<div dir="ltr">TAPS sounds like a good formulaic solution<div>v</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Mar 21, 2024 at 3:46 AM Marc Blanchet via SIS-DTN <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><br><div><blockquote type="cite"><div>Le 21 mars 2024 à 17:15, Sipos, Brian J. via SIS-DTN <<a href="mailto:sis-dtn@mailman.ccsds.org" target="_blank">sis-dtn@mailman.ccsds.org</a>> a écrit :</div><br><div><div style="font-family:Helvetica;font-size:14px;font-style:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none"><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">All,<u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">I meant to post this earlier to the mailing list instead of individual people.<u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">Another thought related to kernel vs. userspace implementations of protocols are the pattern described in [3], specifically the design in Figure 3 where a kernel module implements the socket API for a new address family but delegates all behavior to a userspace daemon. This is akin to an AF_BUNDLE implementation delegating actual behavior to a userspace BPA implementation (as others have mentioned).<u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">Finally, there is also an IETF Transport Services (TAPS) </div></div></div></blockquote><div><br></div><div>I said exactly that on this mailing list a while ago. One looking at defining a new Transport API should really look into TAPS. TAPS is a generic API for any transport: tcp, quic, udp, sctp, … It has generic transport semantics and a modern approach (all asynchronous).</div><br><blockquote type="cite"><div><div style="font-family:Helvetica;font-size:14px;font-style:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none"><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">effort to create a socket API [4] that has similar logic and behavior to POSIX sockets but presumably not directly tied to kernel implementation so easier to adapt to new AFs and protocols. It looks preliminary, but could be an interesting avenue for prototyping these ideas without getting into kernel module stuff.</div></div></div></blockquote><div><br></div><div>It is more than preliminary. A well-known implementation is Apple, in production, in iOS and MacOSX: i.e. in your hands. I developed networking apps using it, and it is very modern. See: <a href="https://developer.apple.com/documentation/network" target="_blank">https://developer.apple.com/documentation/network</a> . TAPS is an IETF working group that has almost completed its work. See: <a href="https://datatracker.ietf.org/wg/taps/documents/" target="_blank">https://datatracker.ietf.org/wg/taps/documents/</a> (most documents are in or near IESG queue for publication). </div><div><br></div><div>Regards, Marc.</div><br><blockquote type="cite"><div><div style="font-family:Helvetica;font-size:14px;font-style:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none"><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">[3]<span> </span><a href="https://www.usenix.org/system/files/conference/usenixsecurity18/sec18-o_neill.pdf" style="color:blue;text-decoration:underline" target="_blank">https://www.usenix.org/system/files/conference/usenixsecurity18/sec18-o_neill.pdf</a><u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">[4]<span> </span><a href="https://www.ietf.org/archive/id/draft-dreibholz-taps-neat-socketapi-14.html" style="color:blue;text-decoration:underline" target="_blank">https://www.ietf.org/archive/id/draft-dreibholz-taps-neat-socketapi-14.html</a><u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="border-width:medium medium medium 1.5pt;border-style:none none none solid;border-color:currentcolor currentcolor currentcolor blue;padding:0in 0in 0in 4pt"><div><div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(225,225,225) currentcolor currentcolor;padding:3pt 0in 0in"><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><b>From:</b><span> </span>Sipos, Brian J.<span> </span><br><b>Sent:</b><span> </span>Wednesday, March 20, 2024 1:09 AM<br><b>To:</b><span> </span>'<a href="mailto:sburleig.sb@gmail.com" style="color:blue;text-decoration:underline" target="_blank">sburleig.sb@gmail.com</a>' <<a href="mailto:sburleig.sb@gmail.com" style="color:blue;text-decoration:underline" target="_blank">sburleig.sb@gmail.com</a>>;<span> </span><a href="mailto:Jeremy.Mayer@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Jeremy.Mayer@dlr.de</a>;<span> </span><a href="mailto:Felix.Flentge@esa.int" style="color:blue;text-decoration:underline" target="_blank">Felix.Flentge@esa.int</a>;<span> </span><a href="mailto:vint@google.com" style="color:blue;text-decoration:underline" target="_blank">vint@google.com</a><br><b>Subject:</b><span> </span>RE: [EXT] Re: [Sis-dtn] BP Sockets [was RE: IP networking within DTN-based protocol architectures]<u></u><u></u></div></div></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">All,<u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">I agree that the POSIX socket interface provides all of the needed mechanisms do the job of datagram sending/receiving. One thing that I think is an important aspect of BP agent--application interface is the ability for the application to influence sourced metadata and have visibility into delivered metadata (e.g. in addition to the primary block EIDs, things like the Lifetime value or Hop Count values). Since there is a similar need in IP land there are mechanisms like IP_PKTINFO and “control data” like IP_TOS / IP_RECVTOS or IP_TTL / IP_RECVTTL with recvmsg [1].