From nobody Fri Oct 22 00:34:14 2021 Return-Path: X-Original-To: rift@ietfa.amsl.com Delivered-To: rift@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 725D73A085C for ; Fri, 22 Oct 2021 00:34:06 -0700 (PDT) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -2.096 X-Spam-Level: X-Spam-Status: No, score=-2.096 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, HTML_FONT_FACE_BAD=0.001, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=unavailable autolearn_force=no Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id hoO8yAFbFfAN for ; Fri, 22 Oct 2021 00:34:02 -0700 (PDT) Received: from mail-il1-x136.google.com (mail-il1-x136.google.com [IPv6:2607:f8b0:4864:20::136]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 026C23A0860 for ; Fri, 22 Oct 2021 00:33:52 -0700 (PDT) Received: by mail-il1-x136.google.com with SMTP id j3so3311601ilr.6 for ; Fri, 22 Oct 2021 00:33:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=PWnwTewUt74lzYAEimYhHFh9sDFaZXDu3PfMbKL+2mA=; b=V4tITctuj3ojficxHxiqtw+5u4mW7trU5JzzxOdrwR56cPPOeC3bSWNwMt6VaBbNkN G3XIjXc3JLR1fBf+uK3Oi7SB+PvOREduLL9vp+wwA5I7x6TIyBITzP8z8YniiysqLy5f QnQOCnPBvb5N5BD9NrTkllwa9unEUtu8uBkp/pAIrtvLTs0gWpQoTAvGDHQ7/2tC1CfY WCyO971p9vda9U5wQhYCeJeRb7pgUaf0GWUh9IJCBgejBgw1p+LE/dFhs0Ovpl/93n6x IjuBgygrNJJeLm89Ib0M431xPhx+NfhnaOjkMQze5QXiifbDIZxIEQGZMtiz5JNd/SFy uVMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=PWnwTewUt74lzYAEimYhHFh9sDFaZXDu3PfMbKL+2mA=; b=0gAMPL2i+y9DfZ1Kd6jACzMtIZA6+LyQFszgszttYHv5F2Ngaif+QuhRJ/5sDDCDA0 40y/CD3s3gYoekGLOvOBl7EgOP7J7hpulZX0NzG4Av8NPz6qmnFFCVQ7UuO4KAXE0OzD 8jdBMrOPIUMkvaA5ZuwwOeqJm2QSeRdWwDvnHZdUVICphckJAVShJAV0CLcSxjjA6iHi 8GciIXTuzDgUrVgXzeiNueCdWa7jfVQkQLHPA4X6FiXV12sYJ7hsPUlfj+xxueo6UfOQ G+fa+3/bpNwIv1I0jxV0/Q89+eEdjramIdRsikUIcu/BrP5UxxrYwhhYxzZPIP97Dd1H oeXQ== X-Gm-Message-State: AOAM532aEMvoGed3Fx/W9HIgCXcE6PLVV7YO6R9Q9vrnE8+tl5wZoVzE jxunqt1+bLxe2FZG0dP9BSZmj/sr7lwSOA4+hSI= X-Google-Smtp-Source: ABdhPJx+PNzZmtfvWXX95UOvbi76NujBZ61SD/Md/kYghHHVF/cXOtU4cLYCppmdCzt9eyWkCSNUMvpm5CM5W0Unpsg= X-Received: by 2002:a05:6e02:20e7:: with SMTP id q7mr7194709ilv.254.1634888030830; Fri, 22 Oct 2021 00:33:50 -0700 (PDT) MIME-Version: 1.0 References: <202110220942126173826@zte.com.cn> In-Reply-To: <202110220942126173826@zte.com.cn> From: Tony Przygienda Date: Fri, 22 Oct 2021 09:33:14 +0200 Message-ID: To: wei.yuehua@zte.com.cn Cc: "Jeffrey (Zhaohui) Zhang" , Antoni Przygienda , rift@ietf.org Content-Type: multipart/alternative; boundary="0000000000005344c905ceec0890" Archived-At: Subject: Re: [Rift] Shepherd review of draft-ietf-rift-applicability X-BeenThere: rift@ietf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion of Routing in Fat Trees List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 22 Oct 2021 07:34:07 -0000 --0000000000005344c905ceec0890 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, Oct 22, 2021 at 3:42 AM wrote: > Dear Toni, Jeffrey, and RIFTers, > > Follow up comment resolutions: > > > They tend to need extensive configuration or provisioning during > bring up and re-dimensioning. > > so=EF=BC=8C will replace =E2=80=9Cre-dimensioning=E2=80=9Dto= "scaling"?> > somehthing like this or just say "adding or removing switching elements from the fabric" > > * Can utilize all paths through fabric without looping > ... > * Supports non-equal cost multipath ... > > Aren't the above two the same/related? > > keep > "* Can utilize all paths through fabric without looping", remove > " * Supports non-equal cost multipath ..." > as I wrote "all paths without looping". take any variation you like that says that > > The "but" wording in the following is a bit strange: > > ... it is > recommended to configure the level of all the nodes but those that > are forced as leaves to avoid an undesirable interaction between ZTP > and the manual configuration. > > > Do you mean "those that are forced as leaves" do not need configuration? = But then how are they "forced as leaves" w/o configuration? > > will delete " but those that are forced as leaves ". > > it should read more "forced as leaves to avoid formation of undesirable topologies" > > > *Best Regards,* > > > > *Yuehua Wei* > > M: +86 13851460269 E: wei.yuehua@zte.com.cn > > > =E5=8E=9F=E5=A7=8B=E9=82=AE=E4=BB=B6 > *=E5=8F=91=E4=BB=B6=E4=BA=BA=EF=BC=9A*TonyPrzygienda > *=E6=94=B6=E4=BB=B6=E4=BA=BA=EF=BC=9A*=E9=AD=8F=E6=9C=88=E5=8D=8E00019655= ; > *=E6=8A=84=E9=80=81=E4=BA=BA=EF=BC=9A*Jeffrey (Zhaohui) Zhang;Antoni Przy= gienda;rift@ietf.org; > *=E6=97=A5 =E6=9C=9F =EF=BC=9A*2021=E5=B9=B410=E6=9C=8821=E6=97=A5 23:35 > *=E4=B8=BB =E9=A2=98 =EF=BC=9A**Re: [Rift] Shepherd review of draft-ietf-= rift-applicability* > inline > > On Thu, Oct 21, 2021 at 10:07 AM wrote: > >> Dear Jeffrey and Toni, >> >> Please see my comments resolution in line start with "> >> Would like Toni to look at , as well. >> >> Thank you! >> >> >> *Best Regards,* >> >> *Yuehua Wei* >> >> *ZTE Corporation* >> >> M: +86 13851460269 E: wei.yuehua@zte.com.cn >> >> >> =E5=8E=9F=E5=A7=8B=E9=82=AE=E4=BB=B6 >> *=E5=8F=91=E4=BB=B6=E4=BA=BA=EF=BC=9A*Jeffrey(Zhaohui)Zhang >> *=E6=94=B6=E4=BB=B6=E4=BA=BA=EF=BC=9A*draft-ietf-rift-applicability@ietf= .org; >> *=E6=8A=84=E9=80=81=E4=BA=BA=EF=BC=9A*'rift@ietf.org'; >> *=E6=97=A5 =E6=9C=9F =EF=BC=9A*2021=E5=B9=B409=E6=9C=8825=E6=97=A5 09:02 >> *=E4=B8=BB =E9=A2=98 =EF=BC=9A**[Rift] Shepherd review of draft-ietf-rif= t-applicability* >> Hi, >> >> >> As part of the shepherd review, I have the following questions/comments.= Some are minor editorial nits. >> >> Node TIE should NOT be confused with a North >> TIE since "node" defines the type of TIE rather than its direction. >> >> Should this be the following? >> >> N-TIE should not be confused with a Node TIE - the "N-" denotes >> "North-" not "Node-". >> >> Yes> >> >> >> For the following: >> >> This is an acronym for a "Prefix Topology Information Element" and it >> contains all prefixes directly attached to this node in case of a >> North TIE and in case of South TIE the necessary default routes the >> node advertises southbound. >> >> Should "default routes" be "default and disaggregated routes"? >> >> the discription of this acronym is copied from rift-rift, >> shall I keep it the same with rift-rift? > >> >> ... RIFT can employ to ultimately >> calculate routes of which Dijkstra algorithm is a possible one. >> >> The above does not read well to me. Is some wording missing? >> >> the discription of this acronym is also copied from >> rift-rift, shall I keep it the same with rift-rift? > >> >> Clos [CLOS] topologies (called commonly a fat tree/network in modern >> IP fabric considerations as homonym to the original definition of the >> term Fat Tree [FATTREE])have gained prominence in today's networking, >> >> Missing a " " in the last line. >> >> Accepted > >> >> >> c protocols were geared towards a network with >> an irregular topology with isotropic properties, and low degree of >> connectivity. >> >> >> "Today's current ... were" sounds strange. How about "Other routing prot= ocols are"? >> >> How about "The current routing protocols are......." ?> >> >> >> * They tend to need extensive configuration or provisioning during >> bring up and re-dimensioning. >> >> "re-dimensioning" lacks context. What does it mean? "reconfiguration"? >> >> it comes from Toni's presentation. I think it means >> "scaling", Would like to call Toni for comfirmation=EF=BC=8Cthanks > >> > > well, when you add or remove switches/PoD etc > >> >> >> The N-TIEs contain a link-state topology description of lower levels >> and S-TIEs carry simply default routes for the lower levels. >> >> "default and disaggregated routes"? >> >> the same as YuehuaWei1> >> > > correct > >> >> >> RIFT also eliminates major disadvantages of link-state and distance- >> vector with: >> * Reduced and balanced flooding >> * Automatic neighbor detection >> >> Does link-state routing not have auto neighbor detection? >> >> How about changing to=E2=80=9CLevel constrained >> automatic neighbor detection=E2=80=9D=EF=BC=9F Would like to ask for Ton= i's comments > >> > > agreed > >> >> >> * Can utilize all paths through fabric without looping >> ... >> * Supports non-equal cost multipath ... >> >> Aren't the above two the same/related? >> >> I think the two above are nearly the same . Since "loop >> free" has been stated in other part of the document. I would like to del= ete >> "Can utilize all paths through fabric without looping"> >> > > yes, in a sense it's the same, I would just stick to "utilize all paths i= n > loop-free fashion" > >> >> >> 4.2.1. Horizontal Links >> >> RIFT is not limited to pure Clos divided into PoD and multi-planes >> but supports horizontal (East-West) links below the top of fabric >> level. Those links are used only for last resort northbound routes >> when a spine loses all its northbound links or cannot compute a >> default route through them. >> >> A possible configuration is a "ring" of horizontal links at a level. >> In presence of such a "ring" in any level (except Top of Fabric (ToF) >> level) neither North SPF (N-SPF) nor South SPF (S-SPF) will provide a >> "ring-based protection" scheme since such a computation would have to >> deal necessarily with breaking of "loops" in Dijkstra sense; an >> application for which RIFT is not intended. >> >> A full-mesh connectivity between nodes on the same level can be >> employed and that allows N-SPF to provide for any node loosing all >> its northbound adjacencies (as long as any of the other nodes in the >> level are northbound connected) to still participate in northbound >> forwarding. >> >> >> I struggled a bit with the second paragraph above. Is the following unde= rstanding of all three paragraphs correct? >> >> >> 1. east-west links below TOF provide last resort northbound routes (1st = paragraph) - BTW should it be "northbound forwarding" instead of "northboun= d route"? >> >> 2. a full mesh east-west links between nodes at the same level provides = last resort northbound forwarding for all the nodes (3rd paragraph) (extend= ing on #1) >> >> 3. however, a ring of horizontal links does not provide ring-based prote= ction (2nd paragraph) >> >> >> If so, it may be better to move the 3rd paragraph up, and change the pre= vious 2nd paragraph to the following: >> >> Note that a "ring" of horizontal links at any level below ToF does >> not provide a "ring-based protection" scheme since the SPF computatio= n >> >> would have to deal necessarily with breaking of "loops" in Dijkstra s= ense - an >> application for which RIFT is not intended. >> >> reasonable, Accepted. will replace >> "northbound forwarding" with "northbound route", and switch 2nd paragrap= h >> and 3rd paragraph.