Re: [Bier] BAR field length in draft-ietf-bier-isis-extensions and draft-ietf-bier-ospf-extensions
Tony Przygienda <[email protected]> Wed, 21 Feb 2018 09:43:13 -0800
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--===============0710139865285811631== Content-Type: multipart/alternative; boundary="089e082f6a44844de70565bc78c7" --089e082f6a44844de70565bc78c7 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable First, I concur with Alia's writeup fully and yes, this is definitely providing a "higher ground" and clean architecture what those 16 bits are aiming to achieve if they really should serve their purpose in the oncoming years. Beside providing a nice orthogonal framework to think about those issues it gives BIER the possibility to use the underlying IGP as any combination of (signalling, computation algorithm, constraints) so to speak while we can substitute/add the algorithm and/or constraint part with BIER information/algorithm as needed in each use case. Efficient implementation is a different topic, at minimum we understand it for things like SPF quite well from other technologies. The only thing BIER will never try to do is topology distribution when using IGP of course ;-) If we took all this fire to the forge here to emerge with that framework as consensus, it may have been very well worth it IMO. Second, I concur with Jeffrey terminology-wise that the BART is the BIER algorithm/constraint side normally when we talk about it & BARM the "IGP computation side". We could do BAT & RAT for BIER & ROUTING but I fear that the 2nd acronym is too unfortunate then and we don't capture the constraint part either. So (BC,BA) and (RC,RA) will work fine as well IMO. I see that in a sense as option F) with clear architectural framework and am waiting for the writeup now to nit what's necessary ... thanks --- tony On Wed, Feb 21, 2018 at 7:05 AM, Jeffrey (Zhaohui) Zhang <[email protected]= t > wrote: > Hi Alia, > > > > Thanks for articulating it very clearly, and bring out the issue of havin= g > a clear specification on the interaction. > > > > I need one clarification from you though =E2=80=93 is it possible that th= e you > actually meant BART when you said BARM, and vice versa, in the following? > > > > ------------------ > > With that, the BART can be exactly the IGP Algorithms registry. > > All the IGP Algorithms are available. For the 2 currently defined, the > constraints are empty. > > > > For the BARM, all the necessary constraints can be applied first. > > > > To define a code-point for BARM, the following information is necessary: > > i) Constraints > > ii) Can constraints be additive (default yes unless specified > otherwise) > > iii) What is the algorithm - or is it "empty" > > ------------- > > > > I=E2=80=99ll try to work with Les on the text to specify the interaction. > > > > Jeffrey > > > > *From:* Alia Atlas [mailto:[email protected]] > *Sent:* Wednesday, February 21, 2018 9:45 AM > *To:* Jeffrey (Zhaohui) Zhang <[email protected]> > *Cc:* IJsbrand Wijnands (iwijnand) <[email protected]>; > [email protected] <[email protected]>; > [email protected]; IJsbrand Wijnands <[email protected]>; [email protected]; Eric > Rosen <[email protected]> > > *Subject:* Re: [Bier] BAR field length in draft-ietf-bier-isis-extensions > and draft-ietf-bier-ospf-extensions > > > > First, I greatly appreciate the rapid education I have gotten on why the > different aspects of this are important. > > > > Let us explore some details on the plan for an 8-bit BART and an 8-bit > BARM that are independent. Jeffrey, > > I really appreciate your bringing this option to the list. It simplifies > the option B idea of subtypes away and there > > seems to be a good amount of interest in it. > > > > My concern is that we specify adequately how the codepoints in BART and > BARM interact. > > > > One of the challenges with doing so has been, IMHO, a bit of terminology > where we are describing these as > > algorithms but in fact these are tuples consisting of a set of constraint= s > and a base algorithm. > > > > BART is the BIER layer's constraints (BC) and algorithm (BA). Let us > describe this as BART =3D (BC, BA). > > > > BARM is the Routing layer's constraints (RC) and algorithm (RA). Let us > describe this as BARM =3D (RC, RA). > > > > Let me give some concrete examples. > > > > Consider a case of BART=3D4 which is known to mean (prune non-BIER router= s, > use SPF). > > BARM =3D 200, which is known to mean (prune links with BW <10G, use SPF) > > > > It is desirable to have an outcome that is (prune non-BIER routers and > links with BW < 10G, use SPF). > > > > This can work algorithmically because the constraints are the types that > we've seen before for RSVP-TE. > > > > What I think we need to make the independent 8-bit BART plus 8-bit BARM > work is a clear specification > > of the interaction. I think that is: > > > > Start with the topology Topology. > > 1) Apply the constraints represented by the BART BC(Topology) > > 2) Apply the constraints represented by the BARM RC(BC(Topology)) > > 3) Select the algorithm A as follows: use BA or if BA is "empty", use RA= . > > Run A on RC(BC(Topology)) to get the next-hops and information for th= e > BIFT. > > > > Key points on the algorithm aspect are: > > a) BIER is the higher layer, so it is assumed to know better which > algorithm should be used. > > b) It is possible for BA to be "empty" (as the BARM=3D0 case discussed) = so > that the algorithm > > falls through to whatever is RA. > > > > With that, the BART can be exactly the IGP Algorithms registry. > > All the IGP Algorithms are available. For the 2 currently defined, the > constraints are empty. > > > > For the BARM, all the necessary constraints can be applied first. > > > > To define a code-point for BARM, the following information is necessary: > > i) Constraints > > ii) Can constraints be additive (default yes unless specified > otherwise) > > iii) What is the algorithm - or is it "empty" > > > > I am bringing forth this description now because I am concerned that the > interaction between > > BARM and BART is not adequately defined to be published - but I see the > strong interest in > > this as the solution and, from my understanding of the problem, agree. > > > > Please comment ASAP. > > > > Jeffrey & Les, is this something that you can turn into clear text for th= e > drafts? > > > > Regards, > > Alia > > > > > > > > > > On Wed, Feb 21, 2018 at 9:17 AM, Jeffrey (Zhaohui) Zhang < > [email protected]> wrote: > > To make it absolutely clear using an example: even with <BART 1, BARM 200= > > it is still that the two fields are independent of each other. > > This particular combination means =E2=80=9Capply BART 1=E2=80=9D to =E2= =80=9CFlexible-Algo 200=E2=80=9D, > where =E2=80=9CFlexible-Algo 200=E2=80=9D could be =E2=80=9Cexclude red l= inks=E2=80=9D, while =E2=80=9CBART 1=E2=80=9D > could be =E2=80=9Cskip BIER incapable routers=E2=80=9D. > > > > This is a very practical and concrete example showing the advantage of > having two separate fields. Other ways could be used to achieve the same > result, but they=E2=80=99re more cumbersome. > > > > Jeffrey > > > > *From:* BIER [mailto:[email protected]] *On Behalf Of *IJsbrand > Wijnands (iwijnand) > *Sent:* Wednesday, February 21, 2018 8:40 AM > *To:* Jeffrey (Zhaohui) Zhang <[email protected]> > *Cc:* [email protected]; [email protected]; IJsbrand Wijnands <[email protected]>; > [email protected] <[email protected]>; > Eric Rosen <[email protected]> > *Subject:* Re: [Bier] BAR field length in draft-ietf-bier-isis-extensions > and draft-ietf-bier-ospf-extensions > > > > > > > > Ice: No, BART is not being slaved here. If BARM is 0, BART is all yours. > > > > Zzh> BART is BIER=E2=80=99s no matter what BARM is; not only when BARM is= 0. > > > > Ice: Yes, sorry, I agree, BART is always BIER and BARM is always IGP. > > > > Ice: What I meant to clarify is that BART is not slaved to BARM (IGP) and > v.s., if BART is used, BARM will just be 0. > > > > Thx, > > > > Ice. > > > > > > THx, > > > > Ice. > > > > > > Jeffrey > > > > Registry Algorithm a.k.a as BARM then ... Without this section we would b= e > mandating that BARM is always an IGP algorithm or FA so basically it woul= d > mandate IGP > > > > Ice: Yes, BARM will be the IGP algorithm. That is to