<u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">All of that is when used with SOCK_DGRAM -type sockets sending/receiving ADUs as the msg data. A separate interface with SOCK_RAW -type sockets could have the entire encoded bundle present as the msg data. Similar to using (AF_INET, SOCK_RAW) sockets this allows full visibility into header contents but puts a quite large burden on the application to properly handle and process that data.<u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">On the other hand, implementations of recent transports like QUIC have specifically opted out of in-kernel processing with an associated POSIX socket API. Just something to consider from another recent transport protocol development. Putting implementation into kernel space is quite a large hurdle to clear. But also nothing says you cannot implement a ‘prototype’ userspace API modeled after the sockets API like `bp_socket()` `bp_sendmsg()`, etc.<u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">[1]<span> </span><a href="https://man7.org/linux/man-pages/man7/ip.7.html" style="color:blue;text-decoration:underline" target="_blank">https://man7.org/linux/man-pages/man7/ip.7.html</a><u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif">[2]<span> </span><a href="https://stackoverflow.com/questions/16165542/is-it-possible-to-read-the-ttl-ip-header-field-when-receiving-udp-packets" style="color:blue;text-decoration:underline" target="_blank">https://stackoverflow.com/questions/16165542/is-it-possible-to-read-the-ttl-ip-header-field-when-receiving-udp-packets</a><u></u><u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="border-width:medium medium medium 1.5pt;border-style:none none none solid;border-color:currentcolor currentcolor currentcolor blue;padding:0in 0in 0in 4pt"><div><div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(225,225,225) currentcolor currentcolor;padding:3pt 0in 0in"><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><b>From:</b><span> </span>SIS-DTN <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn-bounces@mailman.ccsds.org</a>><span> </span><b>On Behalf Of<span> </span></b>sburleig.sb--- via SIS-DTN<br><b>Sent:</b><span> </span>Monday, March 11, 2024 10:22 AM<br><b>To:</b><span> </span><a href="mailto:Jeremy.Mayer@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Jeremy.Mayer@dlr.de</a>;<span> </span><a href="mailto:Felix.Flentge@esa.int" style="color:blue;text-decoration:underline" target="_blank">Felix.Flentge@esa.int</a>;<span> </span><a href="mailto:vint@google.com" style="color:blue;text-decoration:underline" target="_blank">vint@google.com</a><br><b>Cc:</b><span> </span><a href="mailto:sis-dtn@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn@mailman.ccsds.org</a><br><b>Subject:</b><span> </span>[EXT] Re: [Sis-dtn] BP Sockets [was RE: IP networking within DTN-based protocol architectures]<u></u><u></u></div></div></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div><div id="m_8865371980788089320APLWarningText"><table border="0" cellspacing="0" cellpadding="0" align="left"><tbody><tr><td width="100%" style="width:569.344px;background:rgb(224,224,224);padding:0in"><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><b><span style="color:red">APL external email warning:<span> </span></span></b><span>Verify sender<span> </span><a href="mailto:sis-dtn-bounces@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn-bounces@mailman.ccsds.org</a>before clicking links or attachments</span><u></u><u></u></div></td></tr></tbody></table><p> <u></u><u></u></p></div></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos">Right, the service interface in the CCSDS BP specification -- like all service specifications -- is abstract; it defines the properties of a BP API for the purpose of explaining the required behavior of a Bundle Protocol Agent. Any number of existing and future BP implementations with very different APIs can be wholly conformant to that specification. But a BP sockets specification would enable any application that currently communicates over POSIX (BSD) sockets to use BP instead of UDP without extensive code changes; the syntax is already in place. That’s the compelling advantage of the idea.