> >> > > in fact such forwarding can be implemented but accepted, we don't want to > go down that route ;-) > >> >> >> In the following: >> >> * Southbound, RIFT operates as a distance-vector protocol, whereby >> the control packets are flooded only one-hop, interpreted, and the >> consequence of that computation is what gets flooded one more hop >> south. In the most common use-cases, a ToF node can reach most of >> the prefixes in the fabric. If that is the case, the ToF node >> advertises the fabric default and disaggregates the prefixes that >> it cannot reach. >> >> Perhaps changing "consequence" to "result"? >> >> Reasonable=EF=BC=8Caccepted> >> >> >> In the last sentence, perhaps say "negatively disaggregates" (if I under= stand it correctly)? >> Reasonable=EF=BC=8Caccepted > >> >> In the general case, what gets advertised south is in more >> details: >> >> >> Perhaps change to "... what get advertised south are:"? (remove the "in = more details") >> >> Reasonable=EF=BC=8Caccepted > >> >> 4.2.3. Generalizing to any Directed Acyclic Graph >> >> RIFT is an anisotropic routing protocol, meaning that it has a sense >> of direction (northbound, southbound, east-west) and that it operates >> differently depending on the direction. >> ... >> A Directed Acyclic Graph (DAG) provides a sense of north (the >> direction of the DAG) and of south (the reverse), which can be used >> to apply RIFT. For the purpose of RIFT, an edge in the DAG that has >> only incoming vertices is a ToF node. >> >> >> I initially struggled a bit with the second paragraph above. Connecting = to the section title, perhaps the following wording is better: >> >> Since a Directed Acyclic Graph (DAG) provides a sense of north (the >> direction of the DAG) and of south (the reverse), it can be used to >> apply RIFT =E2=80=94 an edge in the DAG that has only incoming vertic= es is a >> ToF node. >> >> Reasonable=EF=BC=8Caccepted. will change the En dash (= =E2=80=93) to Em >> dash(=E2=80=94)> >> >> In the following: >> >> RIFT is not strictly limited to Clos topologies. The protocol only >> requires a sense of "compass rose directionality" either achieved >> through configuration or derivation of levels. So, conceptually, >> shortcuts between levels could be included. Figure 2 depicts an >> example of a shortcut between levels. In this example, sub-optimal >> routing will occur when traffic is sent from L0 to L1 via S0's >> default route and back down through A0 or A1. In order to ensure >> that, only default routes from A0 or A1 are used, all leaves would be >> required to install each others routes. >> >> Should "ensure" be "avoid"? >> >> Right=EF=BC=8Caccepted. > >> >> Commercial edifices are often cabled in topologies that are either >> Clos or its isomorphic equivalents. The Clos can grow rather high >> with many floors. >> >> >> If I understand it correctly, better change "floors" to "levels". We're = talking about commercial buildings here, so "floor" may be confused as "bui= lding floors", which I don't think it is referring to. >> >> Reasonable=EF=BC=8Caccepted. > >> >> RIFT is neither IP specific and hence any link addressing >> connecting internal device subnets is conceivable. >> >> s/neither/not/ >> >> Right=EF=BC=8Caccepted. > >> >> * RIFT negotiates automatically BFD per link allowing this way for >> IP and micro-BFD [RFC7130] to replace Link Aggregation Groups >> (LAGs) which do hide bandwidth imbalances in case of constituent >> >> failures. >> >> >> I find it a bit hard to parse the above. Perhaps break it down a bit? >> >> Would like to change to the following wording: >> >> RIFT MAY incorporate BFD [RFC5881] to react quickly to link >> failures. After RIFT ThreeWay hello adjacency convergence a BFD session = MAY >> >> be formed automatically between the RIFT endpoints without further >> >> configuration using the exchanged discriminators. > >> >> Without disaggregation mechanism, when linkSL6 fails, the packet from >> leaf121 to prefix122 will probably go up through linkSL5 to linkTS3 >> then go down through linkTS4 to linkSL8 to Leaf122 or go up through >> linkSL5 to linkTS6 then go down through linkTS4 and linkSL8 to >> Leaf122 based on pure default route. It's the case of suboptimal >> routing or bow-tieing. >> >> I think it should be changed to the following: >> >> Without disaggregation mechanism, when linkSL6 fails, the packet from >> leaf121 to prefix122 *may* go up through linkSL5 to linkTS3 >> then go down through linkTS4 to linkSL8 to Leaf122 or go up through >> linkSL5 to linkTS6 then go down through *linkTS8* and linkSL8 to >> Leaf122 based on pure default route. *This is* the case of suboptima= l >> routing or bow-tieing. >> >> The '*' mark the changes. The second change is to fix a mistake (I think= ). >> >> linkTS3 is connectiong to ToF21, so the downlinks >> are linkTS4 + linkSL8. you were thinking of linkTS6 to ToF22. I think >> both are right >> >> will change *may* and *This is* > >> >> It's the case of black-holing. >> >> s/It's/This is/ >> >> OK=EF=BC=8Caccepted. > >> >> ... that is, on the one >> hand, the SystemID of the node that must be unique in the RIFT >> network, and on the other hand the level of the node in the Fat Tree, >> which determines which peers are northwards "parents" and which are >> southwards "children". >> >> Perhaps change to the following: >> >> ... including SystemID of the node that must be unique in the RIFT >> network and the level of the node in the Fat Tree, >> which determines which peers are northwards "parents" and which are >> southwards "children". >> >> OK=EF=BC=8Caccepted. > >> >> >> The "but" wording in the following is a bit strange: >> >> ... it is >> recommended to configure the level of all the nodes but those that >> are forced as leaves to avoid an undesirable interaction between ZTP >> and the manual configuration. >> >> >> Do you mean "those that are forced as leaves" do not need configuration?= But then how are they "forced as leaves" w/o configuration? >> >> =E5=90=AF=E7=94=A8zte=E7=9A=84=E6=97=B6=E5=80=99=EF=BC= =8Cleaf=E8=8A=82=E7=82=B9=E6=98=AF=E9=9C=80=E8=A6=81=E9=85=8D=E7=BD=AElevel= =E7=9A=84=EF=BC=9F> >> > > ??? ;-) > > A RIFT node may also be configured to confine it to the leaf role >> with the LEAF_ONLY flag. A leaf node can also be configured to >> support leaf-2-leaf procedures with the LEAF_2_LEAF flag. In either >> case the node cannot be TOP_OF_FABRIC and its level cannot be >> configured. RIFT will fully configure the node's level after it is >> attached to the topology and ensure that the node is at the "bottom >> of the hierarchy" (southernmost). >> >> s/fully configure/fully determine/ >> >> Reasonable=EF=BC=8Caccepted. > >> >> >> ... So the ToF nodes can exchange the full list of >> prefixes that exist in the fabric and figure when a ToF node lacks >> reachability and to existing prefix. >> >> >> Is an "out" needed after "figure", and should "and to existing prefix" b= e "to some prefixes"? >> >> Right=EF=BC=8Caccepted. > >> >> >> ... In the case of Negative Disaggregation, the last ToF >> node(s) that injects the route may also incur an incast issue; this >> problem would occur if a prefix that becomes totally unreachable is >> disaggregated, but doing so is mostly useless and is not recommended. >> >> What does "so" refer to, in the last sentence above? >> >> since this paragraph is talking about =E2=80=9Cnote=E2=80= =9D, I would >> like to delete the last sentence. > >> >> >> It is not envisioned in the short term that the average fabric >> supports a Precision Time Protocol [IEEEstd1588], and the precision >> that may be available with the Network Time Protocol [RFC5905], in >> the order of 100 to 200ms, may not be necessarily enough to cover, >> e.g., the fast mobility of a Virtual Machine. >> >> I struggled with the above paragraph. Perhaps reword to the following? >> >> Reasonable=EF=BC=8Caccepted. > >> >> >> It is not envisioned that an average fabric supports Precision Time P= rotocol >> [IEEEstd1588] in the short term, nor that the precision available wit= h >> the Network Time Protocol [RFC5905] (in the order of 100 to 200ms) >> >> may not be necessarily enough to cover, e.g., the fast mobility of a = Virtual Machine. >> >> Maybe even change the double negative. >> >> RIFT doesn't precondition that nodes of the fabric have reachable >> addresses. But the operational purposes to reach the internal nodes >> may exist. >> >> s/purposes/reasons/? >> >> OK=EF=BC=8Caccepted. > >> >> >> In a fully connected ToF, in case of failure between ToF2 and spine >> nodes, ToF2's loopback address must be disaggregated recursively all >> the way to the leaves. >> >> In a partitioned ToF, a TOF node is only reachable within its Plane, >> and the disaggregation to the leaves is also required. A possible >> alternative is to use the ring that interconnects the ToF nodes to >> transmit packets between them for their loopback addresses only... >> >> >> If I understand it correctly, the above two paragraphs should be as foll= owing (the ring alternative to recursive disaggregation applies to both ful= ly connected ToF and partitioned ToF): >> >> Better=EF=BC=8Caccepted. > >> >> >> In case of failure between ToF2 and spine >> nodes, ToF2's loopback address must be disaggregated recursively all >> >> the way to the leaves. In a partitioned ToF, even with recursive disa= ggregation >> a ToF node is only reachable within its plane. >> >> A possible alternative to recursive disaggregation is to use a ring >> that interconnects the ToF nodes to >> transmit packets between them for their loopback addresses only... >> >> For the following: >> >> If a controller is attaching to the RIFT domain from ToF, it usually >> uses dual-homing connections. The loopback prefix of the controller >> should be advertised down by the ToF and spine to leaves. If the >> controller loses link to ToF, make sure the ToF withdraw the prefix >> of the controller(use different mechanisms). >> >> What does "(use different mechanisms)" mean? >> >> the interworking between controller and ToF is outside of >> RIFT domain. so ToF withdraw the prefix of the controller will use >> different mechanisms other than RIFT > >> >> 5.12. Internet Connectivity With Underlay >> >> s/With/Within/? >> >> Better=EF=BC=8Caccepted. > >> >> >> In case that an internet access request comes from a leaf and the >> internet gateway is another leaf ... >> >> >> Where else could the internet access request come from? With the request= from a non-leaf, don't you also need the default route to be advertised by= the internet gateway? >> >> "5.12.2. Internet Default on the ToFs" is the other case. >> > >> > > yeah, it's complex, people will get confused. you have to stop to > advertise in RIFT a default but use a "fabric-default" or have preference > rules. > >> >> >> If the traffic comes from ToF to Leaf111 or Leaf121 which has anycast >> prefix PrefixA. RIFT can deal with this case well. >> >> s/. RIFT/, RIFT/ >> >> OK=EF=BC=8Caccepted. > >> >> >> The adds huge >> capabilities for leaf-2-leaf ECMP paths, but additional complexity >> with the need to disaggregate. Also RIFT uses Link State flooding >> northwards, and is not designed for low-power operation. >> >> s/The/This/ >> >> OK=EF=BC=8Caccepted. > >> >> Why is low-poer operation mentioned all? It's not like that we'll run RI= FT on IOTs? The following only talks about IOT being attached to leaves: >> >> You are right, But I think the first two paragraphs of >> this section is talking about RIFT design principles and applicability i= n >> general. The third paragraph starts to talk >> about IOT being attached to leaves> >> >> Still nothing prevents that the IP devices connected at the Leaf are >> IoT (Internet of Things) devices, which typically expose their >> address using WiND - which is an upgrade from 6LoWPAN ND [RFC6775]. >> >> And are the following specific to IOT? >> >> The following is not specific to IoT, but it doesn't >> violate the topic of this section?> >> >> A network that serves high speed/ high power IoT devices should >> typically provide deterministic capabilities for applications such as >> high speed control loops or movement detection. The Fat Tree is >> highly reliable, and in normal condition provides an equilatent >> multipath operation; but the ECMP doesn't provide hard guarantees for >> either delivery or latency. As long as the fabric is non-blocking >> the result is the same; but there can be load unbalances resulting in >> incast and possibly congestion loss that will prevent the delivery >> within bounded latency. >> >> This could be alleviated with Packet Replication, Elimination and >> Reordering (PREOF) [RFC8655] leaf-2-leaf but PREOF is hard to provide >> at the scale of all flows, and the replication may increase the >> probability of the overload that it attempts to solve. >> >> Thanks! >> Jeffrey >> _______________________________________________ >> RIFT mailing list >> RIFT@ietf.org >> https://www.ietf.org/mailman/listinfo/rift >> >> >> _______________________________________________ >> RIFT mailing list >> RIFT@ietf.org >> https://www.ietf.org/mailman/listinfo/rift >> > > --0000000000005344c905ceec0890 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