accommodate the > people on the list who are of the opinion that aligning with IGP is > important. > > > > Algorithm registry as the only option to perform a calculation making BAR= T > possibly pretty much useless ... Having a registry being mapped 1:1 into > another registry known > > > > Ice: I don't understand why you are saying this. If BARM is 0, BART is al= l > yours. Its unfortunate that a large part of the discussion is dominated b= y > perceived functionality in the form of BIER Algorithm, while there is no > architecture draft that describes how it should work and no discussion ha= s > happen in any IETF meeting, which leaves us all guessing. I think Alia > asked a very good question on the list regarding "constraints". It is not > at all clear if BART is a Algorithm or a Constraint. I think from your > response you're saying its both, which seems wrong IMO.. To me Alia's > question is still open, but that that may be because I could not decipher > the rest of your response. > > > > as identity makes them both them the same thing by another name. > > So, to get anywhere close to consensus let's get bit less creative maybe > and stick to the four letters of the alphabet that the AD extended as a > wide playing field and the WG seems to converge around ... Or otherwise > stick to option F) unmodified and see who's > > interested in it unless you insist on creating an option G) ... > > > > Ice: Jeffrey brought option F to the list in order to discuss it, that is > what we are doing, and that is how you can converge on a solution and rea= ch > consensus. That is better compared to a vote on an option and everybody > walks away with a different interpretation of it. > > > > Thx, > > > > Ice. > > > _______________________________________________ > BIER mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/bier > <https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.ietf.org_mail= man_listinfo_bier&d=3DDwMFaQ&c=3DHAkYuh63rsuhr6Scbfh0UjBXeMK-ndb3voDTXcWzoC= I&r=3Df7wsLGcfzAWDNS6XNTBZwj_OLAOsZZqdrR2IDAzeZqE&m=3D-s4yYMmN1jlRwgyk02_2I= Famu-k7K7di1WiwKt-AoeE&s=3DpJHykwbjl-mkz5oRRkXE6hjOs0tsiC1ucjQtr6-F-4k&e=3D= > > > > > _______________________________________________ > Isis-wg mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/isis-wg > > --089e082f6a44844de70565bc78c7 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div><div><div><div><br></div>First, I concur with Alia= 9;s writeup fully and yes, this is definitely providing a "higher grou= nd" and clean architecture what those 16 bits are aiming to achieve if= they really should serve their purpose in the oncoming years. Beside provi= ding a nice orthogonal framework to think about those issues it gives BIER = the possibility to use the underlying IGP as any combination of (signalling= , computation algorithm, constraints)=C2=A0 so to speak while we can substi= tute/add the algorithm and/or constraint part with BIER information/algorit= hm as needed in each use case. Efficient implementation is a different topi= c, at minimum we understand it for things like SPF quite well from other te= chnologies. The only thing BIER will never try to do is topology distributi= on when using IGP of course=C2=A0 ;-)=C2=A0=C2=A0 If we took all this fire = to the forge here to emerge with that framework as consensus, it may have b= een very well worth it IMO. <br><br>Second, I concur with Jeffrey terminolo= gy-wise that the BART is the BIER algorithm/constraint side normally when we talk about it & BARM the "IGP computation side". We could do BAT & RAT for BIER &= =20 ROUTING but I fear that the 2nd acronym is too unfortunate then and we don&= #39;t capture the constraint part either. So=20 (BC,BA) and (RC,RA) will work fine as well IMO.