<u></u><u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos"><u></u> <u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos">Scott<u></u><u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos"><u></u> <u></u></span></div><div><div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(225,225,225) currentcolor currentcolor;padding:3pt 0in 0in"><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><b>From:</b><span> </span><a href="mailto:Jeremy.Mayer@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Jeremy.Mayer@dlr.de</a><span> </span><<a href="mailto:Jeremy.Mayer@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Jeremy.Mayer@dlr.de</a>><span> </span><br><b>Sent:</b><span> </span>Monday, March 11, 2024 3:48 AM<br><b>To:</b><span> </span><a href="mailto:Felix.Flentge@esa.int" style="color:blue;text-decoration:underline" target="_blank">Felix.Flentge@esa.int</a>;<span> </span><a href="mailto:sburleig.sb@gmail.com" style="color:blue;text-decoration:underline" target="_blank">sburleig.sb@gmail.com</a>;<span> </span><a href="mailto:vint@google.com" style="color:blue;text-decoration:underline" target="_blank">vint@google.com</a><br><b>Cc:</b><span> </span><a href="mailto:sis-dtn@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn@mailman.ccsds.org</a><br><b>Subject:</b><span> </span>RE: BP Sockets [was RE: [Sis-dtn] IP networking within DTN-based protocol architectures]<u></u><u></u></div></div></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Hi,<u></u><u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">In the abstract, I’d say so, but (let’s be honest) many developers tend to ignore the abstract notion of the service interface and prefer to have a tangible set of API operations.<u></u><u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"><u></u> <u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Thanks,<u></u><u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Jeremy<u></u><u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"><u></u> <u></u></span></div><div><div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(225,225,225) currentcolor currentcolor;padding:3pt 0in 0in"><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><b>From:</b><span> </span>Felix Flentge <<a href="mailto:Felix.Flentge@esa.int" style="color:blue;text-decoration:underline" target="_blank">Felix.Flentge@esa.int</a>><span> </span><br><b>Sent:</b><span> </span>Montag, 11. März 2024 11:46<br><b>To:</b><span> </span><a href="mailto:sburleig.sb@gmail.com" style="color:blue;text-decoration:underline" target="_blank">sburleig.sb@gmail.com</a>; Mayer, Jeremy <<a href="mailto:Jeremy.Mayer@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Jeremy.Mayer@dlr.de</a>>;<span> </span><a href="mailto:vint@google.com" style="color:blue;text-decoration:underline" target="_blank">vint@google.com</a><br><b>Cc:</b><span> </span><a href="mailto:sis-dtn@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn@mailman.ccsds.org</a><br><b>Subject:</b><span> </span>BP Sockets [was RE: [Sis-dtn] IP networking within DTN-based protocol architectures]<u></u><u></u></div></div></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE"><u></u> <u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Hi,<u></u><u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"><u></u> <u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">I like the idea but isn’t this already covered (partially) by the CCSSDS BP service interface, eg:<u></u><u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"><u></u> <u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="DE">Bind – register EID in passive state<u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Listen –<span> </span></span><span lang="DE">register EID in active state</span><span lang="EN-GB"><u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Connect – sets a default destination for future send.request<u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Send – send.request<span> </span><u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Recv – poll.request<u></u><u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"><u></u> <u></u></span></div><div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Regards,<u></u><u></u></span></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Felix<u></u><u></u></span></div></div><div style="margin:0in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"><u></u> <u></u></span></div><div><div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(225,225,225) currentcolor currentcolor;padding:3pt 0in 0in"><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><b>From:</b><span> </span>SIS-DTN <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn-bounces@mailman.ccsds.org</a>><span> </span><b>On Behalf Of<span> </span></b>sburleig.sb--- via SIS-DTN<br><b>Sent:</b><span> </span>Saturday, March 9, 2024 6:56 PM<br><b>To:</b><span> </span><a href="mailto:Jeremy.Mayer@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Jeremy.Mayer@dlr.de</a>;<span> </span><a href="mailto:vint@google.com" style="color:blue;text-decoration:underline" target="_blank">vint@google.com</a><br><b>Cc:</b><span> </span><a href="mailto:sis-dtn@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn@mailman.ccsds.org</a><br><b>Subject:</b><span> </span>Re: [Sis-dtn] IP networking within DTN-based protocol architectures<u></u><u></u></div></div></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"><u></u> <u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos">Thanks for that analysis, Jeremy. We’ve been talking about at least since STINT several years ago, and I really think it’s an idea whose time has come.