<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Thanks for the comments Ondrej!<div class=""><br class=""></div><div class="">I agree with the points you raise, and I think we've improved this in RFC6126bis:</div><div class=""><a href="https://tools.ietf.org/html/draft-ietf-babel-rfc6126bis" class="">https://tools.ietf.org/html/draft-ietf-babel-rfc6126bis</a></div><div class=""><br class=""></div><div class="">Could you take a look at the updated document and let us know what you think?</div><div class=""><br class=""></div><div class="">Thanks,</div><div class="">David</div><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Oct 26, 2017, at 07:47, Juliusz Chroboczek <<a href="mailto:jch@irif.fr" class="">jch@irif.fr</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">Forwarded with permission of the author.<br class=""><br class=""><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(127, 127, 127, 1.0);" class=""><b class="">From: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">Ondrej Zajicek <<a href="mailto:santiago@crfreenet.org" class="">santiago@crfreenet.org</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(127, 127, 127, 1.0);" class=""><b class="">Subject: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class=""><b class="">Some notes on seqno requests in Babel</b><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(127, 127, 127, 1.0);" class=""><b class="">Date: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">October 26, 2017 at 05:15:02 PDT<br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(127, 127, 127, 1.0);" class=""><b class="">To: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">Juliusz Chroboczek <<a href="mailto:jch@irif.fr" class="">jch@irif.fr</a>>, Toke Høiland-Jørgensen <<a href="mailto:toke@toke.dk" class="">toke@toke.dk</a>><br class=""></span></div><br class=""><br class="">Hi Juliusz and Toke<br class=""><br class="">I am fixing some issues in Babel code in BIRD related to seqno requests<br class="">and i found that parts of the Babel RFC less than clear.<br class=""><br class="">1) 3.2.6. The Table of Pending Requests<br class=""><br class=""> The table of pending requests contains a list of seqno requests that<br class=""> the local node has sent (either because they have been originated<br class=""> locally, or because they were forwarded) and to which no reply has<br class=""> been received yet. This table is indexed by prefixes, and every<br class=""> entry in this table contains the following data:<br class=""><br class="">The paragraph says that the table is indexed by prefixes. I would assume<br class="">it means that prefix is a unique key for the table, so no two entries<br class="">have the same prefix. That would work for forwarded requests, but IMHO<br class="">there may be multiple pending locally originated requests for the same<br class="">prefix with different router-id resulting from actions by section<br class="">3.8.2.2. Dealing with Unfeasible Updates.<br class=""><br class="">I guess it could be handled by keeping only the request related to the<br class="">route with the best metric, or should we keep multiple pending<br class="">requests with different router-ids?<br class=""><br class="">BIRD currently uses (prefix, router-id, seqno) as a key, where different<br class="">seqno values are clearly not necessary.<br class=""><br class=""><br class="">2) 3.8.1.2. Seqno Requests<br class=""><br class=""> If the requested router-id is not its own, the received request's hop<br class=""> count is 2 or more, and the node has a route (not necessarily a<br class=""> feasible one) for the requested prefix that does not use the<br class=""> requestor as a next hop, the node SHOULD forward the request. It<br class=""> does so by decreasing the hop count and sending the request in a<br class=""> unicast packet destined to a neighbour that advertises the given<br class=""> prefix (not necessarily the selected neighbour) and that is distinct<br class=""> from the neighbour from which the request was received.<br class=""><br class="">I am not sure why the paragraph emphasises 'node has a route (not<br class="">necessarily a feasible one) for the requested prefix that does not use<br class="">the requestor as a next hop' and what means '(not necessarily the<br class="">selected neighbour)', when in earlier paragraphs it is established that<br class="">seqno forwarding is only done if there is a selected route with the same<br class="">router-id.<br class=""><br class="">I guess it is because the selected route may be one with the requestor as<br class="">a next hop and and in such case a different route (with the same router-id)<br class="">has to be used?<br class=""><br class=""><br class="">3) In appendix B, there are no hints about resending and expiration of<br class="">requests - suggested timeout values and number of resend attempts.<br class="">Are there any suggested values?<br class=""><br class="">-- <br class="">Elen sila lumenn' omentielvo<br class=""><br class="">Ondrej 'Santiago' Zajicek (<a href="mailto:santiago@crfreenet.org" class="">email: santiago@crfreenet.org</a>)<br class="">OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, <a href="http://wwwkeys.pgp.net" class="">wwwkeys.pgp.net</a>)<br class="">"To err is human -- to blame it on a computer is even more so."<br class=""><br class=""><br class="">_______________________________________________<br class="">Babel-users mailing list<br class=""><a href="mailto:Babel-users@lists.alioth.debian.org" class="">Babel-users@lists.alioth.debian.org</a><br class="">http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/babel-users</div></blockquote></div><br class=""></div></body></html>