=C2=A0 <br><br></div>I see t= hat in a sense as option F) with clear architectural framework and am waiti= ng for the writeup now to nit what's necessary ... <br><br></div>thanks= <br><br></div>--- tony <br><div><div><div><br><br><br></div></div></div><d= iv class=3D"gmail_extra"><br><div class=3D"gmail_quote">On Wed, Feb 21, 201= 8 at 7:05 AM, Jeffrey (Zhaohui) Zhang <span dir=3D"ltr"><<a href=3D"mail= to:[email protected]" target=3D"_blank">[email protected]</a>></span> = wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bord= er-left:1px #ccc solid;padding-left:1ex"> <div link=3D"blue" vlink=3D"purple" lang=3D"EN-US"> <div class=3D"m_-6363006900254701974m_4727053652936823113WordSection1"> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">Hi Alia,<u></u><u></u></span></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d"><u></u>=C2=A0<u></u></span></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">Thanks for articulating it very clear= ly, and bring out the issue of having a clear specification on the interact= ion.<u></u><u></u></span></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d"><u></u>=C2=A0<u></u></span></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">I need one clarification from you tho= ugh =E2=80=93 is it possible that the you actually meant BART when you said= BARM, and vice versa, in the following?<u></u><u></u></span></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d"><u></u>=C2=A0<u></u></span></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">------------------<u></u><u></u></spa= n></p><span> <p class=3D"MsoNormal" style=3D"margin-left:.5in">With that, the BART can b= e exactly the IGP Algorithms registry.<u></u><u></u></p> <p class=3D"MsoNormal" style=3D"margin-left:.5in">All the IGP Algorithms ar= e available.=C2=A0 =C2=A0For the 2 currently defined, the constraints are e= mpty.<u></u><u></u></p> <p class=3D"MsoNormal" style=3D"margin-left:.5in"><u></u>=C2=A0<u></u></p> <p class=3D"MsoNormal" style=3D"margin-left:.5in">For the BARM, all the nec= essary constraints can be applied first.<u></u><u></u></p> <p class=3D"MsoNormal" style=3D"margin-left:.5in"><u></u>=C2=A0<u></u></p> <p class=3D"MsoNormal" style=3D"margin-left:.5in">To define a code-point fo= r BARM, the following information is necessary:<u></u><u></u></p> <p class=3D"MsoNormal" style=3D"margin-left:.5in">=C2=A0 =C2=A0<span class= =3D"m_-6363006900254701974m_4727053652936823113SpellE">i</span>) Constraint= s<u></u><u></u></p> <p class=3D"MsoNormal" style=3D"margin-left:.5in">=C2=A0 =C2=A0ii) Can cons= traints be additive=C2=A0 (default <span class=3D"m_-6363006900254701974m_4727053652936823113SpellE">yes</span= > unless specified otherwise)<u></u><u></u></p> <p class=3D"MsoNormal" style=3D"margin-left:.5in">=C2=A0 =C2=A0iii) What is= the algorithm - or is it "empty"<u></u><u></u></p> </span><p class=3D"MsoNormal">-------------<u></u><u></u></p> <p class=3D"MsoNormal"><a name=3D"m_-6363006900254701974_m_4727053652936823= 113__MailEndCompose"><span style=3D"font-size:11.0pt;font-family:"Cali= bri",sans-serif;color:#1f497d"><u></u>=C2=A0<u></u></span></a></p> <p class=3D"MsoNormal"><span><span style=3D"font-size:11.0pt;font-family:&q= uot;Calibri",sans-serif;color:#1f497d">I=E2=80=99ll try to work with L= es on the text to specify the interaction.<u></u><u></u></span></span></p> <p class=3D"MsoNormal"><span><span style=3D"font-size:11.0pt;font-family:&q= uot;Calibri",sans-serif;color:#1f497d"><u></u>=C2=A0<u></u></span></sp= an></p> <p class=3D"MsoNormal"><span><span style=3D"font-size:11.0pt;font-family:&q= uot;Calibri",sans-serif;color:#1f497d">Jeffrey<u></u><u></u></span></s= pan></p> <p class=3D"MsoNormal"><span><span style=3D"font-size:11.0pt;font-family:&q= uot;Calibri",sans-serif;color:#1f497d"><u></u>=C2=A0<u></u></span></sp= an></p> <span></span> <div style=3D"border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in = 4.0pt"> <div> <div style=3D"border:none;border-top:solid #e1e1e1 1.0pt;padding:3.0pt 0in = 0in 0in"> <p class=3D"MsoNormal"><b><span style=3D"font-size:11.0pt;font-family:"= ;Calibri",sans-serif">From:</span></b><span style=3D"font-size:11.0pt;= font-family:"Calibri",sans-serif"> Alia Atlas [mailto:<a href=3D"mailto:[email protected]" target=3D"_blank">akatl= [email protected]</a>] <br> <b>Sent:</b> Wednesday, February 21, 2018 9:45 AM<span><br> <b>To:</b> Jeffrey (Zhaohui) Zhang <<a href=3D"mailto:[email protected]= " target=3D"_blank">[email protected]</a>><br> </span><b>Cc:</b> IJsbrand Wijnands (iwijnand) <<a href=3D"mailto:iwijna= [email protected]" target=3D"_blank">[email protected]</a>>; <a href=3D"mail= to:[email protected]" target=3D"_blank">EXT-arkadiy.gulk= o@thomsonreute<wbr>rs.com</a> <<a href=3D"mailto:arkadiy.gulko@thomsonre= uters.com" target=3D"_blank">arkadiy.gulko@thomsonreuters.