>
>Keith,
>
>The consensus in Athens was that "Time Critical" only makes 
>sense over a
>single sub-network and also that we wanted to support the SIS 
>view of the
>world (or maybe universe) and support TCP/IP etc. We did not 
>believe that
>TCP/IP would be able to provide appropriate time critical 
>behaviour. The
>focus thus was on sorting out an appropriate architecture, formulating
>suitable QoS mechanisms and then providing the service 
>interfaces. We are
>about half way through this at the moment and are currently 
>trying to sort
>out a consistent QoS approach that can be applied to (almost) 
>any underlying
>bus/sub-network. 
>
>For onboard applications we also thought that TCP/IP etc may not be
the
>final word and that we should provide mechanisms for handling other
>protocols as well. This includes using the Intra-Network layer 
>directly from
>TCOAS and other applications.
>
>The socket API approach was considered as the TCONS interface and is
>certainly very attractive if only TCP/IP etc is being used. 
>With support for
>other protocols being considered too the socket API was not 
>possible and Max
>Ciccone is currently working on a draft red book for the Inter-Network
>Service Interface.
>
>I think that the rest of your interpretation is correct.
>
>We are happy for SIS to take on the TCP/IP side of the 
>standard definition.
>In fact what we would like to do is to simply call up an existing
CCSDS
>standard. This would then be a box within TCONS rather than the full
>transport and network layer, because we want to be able to handle
other
>onboard transport and network protocols.
>
>As I have said our current focus is on the architecture and 
>QoS approach.
>The primary aim of our meetings in Atlanta is to get this 
>finalised and out
>for review. We would also like to discuss the architecture 
>(and QoS) with
>SIS so that our views of the universe can converge, and also 
>to make a start
>on some of the other red books that we have on our list. Can 
>we arrange a
>meeting with SIS to discuss the architecture?
>
>Regards
>
>Steve
>
>------------------------------------------
>Steve Parkes
>Space Technology Centre
>Applied Computing, University of Dundee
>Dundee, DD1 4HN, Scotland, UK
>Tel: +44 1382 345194
>Fax: +44 1382 348838
>Mobile: +44 784 138 3779
> 
>
>-----Original Message-----
>From: sois-tcons-bounces at mailman.ccsds.org
>[mailto:sois-tcons-bounces at mailman.ccsds.org] On Behalf Of 
>Scott,Keith L.
>Sent: 29 August 2005 16:35
>To: Jane K. Marquart; sois-tcons at mailman.ccsds.org;
>Peter.Shames at jpl.nasa.gov; dstanton at keltik.co.uk
>Subject: [Sois-tcons] RE: Updated version of TCONS Red book on CWE
>
>Jane,
>
>I have a question about figure 2-2 (TCONS/OBL Architecture).  There
are
>both Intra-Network and Inter-network layers shown, as well as a number
>of different data link layers.  In Athens I thought the consensus was
>that TCONS would provide time-critical services over a single
>subnetwork.  Is this still the intent of the architecture, with TCONS
>using TCP/UDP/IP to provide time-critical service, or is the intent to
>attempt to provide time-critcal services over (between) heterogeneous
>data links?
>
>What about the paragraph in section 3.1: "The network layer is
>responsible for routing datagrams across heterogeneous sub-networks,
>from source address to destination address, delivering them to the
>required destination."
>
>If the thought is that TCONS networks will support networking
protocols
>(e.g. NP/IP), and that these networking protocols can be used to get
>'out' of a TCONS (providing time-critical services) subnetwork and
into
>other subnets, I think that fits well with the SIS view of things.
The
>red "Inter Network Service Interface" in Figure 2-2 then is then (or
>maybe could be) a standard sockets interface, with time-critical
>requirements managed by the TCONS API?  Reading it this way, an
>application requiring time-critical services would use the TCONS API;
>the TCONS API block would choose a transport service (TCP/UDP) and
>interact with the QoS function to allocate slots, etc.  I don't think
I
>have any problems with this interpretation.
>
>Using this interpretation, if TCONS is making use of TCP/UDP/IP, one
>_could_ redraw figure 2-2 with the TCONS API as part of TCONS, the red
>line from the TCONS API to the Intra-Network Service Interface as part
>of TCONS, and the transport and network protocols as (IETF/adopted by
>SIS) standards.  TCONS would also 'own' the Intra Network Service
>Interface (which it must control in order to preserve/protect its
>time-critical service), as well as the Intra-Network stuff.
>
>Does this match the current TCONS thinking?
>
>		--keith
>
>
>>-----Original Message-----
>>From: Jane K. Marquart [mailto:Jane.K.Marquart at nasa.gov] 
>>Sent: Monday, August 29, 2005 10:50 AM
>>To: sois-tcons at mailman.ccsds.org; Scott,Keith L.; 
>>Peter.Shames at jpl.nasa.gov; dstanton at keltik.co.uk
>>Subject: Updated version of TCONS Red book on CWE
>>
>>All,
>>
>>I've incorporated MOST comments into Version 2 of the TCONS 
>>Architecture 
>>Redbook and put on the CWE (also attached for convenience).  
>>Please provide 
>>feedback promptly.  There continues to be confusion as to what 
>>and why of 
>>the architecture.  Hopefully, the updates will help to 
>>clarify.  Feedback 
>>from SIS is especially requested so we don't have disconnects 
>>and wind up 
>>dealing with the same issues in Atlanta as we did in Athens.
>>Thanks to all who have responded thus far.  I'll continue to try and 
>>resolve any outstanding comments.
>>
>
>_______________________________________________
>Sois-tcons mailing list
>Sois-tcons at mailman.ccsds.org
>http://mailman.ccsds.org/mailman/listinfo/sois-tcons
>