=
On Fri, Oct 22, 2021 at 3:42 AM <<= a href=3D"mailto:wei.yuehua@zte.com.cn">wei.yuehua@zte.com.cn> wrote= :

Dear Toni, Jeffrey, and RIFTers,

Follow= up comment resolutions:


They=C2=A0tend=C2=A0to=C2=A0need=C2=A0extensive=C2=A0= configuration=C2=A0or=C2=A0provisioning=C2=A0during
=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0bring=C2=A0up=C2=A0and=C2=A0re-dimensioning.

<YuehuaWei5> so=EF=BC=8C= will replace =E2=80=9Cre-dimensioning=E2=80=9Dto "scaling"?><= /span>


somehthing like this or ju= st say "adding or removing switching elements from the fabric"=C2= =A0


=C2=A0 =C2=A0*=C2=A0=C2=A0Can=C2=A0= utilize=C2=A0all=C2=A0paths=C2=A0through=C2=A0fabric=C2=A0without=C2=A0loop= ing
=C2=A0=C2=A0=C2=A0...
=C2=A0=C2=A0=C2=A0*=C2=A0=C2=A0Supports=C2=A0non-equal=C2=A0= cost=C2=A0multipath=C2=A0...

Aren't=C2=A0the=C2=A0above=C2=A0two=C2=A0the=C2=A0sa= me/related?

<YuehuaWei7> keep=C2=A0 "*=C2=A0=C2=A0Can=C2=A0uti= lize=C2=A0all=C2=A0paths=C2=A0through=C2=A0fabric=C2=A0without=C2=A0looping= ", remove "=C2=A0*=C2=A0=C2=A0Supports=C2=A0non-equal=C2=A0cost= =C2=A0multipath=C2=A0..."


=
as I wrote "all paths without looping". take any variation y= ou like that says that
=C2=A0


The=C2=A0"but"=C2=A0wording=C2=A0in=C2=A0the=C2=A0following=C2= =A0is=C2=A0a=C2=A0bit=C2=A0strange:

=C2=A0=C2=A0=C2=A0...=C2=A0it=C2=A0is
=C2=A0=C2=A0=C2=A0recommended=C2=A0to=C2=A0configure= =C2=A0the=C2=A0level=C2=A0of=C2=A0all=C2=A0the=C2=A0nodes=C2=A0but=C2=A0tho= se=C2=A0that
=C2=A0=C2=A0=C2=A0are=C2=A0for= ced=C2=A0as=C2=A0leaves=C2=A0to=C2=A0avoid=C2=A0an=C2=A0undesirable=C2=A0in= teraction=C2=A0between=C2=A0ZTP
=C2=A0=C2= =A0=C2=A0and=C2=A0the=C2=A0manual=C2=A0configuration.

Do=C2=A0you=C2=A0mean=C2=A0&quo= t;those=C2=A0that=C2=A0are=C2=A0forced=C2=A0as=C2=A0leaves"=C2=A0do=C2= =A0not=C2=A0need=C2=A0configuration?=C2=A0But=C2=A0then=C2=A0how=C2=A0are= =C2=A0they=C2=A0"forced=C2=A0as=C2=A0leaves"=C2=A0w/o=C2=A0config= uration?

=C2=A0<YuehuaWei20>=C2=A0= will delete "=C2=A0but=C2=A0those=C2=A0that=C2=A0=C2=A0are=C2=A0force= d=C2=A0as=C2=A0leaves=C2=A0". >

<= br>

it should read more "forced as leaves to = avoid formation of undesirable topologies"
=C2=A0
=



Be= st Regards,

<= span style=3D"font-family:Arial;color:rgb(51,51,51);font-size:14px">=C2=A0<= /span>

Yuehua Wei

M= :=C2=A0+86 13851460269=C2=A0E:=C2=A0<= /span>wei.y= uehua@zte.com.cn


=E5=8E=9F=E5=A7=8B=E9=82=AE=E4=BB=B6
=E5=8F=91=E4= =BB=B6=E4=BA=BA=EF=BC=9ATonyPrzygienda
=
=E6=94=B6=E4=BB=B6=E4=BA=BA=EF=BC=9A=E9=AD=8F=E6=9C=88=E5=8D=8E00019655;
=E6=8A=84=E9= =80=81=E4=BA=BA=EF=BC=9AJeffrey (Zhaohui= ) Zhang;Antoni Przygien= da;rift@ietf.org;
=E6=97=A5 =E6=9C=9F =EF=BC=9A2021=E5=B9=B410=E6=9C=8821= =E6=97=A5 23:35
=E4=B8=BB =E9=A2=98 =EF=BC=9A= Re: [Rift] Shepherd review of draft-ietf-rift-applicability
inline

On Thu, Oct 21, 2021 at= 10:07 AM <we= i.yuehua@zte.com.cn> wrote:

Dear Jeffrey and Toni,

Please se= e my comments resolution in line start with "<YuehuaWei".

<= p>Would like Toni to look at=C2=A0<YuehuaWei5>,=C2=A0<YuehuaWei6&g= t; as well.

Thank you!


Best Regards,

Yuehua Wei

ZTE Corporation

= M:=C2=A0+86 1385= 1460269=C2=A0E:=C2=A0wei.yuehua@zte.com.cn
<= /p>


=E5=8F=91=E4=BB= =B6=E4=BA=BA=EF=BC=9AJeffrey(Zhaohui)Zhang
=E6=94=B6=E4=BB= =B6=E4=BA=BA=EF=BC=9Adraft-ietf-rift-ap= plicability@ietf.org;
=E6=8A=84=E9=80=81=E4=BA=BA= =EF=BC=9A'rift@ietf.org';
=E6=97= =A5 =E6=9C=9F =EF=BC=9A2021=E5=B9=B409=E6=9C=8825=E6=97=A5 09:02
<= div>=E4=B8=BB =E9=A2=98 =EF=BC=9A[Rift] Shepherd review of draft-= ietf-rift-applicability
Hi,

As=C2=A0part=C2=A0o= f=C2=A0the=C2=A0shepherd=C2=A0review,=C2=A0I=C2=A0have=C2=A0the=C2=A0follow= ing=C2=A0questions/comments.=C2=A0Some=C2=A0are=C2=A0minor=C2=A0editorial= =C2=A0nits.

=C2=A0=C2=A0=C2=A0Node=C2=A0TIE=C2=A0should=C2=A0NOT=C2= =A0be=C2=A0confused=C2=A0with=C2=A0a=C2=A0North
=C2=A0=C2=A0=C2=A0TIE=C2= =A0since=C2=A0"node"=C2=A0defines=C2=A0the=C2=A0type=C2=A0of=C2= =A0TIE=C2=A0rather=C2=A0than=C2=A0its=C2=A0direction.

Should=C2=A0t= his=C2=A0be=C2=A0the=C2=A0following?

=C2=A0=C2=A0=C2=A0N-TIE=C2=A0s= hould=C2=A0not=C2=A0be=C2=A0confused=C2=A0with=C2=A0a=C2=A0Node=C2=A0TIE=C2= =A0-=C2=A0the=C2=A0"N-"=C2=A0denotes
=C2=A0=C2=A0=C2=A0"N= orth-"=C2=A0not=C2=A0"Node-".

<YuehuaWei0>Yes>


For=C2=A0the=C2= =A0following:

=C2=A0=C2=A0=C2=A0This=C2=A0is=C2=A0an=C2=A0acronym= =C2=A0for=C2=A0a=C2=A0"Prefix=C2=A0Topology=C2=A0Information=C2=A0Elem= ent"=C2=A0and=C2=A0it
=C2=A0=C2=A0=C2=A0contains=C2=A0all=C2=A0pref= ixes=C2=A0directly=C2=A0attached=C2=A0to=C2=A0this=C2=A0node=C2=A0in=C2=A0c= ase=C2=A0of=C2=A0a
=C2=A0=C2=A0=C2=A0North=C2=A0TIE=C2=A0and=C2=A0in=C2= =A0case=C2=A0of=C2=A0South=C2=A0TIE=C2=A0the=C2=A0necessary=C2=A0default=C2= =A0routes=C2=A0the
=C2=A0=C2=A0=C2=A0node=C2=A0advertises=C2=A0southboun= d.