<wbr>com</a>>;= <a href=3D"mailto:[email protected]" target=3D"_blank">[email protected]</a>; IJsb= rand Wijnands <<a href=3D"mailto:[email protected]" target=3D"_blank">ice@ci= sco.com</a>>; <a href=3D"mailto:[email protected]" target=3D"_blank">isis= [email protected]</a>; Eric Rosen <<a href=3D"mailto:[email protected]" targ= et=3D"_blank">[email protected]</a>></span></p><div><div class=3D"m_-63= 63006900254701974h5"><br> <b>Subject:</b> Re: [Bier] BAR field length in draft-ietf-bier-isis-extensi= on<wbr>s and draft-ietf-bier-ospf-extension<wbr>s<u></u><u></u></div></div>= <p></p> </div> </div><div><div class=3D"m_-6363006900254701974h5"> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> <div> <p class=3D"MsoNormal">First, I greatly appreciate the rapid education I ha= ve gotten on why the different aspects of this are important.<u></u><u></u>= </p> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">Let us explore some details on the plan for an 8-bit= BART and an 8-bit BARM that are independent.=C2=A0 Jeffrey,<u></u><u></u><= /p> </div> <div> <p class=3D"MsoNormal">I really appreciate your bringing this option to the= list.=C2=A0 It simplifies the option B idea of subtypes away and there<u><= /u><u></u></p> </div> <div> <p class=3D"MsoNormal">seems to be a good amount of interest in it.<u></u><= u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">My concern is that we specify adequately how the cod= epoints in BART and BARM interact.=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">One of the challenges with doing so has been, IMHO, = a bit of terminology where we are describing these as<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">algorithms but in fact these are tuples consisting o= f a set of constraints and a base algorithm.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">BART is the BIER layer's constraints (BC) and al= gorithm (BA).=C2=A0 Let us describe this as BART =3D=C2=A0 (BC, BA).<u></u>= <u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">BARM is the Routing layer's constraints (RC) and= algorithm (RA).=C2=A0 Let us describe this as BARM =3D (RC, RA).<u></u><u>= </u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">Let me give some concrete examples.<u></u><u></u></p= > </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">Consider a case of BART=3D4 which is known to mean (= prune non-BIER routers, use SPF).<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">BARM =3D 200, which is known to mean (prune links wi= th BW <10G, use SPF)<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">It is desirable to have an outcome that is (prune no= n-BIER routers and links with BW < 10G, use SPF).<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">This can work algorithmically because the constraint= s are the types that we've seen before for RSVP-TE.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">What I think we need to make the independent 8-bit B= ART plus 8-bit BARM work is a clear specification<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">of the interaction. I think that is:<u></u><u></u></= p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">Start with the topology Topology.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">1) Apply the constraints represented by the BART=C2= =A0 BC(Topology)<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">2) Apply the constraints represented by the BARM=C2= =A0 RC(BC(Topology))<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">3) Select the algorithm A as follows:=C2=A0 use BA o= r if BA is "empty", use RA.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">=C2=A0 =C2=A0 Run A on RC(BC(Topology)) to get the n= ext-hops and information for the BIFT.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">Key points on the algorithm aspect are:<u></u><u></u= ></p> </div> <div> <p class=3D"MsoNormal">a) BIER is the higher layer, so it is assumed to kno= w better which algorithm should be used.