> On Apr 2, 2020, at 6:28 PM, Robert Raszuk <rob...@raszuk.net> wrote: > > Well Jeff if you would completely remove CSPF and Flex Algo from IGPs I am > fully with you. > > But till we still have them running in the routers I am of the opinion that > we need both ... bigger and slower PCE based path computation and sufficient > information (not only static data) for routers itself to be able to adjust > forwarding state based on the live path constraints. > > I realize I am thinking outside of the box here but hopefully one day this > will become a norm rather then abstraction :)
You don't need the IGP advertising this stuff in order to do anything you've suggested. Thanks, Chris. [as WG member] > Best, > R., > > On Fri, Apr 3, 2020 at 12:24 AM Jeff Tantsura <jefftant.i...@gmail.com> wrote: > Robert, > > That is why we have a possibility to signal in-band/as per device data that > could be used by PCE to compute a path that meets the constrains (RFC > 7471/7810), e.g per node BW reserved/available or cumulative delay, and > similar, computed by the PCE. > However if the objective functions used by CSPF are coming from outside > (end2end latency measurement/$$ of a link as an example) we don’t feed them > back into IGP, telemetry analysis (done by an external system) are of no > business of IGP and should be fed (normalized) into PCE directly. > We are not discussing the value of telemetry, which is obvious, but need to > autodiscover telemetry capability’s and feed (pollute) them into > IGP->BGP-LS->controller. > I don’t see how this information would be used in route/path computation and > hence IMHO it doesn’t belong in IGP. Given the need for configuration > (besides ability to support particular technology) makes this a clear > candidate for management plane operations. (Chris’ comment about YANG) > > Cheers, > Jeff > On Apr 2, 2020, 2:17 PM -0700, Robert Raszuk <rob...@raszuk.net>, wrote: >> Jeff. >> >> > The role of a routing protocol is to distribute: reachability (doh :-)) >> > and any additional data that could influence routing decision wrt >> > reachability. >> >> The bolded text is precisely the point here. >> >> So let me provide a very simple example. >> >> Today routers already compute CSPF. Moreover today routers are asked to use >> custom/flexible algorithm to choose reachability paths. >> >> So just imagine an operator who says: >> >> Please compute my SPT with the consideration that end to end inband jitter >> is not greater then 10 ms otherwise I do not want to see nodes which do not >> meet that criteria in the reachability graph for application X. >> >> or >> >> Please compute my SPT with the consideration that end to end drop rate is >> not greater then 5pps otherwise I do not want to see nodes which do not >> meet that criteria in the reachability graph for application Y. >> >> etc ... >> >> If you consider such constrains to provide reachability for applications you >> will likely see value that in-situ telemetry is your friend here. Really >> best friend as without him you can not do the proper end to end path >> exclusion for SPT computations. >> >> Hint: All per link extensions which were added to IGPs are not going to help >> here as drops or jitter may equally happen in the routers fabric on fabric >> to LC boundaries or on the line cards and links. So you need end to end test >> stream. >> >> Many thx, >> R. >> >> PS. As we are talking LSR here it is strange that joining virtual LSR >> meeting is not for everyone. I was waiting and tried three times today for >> host approval to join which was not granted. >> >> On Thu, Apr 2, 2020 at 11:00 PM Jeff Tantsura <jefftant.i...@gmail.com> >> wrote: >> Robert, >> >> This is unnecessary leakage of management plane into control plane. >> The role of a routing protocol is to distribute: reachability (doh :-)) and >> any additional data that could influence routing decision wrt reachability. >> There are precedences of using IGP’s for different tasks, e.g. RFC 5088 and >> similar, however should we do it again? >> >> Specifically to use case described - I really don’t see how this information >> would be used in routing decisions (PCE computation). Moreover, if the >> end-goal is to build a connected graph of the devices that have a coherent >> iFIT feature set it would require reoptimization on every change and quite >> complex computation logic (talking SR - on top of regular constrains, MSD, >> etc).I’d also think that there’s mandatory configuration of name-spaces and >> features supported, in other words - autodiscovery is meaningless, it would >> still require as per device configuration (hello YANG). Most of telemetry >> solutions are designed to pass thought nodes that don’t support it >> transparently, so the real requirement is really to know the sink-node (the >> one that is egress of the telemetry domain and must remove all additional >> encapsulations). >> >> As to the last point - we already have a kitchen-sink routing protocol ;-) >> >> Cheers, >> Jeff >> On Apr 2, 2020, 6:10 AM -0700, Robert Raszuk <rob...