<u></u><u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos"><u></u> <u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos">Scott<u></u><u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos"><u></u> <u></u></span></div><div><div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(225,225,225) currentcolor currentcolor;padding:3pt 0in 0in"><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><b>From:</b><span> </span><a href="mailto:Jeremy.Mayer@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Jeremy.Mayer@dlr.de</a><span> </span><<a href="mailto:Jeremy.Mayer@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Jeremy.Mayer@dlr.de</a>><span> </span><br><b>Sent:</b><span> </span>Saturday, March 9, 2024 8:01 AM<br><b>To:</b><span> </span><a href="mailto:vint@google.com" style="color:blue;text-decoration:underline" target="_blank">vint@google.com</a>;<span> </span><a href="mailto:sburleig.sb@gmail.com" style="color:blue;text-decoration:underline" target="_blank">sburleig.sb@gmail.com</a><br><b>Cc:</b><span> </span><a href="mailto:Tomaso.deCola@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Tomaso.deCola@dlr.de</a>;<span> </span><a href="mailto:sis-dtn@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn@mailman.ccsds.org</a><br><b>Subject:</b><span> </span>RE: [Sis-dtn] IP networking within DTN-based protocol architectures<u></u><u></u></div></div></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><u></u> <u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Hi,<u></u><u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">That’s a fair point. Generally, I’d say that BP-POSIX could work with the following:<u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Bind – works: sets source EID.<u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Listen – works; sets source EID and opens reception.<span> </span><u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Connect – UDP style, sets default destination address.<u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Send – only valid for connected bundlesocks.<span> </span><u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Sendto/sendmsg – works.<u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Recv – works.<u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Recvfrom/recvmsg – works, probably should support “wildcard” EIDs, at least for services.<span> </span><u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Getaddrinfo and friends – not required<u></u><u></u></span></div><div style="margin:0in 0in 0in 1in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB" style="font-family:Symbol"><span>·<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span></span><span lang="EN-GB">Select – Works, highly implementation dependent.<u></u><u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"><u></u> <u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">BSD sockets really do work for everything!<u></u><u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"><u></u> <u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Thanks,<u></u><u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Jeremy<u></u><u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"><u></u> <u></u></span></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"><u></u> <u></u></span></div><div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(225,225,225) currentcolor currentcolor;padding:3pt 0in 0in"><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><b>From:</b><span> </span>Vint Cerf <<a href="mailto:vint@google.com" style="color:blue;text-decoration:underline" target="_blank">vint@google.com</a>><span> </span><br><b>Sent:</b><span> </span>Samstag, 9. März 2024 16:51<br><b>To:</b><span> </span>Scott Burleigh <<a href="mailto:sburleig.sb@gmail.com" style="color:blue;text-decoration:underline" target="_blank">sburleig.sb@gmail.com</a>><br><b>Cc:</b><span> </span>Mayer, Jeremy <<a href="mailto:Jeremy.Mayer@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Jeremy.Mayer@dlr.de</a>>; de Cola, Tomaso <<a href="mailto:Tomaso.deCola@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Tomaso.deCola@dlr.de</a>>; Dr. Keith L Scott via SIS-DTN <<a href="mailto:sis-dtn@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn@mailman.ccsds.org</a>><br><b>Subject:</b><span> </span>Re: [Sis-dtn] IP networking within DTN-based protocol architectures<u></u><u></u></div></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE"><u></u> <u></u></span></div><div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE">Yes generally speaking<u></u><u></u></span></div></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE"><u></u> <u></u></span></div><div><div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE">On Sat, Mar 9, 2024, 10:43 <</span><a href="mailto:sburleig.sb@gmail.com" style="color:blue;text-decoration:underline" target="_blank"><span lang="DE">sburleig.sb@gmail.com</span></a><span lang="DE">> wrote:<u></u><u></u></span></div></div><blockquote style="border-width:medium medium medium 1pt;border-style:none none none solid;border-color:currentcolor currentcolor currentcolor rgb(204,204,204);padding:0in 0in 0in 6pt;margin:5pt 0in 5pt 4.8pt"><div><div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos">I think we get closer to BSD/POSIX if we use UDP as a model. The attenuated UDP notion of connect() would work for BP, I think.