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">b) It is possible for BA to be "empty"=C2= =A0 (as the BARM=3D0 case discussed) so that the algorithm<u></u><u></u></p= > </div> <div> <p class=3D"MsoNormal">=C2=A0 =C2=A0 falls through to whatever is RA.<u></u= ><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">With that, the BART can be exactly the IGP Algorithm= s registry.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">All the IGP Algorithms are available.=C2=A0 =C2=A0Fo= r the 2 currently defined, the constraints are empty.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">For the BARM, all the necessary constraints can be a= pplied first.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">To define a code-point for BARM, the following infor= mation is necessary:<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">=C2=A0 =C2=A0i) Constraints<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">=C2=A0 =C2=A0ii) Can constraints be additive=C2=A0 (= default yes unless specified otherwise)<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">=C2=A0 =C2=A0iii) What is the algorithm - or is it &= quot;empty"<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">I am bringing forth this description now because I a= m concerned that the interaction between<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">BARM and BART is not adequately defined to be publis= hed - but I see the strong interest in<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">this as the solution and, from my understanding of t= he problem, agree.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">Please comment ASAP.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">Jeffrey & Les, is this something that you can tu= rn into clear text for the drafts?<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">Regards,<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Alia<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> <div> <p class=3D"MsoNormal">=C2=A0 =C2=A0=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> </div> <div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> <div> <p class=3D"MsoNormal">On Wed, Feb 21, 2018 at 9:17 AM, Jeffrey (Zhaohui) Z= hang <<a href=3D"mailto:[email protected]" target=3D"_blank">zzhang@jun= iper.net</a>> wrote:<u></u><u></u></p> <blockquote style=3D"border:none;border-left:solid #cccccc 1.0pt;padding:0i= n 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in"> <div> <div> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">To make it absolutely clear using an = example: even with <BART 1, BARM 200> it is still that the two fields are independent of each other.</span><u></u><u></u></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">This particular combination means =E2= =80=9Capply BART 1=E2=80=9D to =E2=80=9CFlexible-<span class=3D"m_-63630069= 00254701974m_4727053652936823113m8474473347374251652spelle">Algo</span> 200=E2=80=9D, where =E2=80=9CFlexible-<span class=3D"m_-636300690025470197= 4m_4727053652936823113m8474473347374251652spelle">Algo</span> 200=E2=80=9D = could be =E2=80=9Cexclude red links=E2=80=9D, while =E2=80=9CBART 1=E2=80= =9D could be =E2=80=9Cskip BIER incapable routers=E2=80=9D.</span><u></u><u= ></u></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">=C2=A0</span><u></u><u></u></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">This is a very practical and concrete= example showing the advantage of having two separate fields. Other ways could be used to achieve the same result, but they=E2=80=99re m= ore cumbersome.