Should=C2=A0"default=C2=A0routes"=C2=A0be=C2=A0&quo= t;default=C2=A0and=C2=A0disaggregated=C2=A0routes"?

<YuehuaWei1>the discription of this acronym i= s copied from rift-rift, shall I keep it the same with rift-rift?=C2=A0>


=C2=A0=C2=A0=C2=A0= ...=C2=A0RIFT=C2=A0can=C2=A0employ=C2=A0to=C2=A0ultimately
=C2=A0=C2=A0= =C2=A0calculate=C2=A0routes=C2=A0of=C2=A0which=C2=A0Dijkstra=C2=A0algorithm= =C2=A0is=C2=A0a=C2=A0possible=C2=A0one.

The=C2=A0above=C2=A0does=C2= =A0not=C2=A0read=C2=A0well=C2=A0to=C2=A0me.=C2=A0Is=C2=A0some=C2=A0wording= =C2=A0missing?

<YuehuaWei2> the discription of this acronym is also copie= d from rift-rift, shall I keep it the same with rift-rift?=C2=A0>


=C2=A0=C2=A0=C2=A0Clos=C2=A0[CLOS]=C2=A0topologies=C2=A0(c= alled=C2=A0commonly=C2=A0a=C2=A0fat=C2=A0tree/network=C2=A0in=C2=A0modern=C2=A0=C2=A0=C2=A0IP=C2=A0fabric=C2=A0considerations=C2=A0as=C2=A0homonym= =C2=A0to=C2=A0the=C2=A0original=C2=A0definition=C2=A0of=C2=A0the
=C2=A0= =C2=A0=C2=A0term=C2=A0Fat=C2=A0Tree=C2=A0[FATTREE])have=C2=A0gained=C2=A0pr= ominence=C2=A0in=C2=A0today's=C2=A0networking,

Missing=C2=A0a= =C2=A0"=C2=A0"=C2=A0in=C2=A0the=C2=A0last=C2=A0line.

<YuehuaWei3> Accepted >


=C2=A0=C2=A0=C2=A0c=C2=A0protocols=C2=A0were=C2=A0geared=C2=A0towa= rds=C2=A0a=C2=A0network=C2=A0with
=C2=A0=C2=A0=C2=A0an=C2=A0irregular=C2= =A0topology=C2=A0with=C2=A0isotropic=C2=A0properties,=C2=A0and=C2=A0low=C2= =A0degree=C2=A0of
=C2=A0=C2=A0=C2=A0connectivity.

"Today= 9;s=C2=A0current=C2=A0...=C2=A0were"=C2=A0sounds=C2=A0strange.=C2=A0Ho= w=C2=A0about=C2=A0"Other=C2=A0routing=C2=A0protocols=C2=A0are"?

<YuehuaWei4>How about "= The current routing protocols are......." ?>


= =C2=A0=C2=A0=C2=A0*=C2=A0=C2=A0They=C2=A0tend=C2=A0to=C2=A0need=C2=A0extens= ive=C2=A0configuration=C2=A0or=C2=A0provisioning=C2=A0during
=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0bring=C2=A0up=C2=A0and=C2=A0re-dimensioning.
=
"re-dimensioning"=C2=A0lacks=C2=A0context.=C2=A0What=C2=A0do= es=C2=A0it=C2=A0mean?=C2=A0"reconfiguration"?

<YuehuaWei5> it comes from Toni's present= ation.=C2=A0 I think it means "scaling", Would like to call Toni = for comfirmation=EF=BC=8Cthanks=C2=A0>


well, when you add or remove switches/PoD etc
=C2=A0=


=C2=A0=C2=A0=C2= =A0The=C2=A0N-TIEs=C2=A0contain=C2=A0a=C2=A0link-state=C2=A0topology=C2=A0d= escription=C2=A0of=C2=A0lower=C2=A0levels
=C2=A0=C2=A0=C2=A0and=C2=A0S-T= IEs=C2=A0carry=C2=A0simply=C2=A0default=C2=A0routes=C2=A0for=C2=A0the=C2=A0= lower=C2=A0levels.

"default=C2=A0and=C2=A0disaggregated=C2=A0r= outes"?

<YuehuaWei5> t= he same as YuehuaWei1>

=

correct
=C2=A0


=C2=A0=C2=A0=C2=A0RIFT=C2= =A0also=C2=A0eliminates=C2=A0major=C2=A0disadvantages=C2=A0of=C2=A0link-sta= te=C2=A0and=C2=A0distance-
=C2=A0=C2=A0=C2=A0vector=C2=A0with:
=C2=A0= =C2=A0=C2=A0*=C2=A0=C2=A0Reduced=C2=A0and=C2=A0balanced=C2=A0flooding
= =C2=A0=C2=A0=C2=A0*=C2=A0=C2=A0Automatic=C2=A0neighbor=C2=A0detection
<= br>Does=C2=A0link-state=C2=A0routing=C2=A0not=C2=A0have=C2=A0auto=C2=A0neig= hbor=C2=A0detection?

<YuehuaWe= i6>=C2=A0 How about=C2=A0 changing to=E2=80=9CLevel constrained automati= c=C2=A0neighbor=C2=A0detection=E2=80=9D=EF=BC=9F=C2=A0Would like to ask for Toni's comments=C2=A0= >

<= /div>

agreed
=C2=A0


=C2=A0=C2=A0=C2=A0*=C2=A0=C2=A0Can=C2=A0utilize=C2=A0all=C2=A0paths= =C2=A0through=C2=A0fabric=C2=A0without=C2=A0looping
=C2=A0=C2=A0=C2=A0..= .
=C2=A0=C2=A0=C2=A0*=C2=A0=C2=A0Supports=C2=A0non-equal=C2=A0cost=C2=A0= multipath=C2=A0...

Aren't=C2=A0the=C2=A0above=C2=A0two=C2=A0the= =C2=A0same/related?

<YuehuaWei= 7>=C2=A0 I think the two above are nearly the same . Since "loop fr= ee" has been stated in other part of the document. I would like to del= ete "Can=C2=A0utilize=C2=A0all=C2=A0paths=C2=A0through=C2=A0fabric=C2= =A0without=C2=A0looping">=

yes, in a sense it's the same, I would just stick to "utiliz= e all paths in loop-free fashion"
=C2=A0


4.2.1.=C2=A0=C2=A0Horizontal=C2=A0Li= nks

=C2=A0=C2=A0=C2=A0RIFT=C2=A0is=C2=A0not=C2=A0limited=C2=A0to=C2= =A0pure=C2=A0Clos=C2=A0divided=C2=A0into=C2=A0PoD=C2=A0and=C2=A0multi-plane= s
=C2=A0=C2=A0=C2=A0but=C2=A0supports=C2=A0horizontal=C2=A0(East-West)= =C2=A0links=C2=A0below=C2=A0the=C2=A0top=C2=A0of=C2=A0fabric
=C2=A0=C2= =A0=C2=A0level.=C2=A0=C2=A0Those=C2=A0links=C2=A0are=C2=A0used=C2=A0only=C2= =A0for=C2=A0last=C2=A0resort=C2=A0northbound=C2=A0routes
=C2=A0=C2=A0=C2= =A0when=C2=A0a=C2=A0spine=C2=A0loses=C2=A0all=C2=A0its=C2=A0northbound=C2= =A0links=C2=A0or=C2=A0cannot=C2=A0compute=C2=A0a
=C2=A0=C2=A0=C2=A0defau= lt=C2=A0route=C2=A0through=C2=A0them.

=C2=A0=C2=A0=C2=A0A=C2=A0poss= ible=C2=A0configuration=C2=A0is=C2=A0a=C2=A0"ring"=C2=A0of=C2=A0h= orizontal=C2=A0links=C2=A0at=C2=A0a=C2=A0level.
=C2=A0=C2=A0=C2=A0In=C2= =A0presence=C2=A0of=C2=A0such=C2=A0a=C2=A0"ring"=C2=A0in=C2=A0any= =C2=A0level=C2=A0(except=C2=A0Top=C2=A0of=C2=A0Fabric=C2=A0(ToF)
=C2=A0= =C2=A0=C2=A0level)=C2=A0neither=C2=A0North=C2=A0SPF=C2=A0(N-SPF)=C2=A0nor= =C2=A0South=C2=A0SPF=C2=A0(S-SPF)=C2=A0will=C2=A0provide=C2=A0a
=C2=A0= =C2=A0=C2=A0"ring-based=C2=A0protection"=C2=A0scheme=C2=A0since= =C2=A0such=C2=A0a=C2=A0computation=C2=A0would=C2=A0have=C2=A0to
=C2=A0= =C2=A0=C2=A0deal=C2=A0necessarily=C2=A0with=C2=A0breaking=C2=A0of=C2=A0&quo= t;loops"=C2=A0in=C2=A0Dijkstra=C2=A0sense;=C2=A0an
=C2=A0=C2=A0=C2= =A0application=C2=A0for=C2=A0which=C2=A0RIFT=C2=A0is=C2=A0not=C2=A0intended= .

=C2=A0=C2=A0=C2=A0A=C2=A0full-mesh=C2=A0connectivity=C2=A0between= =C2=A0nodes=C2=A0on=C2=A0the=C2=A0same=C2=A0level=C2=A0can=C2=A0be
=C2= =A0=C2=A0=C2=A0employed=C2=A0and=C2=A0that=C2=A0allows=C2=A0N-SPF=C2=A0to= =C2=A0provide=C2=A0for=C2=A0any=C2=A0node=C2=A0loosing=C2=A0all
=C2=A0= =C2=A0=C2=A0its=C2=A0northbound=C2=A0adjacencies=C2=A0(as=C2=A0long=C2=A0as= =C2=A0any=C2=A0of=C2=A0the=C2=A0other=C2=A0nodes=C2=A0in=C2=A0the
=C2=A0= =C2=A0=C2=A0level=C2=A0are=C2=A0northbound=C2=A0connected)=C2=A0to=C2=A0sti= ll=C2=A0participate=C2=A0in=C2=A0northbound
=C2=A0=C2=A0=C2=A0forwarding= .

I=C2=A0struggled=C2=A0a=C2=A0bit=C2=A0with=C2=A0the=C2=A0second= =C2=A0paragraph=C2=A0above.=C2=A0Is=C2=A0the=C2=A0following=C2=A0understand= ing=C2=A0of=C2=A0all=C2=A0three=C2=A0paragraphs=C2=A0correct?