</span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos"> </span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos">Scott</span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span style="font-family:Aptos"> </span><u></u><u></u></div><div><div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(225,225,225) currentcolor currentcolor;padding:3pt 0in 0in"><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><b>From:</b><span> </span>SIS-DTN <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn-bounces@mailman.ccsds.org</a>><span> </span><b>On Behalf Of<span> </span></b>Jeremy Mayer via SIS-DTN<br><b>Sent:</b><span> </span>Saturday, March 9, 2024 12:35 AM<br><b>To:</b><span> </span><a href="mailto:vint@google.com" style="color:blue;text-decoration:underline" target="_blank">vint@google.com</a>;<span> </span><a href="mailto:Tomaso.deCola@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Tomaso.deCola@dlr.de</a><br><b>Cc:</b><span> </span><a href="mailto:sis-dtn@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn@mailman.ccsds.org</a><br><b>Subject:</b><span> </span>Re: [Sis-dtn] IP networking within DTN-based protocol architectures<u></u><u></u></div></div></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"> <u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Hi,</span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">I’m tempted to agree. I’ve seen limited utility in IP->BP encap, as (other than some unidirectional UDP-based applications), the assumptions made in IP networks (especially TCP) do not scale well to DTN environments. The two largest issues I see are:</span><u></u><u></u></div><p style="margin-right:0in;margin-left:1in;font-size:11pt;font-family:Calibri,sans-serif"><span>A.<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span><span lang="EN-GB">The assumption that relatively low-latency and bidirectional communication is available.</span><u></u><u></u></p><p style="margin-right:0in;margin-left:1in;font-size:11pt;font-family:Calibri,sans-serif"><span>B.<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span><span lang="EN-GB">The layering of stream and message-based semantics.</span><u></u><u></u></p><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"> </span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Almost every TCP-ish application which I’ve seen run over BP winds up with exceptionally low performance, unless some sort of PEP is integrated, which adds complexity, failure points, and fragility.<span> </span></span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"> </span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">+1 for the notion of a standard API though, with the additional caveat that we should standardize nomenclature across implementations. We could likely reuse about 80% of the BSD/POSIX interface for BP, with the notable exception of connect.</span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"> </span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Thanks,</span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB">Jeremy</span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="EN-GB"> </span><u></u><u></u></div><div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(225,225,225) currentcolor currentcolor;padding:3pt 0in 0in"><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><b>From:</b><span> </span>SIS-DTN <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn-bounces@mailman.ccsds.org</a>><span> </span><b>On Behalf Of<span> </span></b>Vint Cerf via SIS-DTN<br><b>Sent:</b><span> </span>Freitag, 8. März 2024 12:31<br><b>To:</b><span> </span>de Cola, Tomaso <<a href="mailto:Tomaso.deCola@dlr.de" style="color:blue;text-decoration:underline" target="_blank">Tomaso.deCola@dlr.de</a>><br><b>Cc:</b><span> </span><a href="mailto:sis-dtn@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank">sis-dtn@mailman.ccsds.org</a><br><b>Subject:</b><span> </span>Re: [Sis-dtn] IP networking within DTN-based protocol architectures<u></u><u></u></div></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE"> </span><u></u><u></u></div><div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE">The more I think about this, the less I like trying to manage off-Earth IP networks remotely. I think I would much rather see native applications running over BP. In any case we need to develop standard APIs for BP, such as the Sockets interface for Linux/Unix/Posix. </span><u></u><u></u></div><div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE"> </span><u></u><u></u></div></div><div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE">We do need to figure out how IP-based and BP-based applications interwork. What do Domain Names mean in the BP context for