</span><u></u><u></u></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">=C2=A0</span><u></u><u></u></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">Jeffrey</span><u></u><u></u></p> <p class=3D"MsoNormal"><a name=3D"m_-6363006900254701974_m_4727053652936823= 113_m_8474473347374251652__MailEndCompose"><span style=3D"font-size:11.0pt;= font-family:"Calibri",sans-serif;color:#1f497d">=C2=A0</span></a>= <u></u><u></u></p> <div style=3D"border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in = 4.0pt"> <div> <div style=3D"border:none;border-top:solid #e1e1e1 1.0pt;padding:3.0pt 0in = 0in 0in"> <p class=3D"MsoNormal"> <b><span style=3D"font-size:11.0pt;font-family:"Calibri",sans-ser= if">From:</span></b><span style=3D"font-size:11.0pt;font-family:"Calib= ri",sans-serif"> BIER [mailto:<a href=3D"mailto:[email protected]"= target=3D"_blank">[email protected]</a>] <b>On Behalf Of </b>IJsbrand Wijnands (iwijnand)<br> <b>Sent:</b> Wednesday, February 21, 2018 8:40 AM<br> <b>To:</b> Jeffrey (Zhaohui) Zhang <<a href=3D"mailto:[email protected]= " target=3D"_blank">[email protected]</a>><br> <b>Cc:</b> <a href=3D"mailto:[email protected]" target=3D"_blank">[email protected]= </a>; <a href=3D"mailto:[email protected]" target=3D"_blank"> [email protected]</a>; IJsbrand Wijnands <<a href=3D"mailto:[email protected]= " target=3D"_blank">[email protected]</a>>; <a href=3D"mailto:[email protected]" target=3D"_blank">E= XT-arkadiy.gulko@thomsonreute<wbr>rs.com</a> <<a href=3D"mailto:arkadiy.= [email protected]" target=3D"_blank">arkadiy.gulko@thomsonreuters.<w= br>com</a>>; Eric Rosen <<a href=3D"mailto:[email protected]" target= =3D"_blank">[email protected]</a>><br> <b>Subject:</b> Re: [Bier] BAR field length in draft-ietf-bier-isis-extensi= on<wbr>s and draft-ietf-bier-ospf-extension<wbr>s</span><u></u><u></u></p> </div> </div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <blockquote style=3D"margin-top:5.0pt;margin-bottom:5.0pt"> <blockquote style=3D"margin-top:5.0pt;margin-bottom:5.0pt"> <div> <div> <div style=3D"border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in = 4.0pt"> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Ice: No, BART is not being slaved here. If BARM is 0= , BART is all yours.<u></u><u></u></p> </div> <div> <div> <p class=3D"MsoNormal"><span style=3D"color:#1f497d">=C2=A0</span><u></u><u= ></u></p> <p class=3D"MsoNormal"><span class=3D"m_-6363006900254701974m_4727053652936= 823113m8474473347374251652spelle"><span style=3D"font-size:11.0pt;font-fami= ly:"Calibri",sans-serif;color:#1f497d">Zzh</span></span><span sty= le=3D"font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f= 497d">> BART is BIER=E2=80=99s no matter what BARM is; not only when BARM is 0.</s= pan><u></u><u></u></p> </div> </div> </div> </div> </div> </blockquote> <div> <div> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Ice: Yes, sorry, I agree, BART is always BIER and BA= RM is always IGP.<u></u><u></u></p> </div> </div> </div> </blockquote> <div> <div> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Ice: What I meant to clarify is that BART is not sla= ved to BARM (IGP) and v.s., if BART is used, BARM will just be 0.<u></u><u>= </u></p> </div> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Thx,<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Ice.<u></u><u></u></p> </div> <p class=3D"MsoNormal" style=3D"margin-bottom:12.0pt"><u></u>=C2=A0<u></u><= /p> <blockquote style=3D"margin-top:5.0pt;margin-bottom:5.0pt"> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">THx,<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Ice.<u></u><u></u></p> </div> <p class=3D"MsoNormal" style=3D"margin-bottom:12.0pt"><u></u>=C2=A0<u></u><= /p> <blockquote style=3D"margin-top:5.0pt;margin-bottom:5.0pt"> <div> <div> <div style=3D"border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in = 4.0pt"> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">=C2=A0</span><u></u><u></u></p> <p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:"Ca= libri",sans-serif;color:#1f497d">Jeffrey</span><u></u><u></u></p> <p class=3D"MsoNormal" style=3D"margin-bottom:12.0pt"><u></u>=C2=A0<u></u><= /p> <blockquote style=3D"margin-top:5.0pt;margin-bottom:5.0pt"> <div> <div> <div> <div> <div> <p class=3D"MsoNormal">Registry Algorithm a.k.a as BARM then ... Without th= is section we would be mandating that BARM is always an IGP algorithm or FA= so basically it would mandate IGP <u></u><u></u></p> </div> </div> </div> </div> </div> </blockquote> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Ice: Yes, BARM will be the IGP algorithm. That is to= accommodate the people on the list who are of the opinion that aligning wi= th IGP is important.