1.=C2= =A0east-west=C2=A0links=C2=A0below=C2=A0TOF=C2=A0provide=C2=A0last=C2=A0res= ort=C2=A0northbound=C2=A0routes=C2=A0(1st=C2=A0paragraph)=C2=A0-=C2=A0BTW= =C2=A0should=C2=A0it=C2=A0be=C2=A0"northbound=C2=A0forwarding"=C2= =A0instead=C2=A0of=C2=A0"northbound=C2=A0route"?
2.=C2=A0a=C2= =A0full=C2=A0mesh=C2=A0east-west=C2=A0links=C2=A0between=C2=A0nodes=C2=A0at= =C2=A0the=C2=A0same=C2=A0level=C2=A0provides=C2=A0last=C2=A0resort=C2=A0nor= thbound=C2=A0forwarding=C2=A0for=C2=A0all=C2=A0the=C2=A0nodes=C2=A0(3rd=C2= =A0paragraph)=C2=A0(extending=C2=A0on=C2=A0#1)
3.=C2=A0however,=C2=A0a= =C2=A0ring=C2=A0of=C2=A0horizontal=C2=A0links=C2=A0does=C2=A0not=C2=A0provi= de=C2=A0ring-based=C2=A0protection=C2=A0(2nd=C2=A0paragraph)

If=C2= =A0so,=C2=A0it=C2=A0may=C2=A0be=C2=A0better=C2=A0to=C2=A0move=C2=A0the=C2= =A03rd=C2=A0paragraph=C2=A0up,=C2=A0and=C2=A0change=C2=A0the=C2=A0previous= =C2=A02nd=C2=A0paragraph=C2=A0to=C2=A0the=C2=A0following:

=C2=A0=C2= =A0=C2=A0Note=C2=A0that=C2=A0a=C2=A0"ring"=C2=A0of=C2=A0horizonta= l=C2=A0links=C2=A0at=C2=A0any=C2=A0level=C2=A0below=C2=A0ToF=C2=A0does
= =C2=A0=C2=A0=C2=A0not=C2=A0provide=C2=A0a=C2=A0"ring-based=C2=A0protec= tion"=C2=A0scheme=C2=A0since=C2=A0the=C2=A0SPF=C2=A0computation
=C2= =A0=C2=A0=C2=A0would=C2=A0have=C2=A0to=C2=A0deal=C2=A0necessarily=C2=A0with= =C2=A0breaking=C2=A0of=C2=A0"loops"=C2=A0in=C2=A0Dijkstra=C2=A0se= nse=C2=A0-=C2=A0an
=C2=A0=C2=A0=C2=A0application=C2=A0for=C2=A0which=C2= =A0RIFT=C2=A0is=C2=A0not=C2=A0intended.

<YuehuaWei8>=C2=A0 reasonable,=C2=A0 Accepted.=C2=A0 will repl= ace "northbound=C2=A0forwarding"=C2=A0with "northbound=C2=A0= route", and switch 2nd paragraph and 3rd paragraph.>


in fact s= uch forwarding can be implemented but accepted, we don't want to go dow= n that route ;-)
=C2=A0


In=C2=A0the=C2=A0following:

=C2=A0=C2=A0=C2=A0*= =C2=A0=C2=A0Southbound,=C2=A0RIFT=C2=A0operates=C2=A0as=C2=A0a=C2=A0distanc= e-vector=C2=A0protocol,=C2=A0whereby
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0the=C2=A0control=C2=A0packets=C2=A0are=C2=A0flooded=C2=A0only=C2=A0one-h= op,=C2=A0interpreted,=C2=A0and=C2=A0the
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0consequence=C2=A0of=C2=A0that=C2=A0computation=C2=A0is=C2=A0what=C2= =A0gets=C2=A0flooded=C2=A0one=C2=A0more=C2=A0hop
=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0south.=C2=A0=C2=A0In=C2=A0the=C2=A0most=C2=A0common=C2=A0use= -cases,=C2=A0a=C2=A0ToF=C2=A0node=C2=A0can=C2=A0reach=C2=A0most=C2=A0of
= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0the=C2=A0prefixes=C2=A0in=C2=A0the=C2= =A0fabric.=C2=A0=C2=A0If=C2=A0that=C2=A0is=C2=A0the=C2=A0case,=C2=A0the=C2= =A0ToF=C2=A0node
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0advertises=C2=A0the= =C2=A0fabric=C2=A0default=C2=A0and=C2=A0disaggregates=C2=A0the=C2=A0prefixe= s=C2=A0that
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0it=C2=A0cannot=C2=A0reac= h.

Perhaps=C2=A0changing=C2=A0"consequence"=C2=A0to=C2= =A0"result"?

<YuehuaW= ei9> Reasonable=EF=BC=8Caccepted>

In=C2=A0the=C2=A0last=C2=A0sentence,=C2=A0perhaps=C2=A0= say=C2=A0"negatively=C2=A0disaggregates"=C2=A0(if=C2=A0I=C2=A0und= erstand=C2=A0it=C2=A0correctly)?=C2=A0&l= t;YuehuaWei10> Reasonable=EF=BC=8Caccepted >


=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0In=C2=A0the=C2=A0general=C2=A0case,=C2=A0what=C2= =A0gets=C2=A0advertised=C2=A0south=C2=A0is=C2=A0in=C2=A0more
=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0details:

Perhaps=C2=A0change=C2=A0to= =C2=A0"...=C2=A0what=C2=A0get=C2=A0advertised=C2=A0south=C2=A0are:&quo= t;?=C2=A0(remove=C2=A0the=C2=A0"in=C2=A0more=C2=A0details")

=C2=A0<YuehuaWei11> Reasonable=EF= =BC=8Caccepted >


4.2.3.=C2=A0=C2=A0Generalizing=C2=A0to=C2= =A0any=C2=A0Directed=C2=A0Acyclic=C2=A0Graph

=C2=A0=C2=A0=C2=A0RIFT= =C2=A0is=C2=A0an=C2=A0anisotropic=C2=A0routing=C2=A0protocol,=C2=A0meaning= =C2=A0that=C2=A0it=C2=A0has=C2=A0a=C2=A0sense
=C2=A0=C2=A0=C2=A0of=C2=A0= direction=C2=A0(northbound,=C2=A0southbound,=C2=A0east-west)=C2=A0and=C2=A0= that=C2=A0it=C2=A0operates
=C2=A0=C2=A0=C2=A0differently=C2=A0depending= =C2=A0on=C2=A0the=C2=A0direction.
=C2=A0=C2=A0=C2=A0...
=C2=A0=C2=A0= =C2=A0A=C2=A0Directed=C2=A0Acyclic=C2=A0Graph=C2=A0(DAG)=C2=A0provides=C2= =A0a=C2=A0sense=C2=A0of=C2=A0north=C2=A0(the
=C2=A0=C2=A0=C2=A0direction= =C2=A0of=C2=A0the=C2=A0DAG)=C2=A0and=C2=A0of=C2=A0south=C2=A0(the=C2=A0reve= rse),=C2=A0which=C2=A0can=C2=A0be=C2=A0used
=C2=A0=C2=A0=C2=A0to=C2=A0ap= ply=C2=A0RIFT.=C2=A0=C2=A0For=C2=A0the=C2=A0purpose=C2=A0of=C2=A0RIFT,=C2= =A0an=C2=A0edge=C2=A0in=C2=A0the=C2=A0DAG=C2=A0that=C2=A0has
=C2=A0=C2= =A0=C2=A0only=C2=A0incoming=C2=A0vertices=C2=A0is=C2=A0a=C2=A0ToF=C2=A0node= .

I=C2=A0initially=C2=A0struggled=C2=A0a=C2=A0bit=C2=A0with=C2=A0th= e=C2=A0second=C2=A0paragraph=C2=A0above.=C2=A0Connecting=C2=A0to=C2=A0the= =C2=A0section=C2=A0title,=C2=A0perhaps=C2=A0the=C2=A0following=C2=A0wording= =C2=A0is=C2=A0better:

=C2=A0=C2=A0=C2=A0Since=C2=A0a=C2=A0Directed= =C2=A0Acyclic=C2=A0Graph=C2=A0(DAG)=C2=A0provides=C2=A0a=C2=A0sense=C2=A0of= =C2=A0north=C2=A0(the
=C2=A0=C2=A0=C2=A0direction=C2=A0of=C2=A0the=C2=A0= DAG)=C2=A0and=C2=A0of=C2=A0south=C2=A0(the=C2=A0reverse),=C2=A0it=C2=A0can= =C2=A0be=C2=A0used=C2=A0to
=C2=A0=C2=A0=C2=A0apply=C2=A0RIFT=C2=A0=E2=80=94=C2=A0an=C2=A0edge=C2=A0in=C2=A0the=C2=A0DAG=C2=A0t= hat=C2=A0has=C2=A0only=C2=A0incoming=C2=A0vertices=C2=A0is=C2=A0a
=C2=A0= =C2=A0=C2=A0ToF=C2=A0node.

=C2=A0= <YuehuaWei12> Reasonable=EF=BC=8Caccepted.=C2=A0 will change the En dash (=E2=80=93) to=C2=A0Em dash(= =E2=80=94)>

In=C2= =A0the=C2=A0following:


=C2=A0=C2=A0=C2=A0RIFT=C2=A0is=C2=A0not=C2=A0= strictly=C2=A0limited=C2=A0to=C2=A0Clos=C2=A0topologies.=C2=A0=C2=A0The=C2= =A0protocol=C2=A0only
=C2=A0=C2=A0=C2=A0requires=C2=A0a=C2=A0sense=C2=A0= of=C2=A0"compass=C2=A0rose=C2=A0directionality"=C2=A0either=C2=A0= achieved
=C2=A0=C2=A0=C2=A0through=C2=A0configuration=C2=A0or=C2=A0deriv= ation=C2=A0of=C2=A0levels.=C2=A0=C2=A0So,=C2=A0conceptually,
=C2=A0=C2= =A0=C2=A0shortcuts=C2=A0between=C2=A0levels=C2=A0could=C2=A0be=C2=A0include= d.=C2=A0=C2=A0Figure=C2=A02=C2=A0depicts=C2=A0an
=C2=A0=C2=A0=C2=A0examp= le=C2=A0of=C2=A0a=C2=A0shortcut=C2=A0between=C2=A0levels.=C2=A0=C2=A0In=C2= =A0this=C2=A0example,=C2=A0sub-optimal
=C2=A0=C2=A0=C2=A0routing=C2=A0wi= ll=C2=A0occur=C2=A0when=C2=A0traffic=C2=A0is=C2=A0sent=C2=A0from=C2=A0L0=C2= =A0to=C2=A0L1=C2=A0via=C2=A0S0's
=C2=A0=C2=A0=C2=A0default=C2=A0rout= e=C2=A0and=C2=A0back=C2=A0down=C2=A0through=C2=A0A0=C2=A0or=C2=A0A1.=C2=A0= =C2=A0In=C2=A0order=C2=A0to=C2=A0ensure
=C2=A0=C2=A0=C2=A0that,=C2=A0onl= y=C2=A0default=C2=A0routes=C2=A0from=C2=A0A0=C2=A0or=C2=A0A1=C2=A0are=C2=A0= used,=C2=A0all=C2=A0leaves=C2=A0would=C2=A0be
=C2=A0=C2=A0=C2=A0required= =C2=A0to=C2=A0install=C2=A0each=C2=A0others=C2=A0routes.

Should=C2= =A0"ensure"=C2=A0be=C2=A0"avoid"?