@raszuk.net>, wrote: >>> >>> Hi Les, >>> >>> Ok very well. >>> >>> So till this draft provides a text or reference to some other document how >>> IGPs may use inband telemetry data for real path selection it does not fit >>> to LSR charter. Fair. >>> >>> Hi Chris, >>> >>> I am afraid we are looking at this from completely different perspectives. >>> >>> I consider this data to be a necessity for routing and you simply treat it >>> as some opaque telemetry. If we would think of it in the latter sense sure >>> you would be right. IGP is not a configuration push protocol. Sufficient to >>> observe how BGP became one :) >>> >>> Many thx, >>> R. >>> >>> >>> On Thu, Apr 2, 2020 at 8:46 AM Les Ginsberg (ginsberg) <ginsb...@cisco.com> >>> wrote: >>> Robert - >>> >>> First, +1 to what Chris has said. >>> >>> There is nothing in the lfit-capability draft that defines any information >>> that can be used by IGPs to do what you suggest. >>> Perhaps it is possible that information gleaned via a telemetry application >>> could be used by the IGPs to do something like what you suggest - but this >>> draft is not discussing/defining that. It is simply proposing to advertise >>> information about the capabilities of the lfit application on a given node.. >>> >>> Les >>> >>> > -----Original Message----- >>> > From: Christian Hopps <cho...@chopps.org> >>> > Sent: Thursday, April 02, 2020 5:13 AM >>> > To: Robert Raszuk <rob...@raszuk.net> >>> > Cc: Christian Hopps <cho...@chopps.org>; Les Ginsberg (ginsberg) >>> > <ginsb...@cisco.com>; wangyali <wangyal...@huawei.com>; Acee Lindem >>> > (acee) <a...@cisco.com>; l...@ietf..org; Tianran Zhou >>> > <zhoutian...@huawei.com> >>> > Subject: Re: [Lsr] A new version of I-D, >>> > draft-liu-lsr-isis-ifit-node-capability-02 >>> > >>> > We have defined a perfectly acceptable and quite powerful way to do query >>> > and configuration for routers, it's YANG. I'd like to hear why the the >>> > IETF >>> > standard mechanism for query and configuration can't work for this >>> > application. >>> > >>> > Telemetry is important, I don't think anyone has said or would say that >>> > it isn't, >>> > but that seems orthogonal to this discussion. >>> > >>> > Thanks, >>> > Chris. >>> > [as WG member] >>> > >>> > >>> > > On Apr 2, 2020, at 5:17 AM, Robert Raszuk <rob...@raszuk.net> wrote: >>> > > >>> > > Hi Les, >>> > > >>> > > I would like to respectfully disagree with your assessment. >>> > > >>> > > The fact that today's IGP (or for that matter BGP) routing is static >>> > > from the >>> > perspective of not taking into consideration real performance measurements >>> > from the data plane to me is a bug not a feature. >>> > > >>> > > Building SPT based on static link metrics which in vast majority of >>> > > cases >>> > today are emulated circuits on someone else IP backbone. It was a great >>> > idea >>> > when you constructed the network with connection oriented paradigm >>> > (Sonet,SDH, dark fiber, TDM ...) not connection less often best effort >>> > one. >>> > > >>> > > So I find this proposal very useful and would vote for adopting it in >>> > > LSR WG. >>> > To me in-situ telemetry is not just some monitoring tool. It is an >>> > extremely >>> > important element to influence how we compute reachability or at least how >>> > we choose active forwarding paths from protocol RIBs to main RIB. >>> > > >>> > > If we extended IGPs to carry TE information, if we extended them to >>> > enable flexible algorithm based path computation I fail to understand why >>> > would we resist to natively enable all of the above with getting the >>> > inputs >>> > from real networks to be used as to the parameters to the above mentioned >>> > tools. >>> > > >>> > > Kind regards, >>> > > R. >>> > > >>> > > On Thu, Apr 2, 2020 at 8:32 AM Les Ginsberg (ginsberg) >>> > <ginsberg=40cisco....