=C2=A0<u></u><u></u></p> </div> <p class=3D"MsoNormal" style=3D"margin-bottom:12.0pt"><u></u>=C2=A0<u></u><= /p> <blockquote style=3D"margin-top:5.0pt;margin-bottom:5.0pt"> <div> <div> <div> <div> <div> <p class=3D"MsoNormal">Algorithm registry as the only option to perform a c= alculation making BART possibly pretty much useless ... Having a registry b= eing mapped 1:1 into=C2=A0 another registry known <u></u><u></u></p> </div> </div> </div> </div> </div> </blockquote> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Ice: I don't understand why you are saying this.= If BARM is 0, BART is all yours. Its unfortunate that a large part of the = discussion is dominated by perceived functionality in the form of BIER Algorithm, while there is no architecture draft that desc= ribes how it should work and no discussion has happen in any IETF meeting, = which leaves us all guessing. I think Alia asked a very good question on th= e list regarding "constraints". It is not at all clear if BART is a Algorithm or a Constraint. I think fro= m your response you're saying its both, which seems wrong IMO.. To me A= lia's question is still open, but that that may be because I could not = decipher the rest of your response.<u></u><u></u></p> </div> <p class=3D"MsoNormal" style=3D"margin-bottom:12.0pt"><u></u>=C2=A0<u></u><= /p> <blockquote style=3D"margin-top:5.0pt;margin-bottom:5.0pt"> <div> <div> <div> <div> <div> <p class=3D"MsoNormal" style=3D"margin-bottom:12.0pt">as identity makes the= m both them the same thing by another name. <u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">So, to get anywhere close to consensus let's get= bit less creative maybe and stick to the four letters of the alphabet that= the AD extended as a wide playing field and the WG seems to converge around ... Or otherwise stick to option F) unmodified and see = who's<u></u><u></u></p> </div> </div> </div> </div> </div> </blockquote> <blockquote style=3D"margin-top:5.0pt;margin-bottom:5.0pt"> <div> <div> <div> <div> <div> <p class=3D"MsoNormal">interested in it unless you insist on creating an op= tion G) ... <u></u><u></u></p> </div> </div> </div> </div> </div> </blockquote> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Ice: Jeffrey brought option F to the list in order t= o discuss it, that is what we are doing, and that is how you can converge o= n a solution and reach consensus. That is better compared to a vote on an option and everybody walks away with a different interpret= ation of it.<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Thx,<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">=C2=A0<u></u><u></u></p> </div> <div> <p class=3D"MsoNormal">Ice.<u></u><u></u></p> </div> </div> </div> </div> </blockquote> </blockquote> </div> </div> </div> </div> </div> <p class=3D"MsoNormal" style=3D"margin-bottom:12.0pt"><br> ______________________________<wbr>_________________<br> BIER mailing list<br> <a href=3D"mailto:[email protected]" target=3D"_blank">[email protected]</a><br> <a href=3D"https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.ietf.= org_mailman_listinfo_bier&d=3DDwMFaQ&c=3DHAkYuh63rsuhr6Scbfh0UjBXeM= K-ndb3voDTXcWzoCI&r=3Df7wsLGcfzAWDNS6XNTBZwj_OLAOsZZqdrR2IDAzeZqE&m= =3D-s4yYMmN1jlRwgyk02_2IFamu-k7K7di1WiwKt-AoeE&s=3DpJHykwbjl-mkz5oRRkXE= 6hjOs0tsiC1ucjQtr6-F-4k&e=3D" target=3D"_blank">https://www.ietf.org/ma= ilman/l<wbr>istinfo/bier</a><u></u><u></u></p> </blockquote> </div> <p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p> </div> </div></div></div> </div> </div> <br>______________________________<wbr>_________________<br> Isis-wg mailing list<br> <a href=3D"mailto:[email protected]" target=3D"_blank">[email protected]</a><= br> <a href=3D"https://www.ietf.org/mailman/listinfo/isis-wg" rel=3D"noreferrer= " target=3D"_blank">https://www.ietf.org/mailman/l<wbr>istinfo/isis-wg</a><= br> <br></blockquote></div><br></div></div> --089e082f6a44844de70565bc78c7-- --===============0710139865285811631== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Isis-wg mailing list [email protected] https://www.ietf.org/mailman/listinfo/isis-wg --===============0710139865285811631==--