=C2=A0<YuehuaWei13> Right=EF=BC=8Caccepted.=C2=A0 >

=C2=A0=C2=A0=C2=A0Commercial=C2=A0edifices=C2= =A0are=C2=A0often=C2=A0cabled=C2=A0in=C2=A0topologies=C2=A0that=C2=A0are=C2= =A0either

=C2=A0=C2=A0=C2=A0Clos=C2=A0or=C2=A0its=C2=A0isomorphic=C2=A0e= quivalents.=C2=A0=C2=A0The=C2=A0Clos=C2=A0can=C2=A0grow=C2=A0rather=C2=A0hi= gh
=C2=A0=C2=A0=C2=A0with=C2=A0many=C2=A0floors.

If=C2=A0I=C2=A0= understand=C2=A0it=C2=A0correctly,=C2=A0better=C2=A0change=C2=A0"floor= s"=C2=A0to=C2=A0"levels".=C2=A0We're=C2=A0talking=C2=A0a= bout=C2=A0commercial=C2=A0buildings=C2=A0here,=C2=A0so=C2=A0"floor&quo= t;=C2=A0may=C2=A0be=C2=A0confused=C2=A0as=C2=A0"building=C2=A0floors&q= uot;,=C2=A0which=C2=A0I=C2=A0don't=C2=A0think=C2=A0it=C2=A0is=C2=A0refe= rring=C2=A0to.

=C2=A0<YuehuaWe= i14> Reasonable=EF=BC=8Caccepted.=C2=A0>

=C2=A0= =C2=A0=C2=A0RIFT=C2=A0is=C2=A0neither=C2=A0IP=C2=A0specific=C2=A0and=C2=A0h= ence=C2=A0any=C2=A0link=C2=A0addressing

=C2=A0=C2=A0=C2=A0connecting=C2= =A0internal=C2=A0device=C2=A0subnets=C2=A0is=C2=A0conceivable.

s/ne= ither/not/

=C2=A0<YuehuaWei15&= gt; Right=EF=BC=8Caccepted.=C2=A0= =C2=A0>

=C2=A0=C2= =A0=C2=A0*=C2=A0=C2=A0RIFT=C2=A0negotiates=C2=A0automatically=C2=A0BFD=C2= =A0per=C2=A0link=C2=A0allowing=C2=A0this=C2=A0way=C2=A0for

=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0IP=C2=A0and=C2=A0micro-BFD=C2=A0[RFC7130]=C2=A0to= =C2=A0replace=C2=A0Link=C2=A0Aggregation=C2=A0Groups
=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0(LAGs)=C2=A0which=C2=A0do=C2=A0hide=C2=A0bandwidth=C2=A0i= mbalances=C2=A0in=C2=A0case=C2=A0of=C2=A0constituent

=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0failures.


I=C2=A0find=C2=A0it=C2=A0a= =C2=A0bit=C2=A0hard=C2=A0to=C2=A0parse=C2=A0the=C2=A0above.=C2=A0Perhaps=C2= =A0break=C2=A0it=C2=A0down=C2=A0a=C2=A0bit?

=C2=A0<YuehuaWei16> Would like= to change to the following wording:

=C2=A0 =C2=A0 =C2=A0 RIFT MAY incorp= orate BFD [RFC5881] to react quickly to link failures. After RIFT ThreeWay = hello adjacency convergence a BFD session MAY

=C2=A0 =C2=A0 =C2=A0 be for= med automatically between the RIFT endpoints without further

=C2=A0 =C2= =A0 =C2=A0 configuration using the exchanged discriminators.=C2=A0>


=C2=A0=C2=A0=C2=A0Without=C2=A0disaggregation=C2=A0mechanism,=C2= =A0when=C2=A0linkSL6=C2=A0fails,=C2=A0the=C2=A0packet=C2=A0from
=C2=A0= =C2=A0=C2=A0leaf121=C2=A0to=C2=A0prefix122=C2=A0will=C2=A0probably=C2=A0go= =C2=A0up=C2=A0through=C2=A0linkSL5=C2=A0to=C2=A0linkTS3
=C2=A0=C2=A0=C2= =A0then=C2=A0go=C2=A0down=C2=A0through=C2=A0linkTS4=C2=A0to=C2=A0linkSL8=C2= =A0to=C2=A0Leaf122=C2=A0or=C2=A0go=C2=A0up=C2=A0through
=C2=A0=C2=A0=C2= =A0linkSL5=C2=A0to=C2=A0linkTS6=C2=A0then=C2=A0go=C2=A0down=C2=A0through=C2= =A0linkTS4=C2=A0and=C2=A0linkSL8=C2=A0to
=C2=A0=C2=A0=C2=A0Leaf122=C2=A0= based=C2=A0on=C2=A0pure=C2=A0default=C2=A0route.=C2=A0=C2=A0It's=C2=A0t= he=C2=A0case=C2=A0of=C2=A0suboptimal
=C2=A0=C2=A0=C2=A0routing=C2=A0or= =C2=A0bow-tieing.

I=C2=A0think=C2=A0it=C2=A0should=C2=A0be=C2=A0cha= nged=C2=A0to=C2=A0the=C2=A0following:

=C2=A0=C2=A0=C2=A0Without=C2= =A0disaggregation=C2=A0mechanism,=C2=A0when=C2=A0linkSL6=C2=A0fails,=C2=A0t= he=C2=A0packet=C2=A0from
=C2=A0=C2=A0=C2=A0leaf121=C2=A0to=C2=A0prefix12= 2=C2=A0*may*=C2=A0go=C2=A0up=C2=A0through=C2=A0linkSL5=C2=A0to=C2=A0linkTS3=
=C2=A0=C2=A0=C2=A0then=C2=A0go=C2=A0down=C2=A0through=C2=A0linkTS4=C2= =A0to=C2=A0linkSL8=C2=A0to=C2=A0Leaf122=C2=A0or=C2=A0go=C2=A0up=C2=A0throug= h
=C2=A0=C2=A0=C2=A0linkSL5=C2=A0to=C2=A0linkTS6=C2=A0then=C2=A0go=C2=A0= down=C2=A0through=C2=A0*linkTS8*=C2=A0and=C2=A0linkSL8=C2=A0to
=C2=A0=C2= =A0=C2=A0Leaf122=C2=A0based=C2=A0on=C2=A0pure=C2=A0default=C2=A0route.=C2= =A0=C2=A0*This=C2=A0is*=C2=A0the=C2=A0case=C2=A0of=C2=A0suboptimal
=C2= =A0=C2=A0=C2=A0routing=C2=A0or=C2=A0bow-tieing.

The=C2=A0'*'= ;=C2=A0mark=C2=A0the=C2=A0changes.=C2=A0The=C2=A0second=C2=A0change=C2=A0is= =C2=A0to=C2=A0fix=C2=A0a=C2=A0mistake=C2=A0(I=C2=A0think).

=C2=A0<YuehuaWei17> linkTS3 is connectiong to ToF21, so the downlinks are=C2= =A0=C2=A0linkTS4=C2=A0+ linkSL8.=C2=A0 you were thinking of linkTS6 to ToF2= 2. I think both are right

w= ill change *may*=C2=A0 and *This=C2=A0is*=C2=A0>=C2=A0=C2=A0=C2=A0

It's=C2=A0the=C2=A0case=C2=A0of=C2=A0black-holing.


s/It&= #39;s/This=C2=A0is/

=C2=A0<Yue= huaWei18> OK=EF=BC=8Caccepted.= =C2=A0=C2=A0>

=C2= =A0=C2=A0=C2=A0...=C2=A0that=C2=A0is,=C2=A0on=C2=A0the=C2=A0one

=C2=A0= =C2=A0=C2=A0hand,=C2=A0the=C2=A0SystemID=C2=A0of=C2=A0the=C2=A0node=C2=A0th= at=C2=A0must=C2=A0be=C2=A0unique=C2=A0in=C2=A0the=C2=A0RIFT
=C2=A0=C2=A0= =C2=A0network,=C2=A0and=C2=A0on=C2=A0the=C2=A0other=C2=A0hand=C2=A0the=C2= =A0level=C2=A0of=C2=A0the=C2=A0node=C2=A0in=C2=A0the=C2=A0Fat=C2=A0Tree,=C2=A0=C2=A0=C2=A0which=C2=A0determines=C2=A0which=C2=A0peers=C2=A0are=C2= =A0northwards=C2=A0"parents"=C2=A0and=C2=A0which=C2=A0are
=C2= =A0=C2=A0=C2=A0southwards=C2=A0"children".

Perhaps=C2=A0c= hange=C2=A0to=C2=A0the=C2=A0following:

=C2=A0=C2=A0=C2=A0...=C2=A0i= ncluding=C2=A0SystemID=C2=A0of=C2=A0the=C2=A0node=C2=A0that=C2=A0must=C2=A0= be=C2=A0unique=C2=A0in=C2=A0the=C2=A0RIFT
=C2=A0=C2=A0=C2=A0network=C2= =A0and=C2=A0the=C2=A0level=C2=A0of=C2=A0the=C2=A0node=C2=A0in=C2=A0the=C2= =A0Fat=C2=A0Tree,
=C2=A0=C2=A0=C2=A0which=C2=A0determines=C2=A0which=C2= =A0peers=C2=A0are=C2=A0northwards=C2=A0"parents"=C2=A0and=C2=A0wh= ich=C2=A0are
=C2=A0=C2=A0=C2=A0southwards=C2=A0"children".
=

=C2=A0<YuehuaWei19> OK=EF=BC= =8Caccepted.=C2=A0=C2=A0>


The=C2=A0"b= ut"=C2=A0wording=C2=A0in=C2=A0the=C2=A0following=C2=A0is=C2=A0a=C2=A0b= it=C2=A0strange:

=C2=A0=C2=A0=C2=A0...=C2=A0it=C2=A0is
=C2=A0=C2= =A0=C2=A0recommended=C2=A0to=C2=A0configure=C2=A0the=C2=A0level=C2=A0of=C2= =A0all=C2=A0the=C2=A0nodes=C2=A0but=C2=A0those=C2=A0that
=C2=A0=C2=A0=C2= =A0are=C2=A0forced=C2=A0as=C2=A0leaves=C2=A0to=C2=A0avoid=C2=A0an=C2=A0unde= sirable=C2=A0interaction=C2=A0between=C2=A0ZTP
=C2=A0=C2=A0=C2=A0and=C2= =A0the=C2=A0manual=C2=A0configuration.

Do=C2=A0you=C2=A0mean=C2=A0&= quot;those=C2=A0that=C2=A0are=C2=A0forced=C2=A0as=C2=A0leaves"=C2=A0do= =C2=A0not=C2=A0need=C2=A0configuration?=C2=A0But=C2=A0then=C2=A0how=C2=A0ar= e=C2=A0they=C2=A0"forced=C2=A0as=C2=A0leaves"=C2=A0w/o=C2=A0confi= guration?

