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[184.162.66.108]) by smtp.gmail.com with ESMTPSA id i6-20020ad44ba6000000b00690079e6a28sm75920qvw.123.2024.02.28.11.28.10 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 28 Feb 2024 11:28:11 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.400.31\)) From: Marc Blanchet In-Reply-To: Date: Wed, 28 Feb 2024 14:28:00 -0500 Cc: Alexandre Petrescu , starlink@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: References: To: Tomaso DeCola X-Mailer: Apple Mail (2.3774.400.31) Subject: Re: [Starlink] space packet protocol document X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 28 Feb 2024 19:28:13 -0000 > Le 28 f=C3=A9vr. 2024 =C3=A0 13:53, Tomaso de Cola via Starlink = a =C3=A9crit : >=20 > But there exists already a CCSDS spec for IP over CCSDS=E2=80=A6 Right, but it is underspecified. It just specifies which value to put in = the frame to identify IP in the payload. It does not talk about how to = actually use IPv6 in such context: neighbor discovery, IP addresses, = DAD, =E2=80=A6 IETF had made IPv6 over Foo RFCs for that specific = matter. Right now, I doubt that two implementations (if any of IPv6 over = CCSDS links exists) would interoperate with this under spec. Marc. > Moreover the snapshot you attached is about TC frames, I.e. for = telecommand services=E2=80=A6 >=20 > Tomaso > Sent from my iPhone >=20 >> On 28. Feb 2024, at 18:47, Alexandre Petrescu via Starlink = wrote: >>=20 >> =EF=BB=BFThe CCSDS spec is an interesting document. >>=20 >> I am trying to find a packet dump of a CCSDS packet that travelled in = space according to this CCSDS spec. If there is a place with CCSDS = packet dumps I am interested to see them. >>=20 >> Given that, I could think about writing an IPv6-over-CCSDS = preliminary Internet Draft. >>=20 >> I could find a png image of a packet dump at ESA = (https://essr.esa.int/project/ccsds-wireshark-dissector), but that is = not a real packet dump binary file that could be loaded in wireshark; = strangely, they do provide a dissector, but not a packet. >>=20 >> Here are my IPv6 comments about CCSDS, relative to that png of a = CCSDS packet (png attached): >>=20 >>> - the shown 'Frame Length' field is on 16bits. For IPv6, this can = be fine, in principle. The good thing is that the minimum MTU of IPv6 is = 1280, and that can be encoded ok with a 16bit length field. On another = hand, the 'Payload Length' of IPv6 is also on 16bit. This means that = the largest normal IPv6 packet would not fit into a single CCSDS frame, = and would need to be fragmented by CCSDS. Maybe fragmentation is little = desirable when RTT is 45minutes. And, there are also the IPv6 = 'jumbograms'. >>>=20 >>> - there is a 'Spacecraft ID' and 'VC ID' fields combined on 16bits: = this field could be used, if appropriate in some context, to help with = forming IPv6 link-local addresses. If there is worry about privacy, and = these IDs could be used to input hashes, such as to obtain hopefully = unique numbers; these hopefully unique numbers are often necessary when = designing IPv6 addressing architectures, subnet numbers, IPv6 ULA = addresses, secure addresses for secure identification, and similar. >>>=20 >>> - there is a 'SDLS Header' containing a 'Security Parameter Index' = field. If this packet contains an IPv6 packet with an ESP header = (encapsulated sec'y protocol) then that too has a 'Security Parameter = Index' field (SPI). It would be good to re-use. Ideally, one would = rely entirely on IPsec and almost not at all on CCSDS-specific security. >>=20 >> Alex >>=20 >>> Le 23/02/2024 =C3=A0 19:03, Dave Taht via Starlink a =C3=A9crit : >>> Given the trouble the moon lander has had communicating, I looked = over >>> this just now. >>>=20 >>> https://public.ccsds.org/Pubs/133x0b2e1.pdf >>>=20 >>> I reviewed a similar document for the earth-moon corridor by NASA >>> about 2 years ago, and it was a mess of non-interoperable bands and >>> protocols. I cannot remember the name of that one. >> >> _______________________________________________ >> Starlink mailing list >> Starlink@lists.bufferbloat.net >> https://lists.bufferbloat.net/listinfo/starlink > _______________________________________________ > Starlink mailing list > Starlink@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/starlink