example. </span><u></u><u></u></div></div><div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE"> </span><u></u><u></u></div></div><div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE">v</span><u></u><u></u></div></div><div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE"> </span><u></u><u></u></div></div></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE"> </span><u></u><u></u></div><div><div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE">On Fri, Mar 8, 2024 at 4:24 AM Tomaso de Cola via SIS-DTN <</span><a href="mailto:sis-dtn@mailman.ccsds.org" style="color:blue;text-decoration:underline" target="_blank"><span lang="DE">sis-dtn@mailman.ccsds.org</span></a><span lang="DE">> wrote:</span><u></u><u></u></div></div><blockquote style="border-width:medium medium medium 1pt;border-style:none none none solid;border-color:currentcolor currentcolor currentcolor rgb(204,204,204);padding:0in 0in 0in 6pt;margin:5pt 0in 5pt 4.8pt"><div><div><div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE">Dear All,</span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE"> </span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif">as mentioned yesterday during our DTN weekly, during the past Fall meeting a presentation was given by University of Nanjing with the support of Chinese agency about IP-networking within DTN-based protocol stacks, especially for planetary network segments (i.e. what is often referred to as IP-islands).<span> </span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif">The link to that presentation is as follows:<u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"> <u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><a href="https://cwe.ccsds.org/sis/docs/SIS-DTN/Meeting%20Materials/2023/Fall%202023%20SIS-DTN/Possible%20BOF%20Discussion.pptx?d=w44d31f0b3be649e4bf24ec4ae50479a1" style="color:blue;text-decoration:underline" target="_blank">https://cwe.ccsds.org/sis/docs/SIS-DTN/Meeting%20Materials/2023/Fall%202023%20SIS-DTN/Possible%20BOF%20Discussion.pptx?d=w44d31f0b3be649e4bf24ec4ae50479a1</a><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"> <u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif">The proposal made there was for a BOF (i.e. towards a WG formation), which I see however too premature. On the contrary, I’d be more in favour for a SIG (Special Interest Group), happening outside the DTN WG.<u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"> <u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif">As discussed yesterday, key points to clarify/agree are:<u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"> <u></u><u></u></div><p style="margin-right:0in;margin-left:1in;font-size:11pt;font-family:Calibri,sans-serif"><span>1.<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span>Is the proposal sound and meaningful to be addressed?<u></u><u></u></p><p style="margin-right:0in;margin-left:1in;font-size:11pt;font-family:Calibri,sans-serif"><span>2.<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span>Is appropriate for the SIS area or should be better addressed at architectural level in SEA (maybe it can be even a cross-area initiative)?<u></u><u></u></p><p style="margin-right:0in;margin-left:1in;font-size:11pt;font-family:Calibri,sans-serif"><span>3.<span style="font-style:normal;font-variant-caps:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman";font-kerning:auto;font-variant-alternates:normal;font-variant-ligatures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;font-feature-settings:normal"> <span> </span></span></span>In the case of SIS, is there significant support to start this? In other words, which agencies have interest in contributing to this activity?<u></u><u></u></p><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"> <u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif">Thank you for sharing comments/objections/suggestions.<u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"> <u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif">Have a nice weekend,<u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"> <u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif">Tomaso<u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"> <u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><span lang="DE" style="font-size:10pt;font-family:Arial,sans-serif;color:dimgray">————————————————————————</span><span lang="DE" style="font-size:12pt;font-family:"Times New Roman",serif"></span><u></u><u></u></div><div style="margin:0in 0in 0in 0.5in;font-size:11pt;font-family:Calibri,sans-serif"><b><span lang="DE" style="font-size:10pt;font-family:Arial,sans-serif;color:dimgray">Deutsches Zentrum für Luft- und Raumfahrt</span></b><span lang="DE" style="font-size:10pt;font-family:Arial,sans-serif;color:dimgray"><span> </span>(DLR)</span><span lang="DE" style="font-size:12pt;font-family:"Times New Roman",serif;color:rgb(31,73,125)"><br></span><span lang="DE" style="font-size:10pt;font-family:Arial,sans-serif;color:dimgray">German Aerospace Center</span><span lang="DE" style="font-size:12pt;font-family:"Times New Roman",serif;color:rgb(31,73,125)"><br></span><span lang="DE" style="font-size:10pt;font-family:Arial,sans-serif;color:dimgray">Institute of Communications and Navigation | Satellite 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