=C2=A0<YuehuaWei20&g= t;=C2=A0 =E5=90=AF=E7=94=A8zte=E7=9A=84=E6=97=B6=E5=80=99=EF=BC=8Cleaf=E8= =8A=82=E7=82=B9=E6=98=AF=E9=9C=80=E8=A6=81=E9=85=8D=E7=BD=AElevel=E7=9A=84= =EF=BC=9F>


??? ;-)

=C2=A0=C2=A0=C2= =A0A=C2=A0RIFT=C2=A0node=C2=A0may=C2=A0also=C2=A0be=C2=A0configured=C2=A0to= =C2=A0confine=C2=A0it=C2=A0to=C2=A0the=C2=A0leaf=C2=A0role

=C2=A0=C2=A0= =C2=A0with=C2=A0the=C2=A0LEAF_ONLY=C2=A0flag.=C2=A0=C2=A0A=C2=A0leaf=C2=A0n= ode=C2=A0can=C2=A0also=C2=A0be=C2=A0configured=C2=A0to
=C2=A0=C2=A0=C2= =A0support=C2=A0leaf-2-leaf=C2=A0procedures=C2=A0with=C2=A0the=C2=A0LEAF_2_= LEAF=C2=A0flag.=C2=A0=C2=A0In=C2=A0either
=C2=A0=C2=A0=C2=A0case=C2=A0th= e=C2=A0node=C2=A0cannot=C2=A0be=C2=A0TOP_OF_FABRIC=C2=A0and=C2=A0its=C2=A0l= evel=C2=A0cannot=C2=A0be
=C2=A0=C2=A0=C2=A0configured.=C2=A0=C2=A0RIFT= =C2=A0will=C2=A0fully=C2=A0configure=C2=A0the=C2=A0node's=C2=A0level=C2= =A0after=C2=A0it=C2=A0is
=C2=A0=C2=A0=C2=A0attached=C2=A0to=C2=A0the=C2= =A0topology=C2=A0and=C2=A0ensure=C2=A0that=C2=A0the=C2=A0node=C2=A0is=C2=A0= at=C2=A0the=C2=A0"bottom
=C2=A0=C2=A0=C2=A0of=C2=A0the=C2=A0hierarc= hy"=C2=A0(southernmost).

s/fully=C2=A0configure/fully=C2=A0det= ermine/

=C2=A0<YuehuaWei21>= Reasonable=EF=BC=8Caccepted.=C2= =A0>


=C2= =A0=C2=A0=C2=A0...=C2=A0So=C2=A0the=C2=A0ToF=C2=A0nodes=C2=A0can=C2=A0excha= nge=C2=A0the=C2=A0full=C2=A0list=C2=A0of
=C2=A0=C2=A0=C2=A0prefixes=C2= =A0that=C2=A0exist=C2=A0in=C2=A0the=C2=A0fabric=C2=A0and=C2=A0figure=C2=A0w= hen=C2=A0a=C2=A0ToF=C2=A0node=C2=A0lacks
=C2=A0=C2=A0=C2=A0reachability= =C2=A0and=C2=A0to=C2=A0existing=C2=A0prefix.

Is=C2=A0an=C2=A0"= out"=C2=A0needed=C2=A0after=C2=A0"figure",=C2=A0and=C2=A0sho= uld=C2=A0"and=C2=A0to=C2=A0existing=C2=A0prefix"=C2=A0be=C2=A0&qu= ot;to=C2=A0some=C2=A0prefixes"?

=C2=A0<YuehuaWei22> Right=EF=BC=8Caccepted.=C2=A0=C2=A0&= gt;


=C2=A0=C2=A0=C2=A0...=C2=A0In=C2=A0the=C2=A0case= =C2=A0of=C2=A0Negative=C2=A0Disaggregation,=C2=A0the=C2=A0last=C2=A0ToF
= =C2=A0=C2=A0=C2=A0node(s)=C2=A0that=C2=A0injects=C2=A0the=C2=A0route=C2=A0m= ay=C2=A0also=C2=A0incur=C2=A0an=C2=A0incast=C2=A0issue;=C2=A0this
=C2=A0= =C2=A0=C2=A0problem=C2=A0would=C2=A0occur=C2=A0if=C2=A0a=C2=A0prefix=C2=A0t= hat=C2=A0becomes=C2=A0totally=C2=A0unreachable=C2=A0is
=C2=A0=C2=A0=C2= =A0disaggregated,=C2=A0but=C2=A0doing=C2=A0so=C2=A0is=C2=A0mostly=C2=A0usel= ess=C2=A0and=C2=A0is=C2=A0not=C2=A0recommended.

What=C2=A0does=C2= =A0"so"=C2=A0refer=C2=A0to,=C2=A0in=C2=A0the=C2=A0last=C2=A0sente= nce=C2=A0above?

=C2=A0<YuehuaW= ei23> since this paragraph is talking about =E2=80=9Cnote=E2=80=9D, I wo= uld like to delete the last sentence.=C2=A0=C2=A0>


=C2=A0=C2=A0=C2=A0It=C2=A0is=C2=A0not=C2=A0envisioned=C2=A0in=C2= =A0the=C2=A0short=C2=A0term=C2=A0that=C2=A0the=C2=A0average=C2=A0fabric
= =C2=A0=C2=A0=C2=A0supports=C2=A0a=C2=A0Precision=C2=A0Time=C2=A0Protocol=C2= =A0[IEEEstd1588],=C2=A0and=C2=A0the=C2=A0precision
=C2=A0=C2=A0=C2=A0tha= t=C2=A0may=C2=A0be=C2=A0available=C2=A0with=C2=A0the=C2=A0Network=C2=A0Time= =C2=A0Protocol=C2=A0[RFC5905],=C2=A0in
=C2=A0=C2=A0=C2=A0the=C2=A0order= =C2=A0of=C2=A0100=C2=A0to=C2=A0200ms,=C2=A0may=C2=A0not=C2=A0be=C2=A0necess= arily=C2=A0enough=C2=A0to=C2=A0cover,
=C2=A0=C2=A0=C2=A0e.g.,=C2=A0the= =C2=A0fast=C2=A0mobility=C2=A0of=C2=A0a=C2=A0Virtual=C2=A0Machine.

= I=C2=A0struggled=C2=A0with=C2=A0the=C2=A0above=C2=A0paragraph.=C2=A0Perhaps= =C2=A0reword=C2=A0to=C2=A0the=C2=A0following?

=C2=A0<YuehuaWei24> Reasonable=EF=BC=8Caccepted.=C2=A0>

=C2=A0=C2=A0=C2=A0It=C2=A0is=C2=A0not=C2=A0envisio= ned=C2=A0that=C2=A0an=C2=A0average=C2=A0fabric=C2=A0supports=C2=A0Precision= =C2=A0Time=C2=A0Protocol

=C2=A0=C2=A0=C2=A0[IEEEstd1588]=C2=A0in=C2=A0th= e=C2=A0short=C2=A0term,=C2=A0nor=C2=A0that=C2=A0the=C2=A0precision=C2=A0ava= ilable=C2=A0with
=C2=A0=C2=A0=C2=A0the=C2=A0Network=C2=A0Time=C2=A0Proto= col=C2=A0[RFC5905]=C2=A0(in=C2=A0the=C2=A0order=C2=A0of=C2=A0100=C2=A0to=C2= =A0200ms)
=C2=A0=C2=A0=C2=A0may=C2=A0not=C2=A0be=C2=A0necessarily=C2=A0e= nough=C2=A0to=C2=A0cover,=C2=A0e.g.,=C2=A0the=C2=A0fast=C2=A0mobility=C2=A0= of=C2=A0a=C2=A0Virtual=C2=A0Machine.

Maybe=C2=A0even=C2=A0change=C2= =A0the=C2=A0double=C2=A0negative.

=C2=A0=C2=A0=C2=A0RIFT=C2=A0doesn= 't=C2=A0precondition=C2=A0that=C2=A0nodes=C2=A0of=C2=A0the=C2=A0fabric= =C2=A0have=C2=A0reachable
=C2=A0=C2=A0=C2=A0addresses.=C2=A0=C2=A0But=C2= =A0the=C2=A0operational=C2=A0purposes=C2=A0to=C2=A0reach=C2=A0the=C2=A0inte= rnal=C2=A0nodes
=C2=A0=C2=A0=C2=A0may=C2=A0exist.

s/purposes/rea= sons/?

=C2=A0<YuehuaWei25> = OK=EF=BC=8Caccepted.=C2=A0=C2=A0<= /span>>


=C2=A0= =C2=A0=C2=A0In=C2=A0a=C2=A0fully=C2=A0connected=C2=A0ToF,=C2=A0in=C2=A0case= =C2=A0of=C2=A0failure=C2=A0between=C2=A0ToF2=C2=A0and=C2=A0spine
=C2=A0= =C2=A0=C2=A0nodes,=C2=A0ToF2's=C2=A0loopback=C2=A0address=C2=A0must=C2= =A0be=C2=A0disaggregated=C2=A0recursively=C2=A0all
=C2=A0=C2=A0=C2=A0the= =C2=A0way=C2=A0to=C2=A0the=C2=A0leaves.

=C2=A0=C2=A0=C2=A0In=C2=A0a= =C2=A0partitioned=C2=A0ToF,=C2=A0a=C2=A0TOF=C2=A0node=C2=A0is=C2=A0only=C2= =A0reachable=C2=A0within=C2=A0its=C2=A0Plane,
=C2=A0=C2=A0=C2=A0and=C2= =A0the=C2=A0disaggregation=C2=A0to=C2=A0the=C2=A0leaves=C2=A0is=C2=A0also= =C2=A0required.=C2=A0=C2=A0A=C2=A0possible
=C2=A0=C2=A0=C2=A0alternative= =C2=A0is=C2=A0to=C2=A0use=C2=A0the=C2=A0ring=C2=A0that=C2=A0interconnects= =C2=A0the=C2=A0ToF=C2=A0nodes=C2=A0to
=C2=A0=C2=A0=C2=A0transmit=C2=A0pa= ckets=C2=A0between=C2=A0them=C2=A0for=C2=A0their=C2=A0loopback=C2=A0address= es=C2=A0only...

If=C2=A0I=C2=A0understand=C2=A0it=C2=A0correctly,= =C2=A0the=C2=A0above=C2=A0two=C2=A0paragraphs=C2=A0should=C2=A0be=C2=A0as= =C2=A0following=C2=A0(the=C2=A0ring=C2=A0alternative=C2=A0to=C2=A0recursive= =C2=A0disaggregation=C2=A0applies=C2=A0to=C2=A0both=C2=A0fully=C2=A0connect= ed=C2=A0ToF=C2=A0and=C2=A0partitioned=C2=A0ToF):

=C2=A0<YuehuaWei26> Better=EF=BC=8Caccepted<= span style=3D"color:rgb(255,0,0)">.=C2=A0=C2=A0>


=C2=A0=C2=A0=C2=A0In=C2=A0case=C2= =A0of=C2=A0failure=C2=A0between=C2=A0ToF2=C2=A0and=C2=A0spine
=C2=A0=C2= =A0=C2=A0nodes,=C2=A0ToF2's=C2=A0loopback=C2=A0address=C2=A0must=C2=A0b= e=C2=A0disaggregated=C2=A0recursively=C2=A0all
=C2=A0=C2=A0=C2=A0the=C2= =A0way=C2=A0to=C2=A0the=C2=A0leaves.=C2=A0In=C2=A0a=C2=A0partitioned=C2=A0T= oF,=C2=A0even=C2=A0with=C2=A0recursive=C2=A0disaggregation
=C2=A0=C2=A0= =C2=A0a=C2=A0ToF=C2=A0node=C2=A0is=C2=A0only=C2=A0reachable=C2=A0within=C2= =A0its=C2=A0plane.

=C2=A0=C2=A0=C2=A0A=C2=A0possible=C2=A0alternati= ve=C2=A0to=C2=A0recursive=C2=A0disaggregation=C2=A0is=C2=A0to=C2=A0use=C2= =A0a=C2=A0ring
=C2=A0=C2=A0=C2=A0that=C2=A0interconnects=C2=A0the=C2=A0T= oF=C2=A0nodes=C2=A0to
=C2=A0=C2=A0=C2=A0transmit=C2=A0packets=C2=A0betwe= en=C2=A0them=C2=A0for=C2=A0their=C2=A0loopback=C2=A0addresses=C2=A0only...<= br>
For=C2=A0the=C2=A0following:

=C2=A0=C2=A0=C2=A0If=C2=A0a=C2= =A0controller=C2=A0is=C2=A0attaching=C2=A0to=C2=A0the=C2=A0RIFT=C2=A0domain= =C2=A0from=C2=A0ToF,=C2=A0it=C2=A0usually
=C2=A0=C2=A0=C2=A0uses=C2=A0du= al-homing=C2=A0connections.=C2=A0=C2=A0The=C2=A0loopback=C2=A0prefix=C2=A0o= f=C2=A0the=C2=A0controller
=C2=A0=C2=A0=C2=A0should=C2=A0be=C2=A0adverti= sed=C2=A0down=C2=A0by=C2=A0the=C2=A0ToF=C2=A0and=C2=A0spine=C2=A0to=C2=A0le= aves.=C2=A0=C2=A0If=C2=A0the
=C2=A0=C2=A0=C2=A0controller=C2=A0loses=C2= =A0link=C2=A0to=C2=A0ToF,=C2=A0make=C2=A0sure=C2=A0the=C2=A0ToF=C2=A0withdr= aw=C2=A0the=C2=A0prefix
=C2=A0=C2=A0=C2=A0of=C2=A0the=C2=A0controller(us= e=C2=A0different=C2=A0mechanisms).

What=C2=A0does=C2=A0"(use= =C2=A0different=C2=A0mechanisms)"=C2=A0mean?

=C2=A0<YuehuaWei27> the interworking between contro= ller and ToF is outside of RIFT domain. so ToF withdraw the prefix of the c= ontroller will use different mechanisms other than RIFT=C2=A0=C2=A0>

5.12.=C2=A0=C2=A0Internet=C2=A0Connectivity=C2=A0With= =C2=A0Underlay


s/With/Within/?

=C2=A0<YuehuaWei28> Better=EF=BC=8Caccepted.=C2=A0=C2=A0>


=C2=A0=C2=A0=C2=A0In=C2=A0case=C2=A0that=C2=A0an= =C2=A0internet=C2=A0access=C2=A0request=C2=A0comes=C2=A0from=C2=A0a=C2=A0le= af=C2=A0and=C2=A0the
=C2=A0=C2=A0=C2=A0internet=C2=A0gateway=C2=A0is=C2= =A0another=C2=A0leaf=C2=A0...

Where=C2=A0else=C2=A0could=C2=A0the= =C2=A0internet=C2=A0access=C2=A0request=C2=A0come=C2=A0from?=C2=A0With=C2= =A0the=C2=A0request=C2=A0from=C2=A0a=C2=A0non-leaf,=C2=A0don't=C2=A0you= =C2=A0also=C2=A0need=C2=A0the=C2=A0default=C2=A0route=C2=A0to=C2=A0be=C2=A0= advertised=C2=A0by=C2=A0the=C2=A0internet=C2=A0gateway?

=C2=A0<YuehuaWei29>"5.12.2.=C2=A0 Internet Default on the ToFs" is the= other case. >


yeah, it's complex, people will get confused. yo= u have to stop to advertise in RIFT a default but use a "fabric-defaul= t" or have preference rules.
=C2=A0
<= div id=3D"gmail-m_-7040598385886456083gmail-m_4211057490630903466zwriteHist= oryContainer">


=C2=A0=C2=A0=C2=A0If=C2=A0the=C2=A0traff= ic=C2=A0comes=C2=A0from=C2=A0ToF=C2=A0to=C2=A0Leaf111=C2=A0or=C2=A0Leaf121= =C2=A0which=C2=A0has=C2=A0anycast
=C2=A0=C2=A0=C2=A0prefix=C2=A0PrefixA.= =C2=A0=C2=A0RIFT=C2=A0can=C2=A0deal=C2=A0with=C2=A0this=C2=A0case=C2=A0well= .

s/.=C2=A0RIFT/,=C2=A0RIFT/

=C2=A0<YuehuaWei30> OK=EF=BC=8Caccepted.=C2=A0=C2=A0>=


=C2=A0=C2=A0=C2=A0The=C2=A0adds=C2=A0huge
=C2=A0= =C2=A0=C2=A0capabilities=C2=A0for=C2=A0leaf-2-leaf=C2=A0ECMP=C2=A0paths,=C2= =A0but=C2=A0additional=C2=A0complexity
=C2=A0=C2=A0=C2=A0with=C2=A0the= =C2=A0need=C2=A0to=C2=A0disaggregate.=C2=A0=C2=A0Also=C2=A0RIFT=C2=A0uses= =C2=A0Link=C2=A0State=C2=A0flooding
=C2=A0=C2=A0=C2=A0northwards,=C2=A0a= nd=C2=A0is=C2=A0not=C2=A0designed=C2=A0for=C2=A0low-power=C2=A0operation.

s/The/This/

=C2=A0<Yu= ehuaWei31> OK=EF=BC=8Caccepted= .=C2=A0=C2=A0>

Why= =C2=A0is=C2=A0low-poer=C2=A0operation=C2=A0mentioned=C2=A0all?=C2=A0It'= s=C2=A0not=C2=A0like=C2=A0that=C2=A0we'll=C2=A0run=C2=A0RIFT=C2=A0on=C2= =A0IOTs?=C2=A0The=C2=A0following=C2=A0only=C2=A0talks=C2=A0about=C2=A0IOT= =C2=A0being=C2=A0attached=C2=A0to=C2=A0leaves:

=C2=A0<YuehuaWei32> You are right, But I think the firs= t two paragraphs of this section is talking about RIFT design principles an= d applicability in general. The third paragraph=C2=A0 starts to talk about= =C2=A0=C2=A0IOT=C2=A0being=C2=A0attached=C2=A0to=C2=A0leaves>

=C2=A0=C2=A0=C2=A0Still=C2=A0n= othing=C2=A0prevents=C2=A0that=C2=A0the=C2=A0IP=C2=A0devices=C2=A0connected= =C2=A0at=C2=A0the=C2=A0Leaf=C2=A0are

=C2=A0=C2=A0=C2=A0IoT=C2=A0(Interne= t=C2=A0of=C2=A0Things)=C2=A0devices,=C2=A0which=C2=A0typically=C2=A0expose= =C2=A0their
=C2=A0=C2=A0=C2=A0address=C2=A0using=C2=A0WiND=C2=A0-=C2=A0w= hich=C2=A0is=C2=A0an=C2=A0upgrade=C2=A0from=C2=A06LoWPAN=C2=A0ND=C2=A0[RFC6= 775].=C2=A0

And=C2=A0are=C2=A0the=C2=A0following=C2=A0specific=C2= =A0to=C2=A0IOT?

=C2=A0<YuehuaW= ei33>The following is not specific to IoT, but it doesn't=C2=A0 viol= ate the topic of this section?>

=C2=A0=C2=A0=C2=A0A=C2=A0ne= twork=C2=A0that=C2=A0serves=C2=A0high=C2=A0speed/=C2=A0high=C2=A0power=C2= =A0IoT=C2=A0devices=C2=A0should

=C2=A0=C2=A0=C2=A0typically=C2=A0provide= =C2=A0deterministic=C2=A0capabilities=C2=A0for=C2=A0applications=C2=A0such= =C2=A0as
=C2=A0=C2=A0=C2=A0high=C2=A0speed=C2=A0control=C2=A0loops=C2=A0= or=C2=A0movement=C2=A0detection.=C2=A0=C2=A0The=C2=A0Fat=C2=A0Tree=C2=A0is<= br>=C2=A0=C2=A0=C2=A0highly=C2=A0reliable,=C2=A0and=C2=A0in=C2=A0normal=C2= =A0condition=C2=A0provides=C2=A0an=C2=A0equilatent
=C2=A0=C2=A0=C2=A0mul= tipath=C2=A0operation;=C2=A0but=C2=A0the=C2=A0ECMP=C2=A0doesn't=C2=A0pr= ovide=C2=A0hard=C2=A0guarantees=C2=A0for
=C2=A0=C2=A0=C2=A0either=C2=A0d= elivery=C2=A0or=C2=A0latency.=C2=A0=C2=A0As=C2=A0long=C2=A0as=C2=A0the=C2= =A0fabric=C2=A0is=C2=A0non-blocking
=C2=A0=C2=A0=C2=A0the=C2=A0result=C2= =A0is=C2=A0the=C2=A0same;=C2=A0but=C2=A0there=C2=A0can=C2=A0be=C2=A0load=C2= =A0unbalances=C2=A0resulting=C2=A0in
=C2=A0=C2=A0=C2=A0incast=C2=A0and= =C2=A0possibly=C2=A0congestion=C2=A0loss=C2=A0that=C2=A0will=C2=A0prevent= =C2=A0the=C2=A0delivery
=C2=A0=C2=A0=C2=A0within=C2=A0bounded=C2=A0laten= cy.

=C2=A0=C2=A0=C2=A0This=C2=A0could=C2=A0be=C2=A0alleviated=C2=A0= with=C2=A0Packet=C2=A0Replication,=C2=A0Elimination=C2=A0and
=C2=A0=C2= =A0=C2=A0Reordering=C2=A0(PREOF)=C2=A0[RFC8655]=C2=A0leaf-2-leaf=C2=A0but= =C2=A0PREOF=C2=A0is=C2=A0hard=C2=A0to=C2=A0provide
=C2=A0=C2=A0=C2=A0at= =C2=A0the=C2=A0scale=C2=A0of=C2=A0all=C2=A0flows,=C2=A0and=C2=A0the=C2=A0re= plication=C2=A0may=C2=A0increase=C2=A0the
=C2=A0=C2=A0=C2=A0probability= =C2=A0of=C2=A0the=C2=A0overload=C2=A0that=C2=A0it=C2=A0attempts=C2=A0to=C2= =A0solve.

Thanks!
Jeffrey
___________________________________= ____________
RIFT=C2=A0mailing=C2=A0list
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