@dmarc.ietf.org> wrote: >>> > > Yali - >>> > > >>> > > There is a very significant difference between having IGPs advertise an >>> > identifier for a service that they use as clients (BFD) and having IGPs >>> > advertise a set of capabilities/options for a telemetry application which >>> > has >>> > no direct bearing on the function of the routing protocol. >>> > > >>> > > You are not the first to find using IGPs to flood application >>> > > information very >>> > convenient. But this is not the appropriate role for the IGPs and over >>> > the >>> > years we have consistently resisted attempts to do so. >>> > > >>> > > Everything advertised in Router Capabilities today has some close >>> > relationship with the operation of the protocol. Do some of the existing >>> > advertisements "bend the rules" a bit more than I would prefer? Yes - but >>> > there has always been at least a close relationship to routing protocol >>> > function. >>> > > Here there is none. >>> > > >>> > > If you feel compelled to use IGPs to advertise application information, >>> > > you >>> > have RF6823 available (at least for IS-IS). But it is a "high bar" since >>> > it requires >>> > you also to use a separate IS-IS instance dedicated to advertising the >>> > application information (see RFC8202). >>> > > I think Chris Hopps's suggestion to use Netconf/YANG to >>> > > configure/retrieve >>> > what you need is most likely more attractive - but I will leave that for >>> > you to >>> > decide. >>> > > >>> > > Using IGP Router Capabilities here is wrong in my view. >>> > > >>> > > Les >>> > > >>> > > >>> > > > -----Original Message----- >>> > > > From: wangyali <wangyal...@huawei.com> >>> > > > Sent: Wednesday, April 01, 2020 8:12 PM >>> > > > To: Acee Lindem (acee) <a...@cisco.com>; Les Ginsberg (ginsberg) >>> > > > <ginsb...@cisco.com>; Christian Hopps <cho...@chopps.org> >>> > > > Cc: lsr@ietf.org; Tianran Zhou <zhoutian...@huawei.com> >>> > > > Subject: 答复: [Lsr] A new version of I-D, draft-liu-lsr-isis-ifit-node- >>> > capability- >>> > > > 02 >>> > > > >>> > > > Hi Acee, Chris and Les, >>> > > > >>> > > > This is Yali. Many thanks for your kind comments and suggestion. >>> > > > >>> > > > Besides of signaling MSD by IGP node CAPABILITY TLV, we learned that >>> > > > there's another RFC7883 that advertising S-BFD discriminators in >>> > > > IS-IS. In >>> > my >>> > > > understand, BFD is a protocol to detect faults in the bidirectional >>> > > > path >>> > > > between two forwarding engines, including interface, data links, etc. >>> > > > >>> > > > Similarly, IFIT provides a complete framework of a family of on-path >>> > > > telemetry techniques, which are used to monitoring performance metrics >>> > of >>> > > > service flows, e.g. packet loss, delay. So we consider there's a same >>> > > > methodology with S-BFD that advertising IFIT node capabilities. >>> > > > >>> > > > Please let us know your comments and opinion. Thanks. >>> > > > >>> > > > Best regards, >>> > > > Yali >>> > > > >>> > > > -----邮件原件----- >>> > > > 发件人: Acee Lindem (acee) [mailto:a...@cisco.com] >>> > > > 发送时间: 2020年4月1日 20:29 >>> > > > 收件人: Tianran Zhou <zhoutian...@huawei.com>; Les Ginsberg >>> > (ginsberg) >>> > > > <ginsb...@cisco.com>; Christian Hopps <cho...@chopps.org> >>> > > > 抄送: lsr@ietf.org; wangyali <wangyal...@huawei.com> >>> > > > 主题: Re: [Lsr] A new version of I-D, >>> > > > draft-liu-lsr-isis-ifit-node-capability- >>> > 02 >>> > > > >>> > > > Speak as WG Member... >>> > > > >>> > > > On 4/1/20, 8:08 AM, "Acee Lindem (acee)" <a...@cisco.com> wrote: >>> > > > >>> > > > There is also a difference between some of the existing >>> > > > applications >>> > > > advertised in IGP capabilities. For example, MSD is used with the >>> > > > routing >>> > > > information to construct SR paths. The information for all these OAM >>> > > > mechanisms doesn't share this affinity. Also, it seems like a >>> > > > slippery slope >>> > in >>> > > > what is needed for each of the mechanism. >>> > > > Thanks, >>> > > > Acee >>> > > > >>> > > > On 4/1/20, 4:01 AM, "Lsr on behalf of Tianran Zhou" <lsr- >>> > boun...@ietf.org >>> > > > on behalf of zhoutian...@huawei.com> wrote: >>> > > > >>> > > > Hi Les, >>> > > > >>> > > > Thanks very much for your suggestion. I have a quick look at >>> > > > rfc6823. >>> > > > Sounds like a good idea. I will think about it. >>> > > > >>> > > > Cheers, >>> > > > Tianran >>> > > > >>> > > > -----Original Message----- >>> > > > From: Les Ginsberg (ginsberg) [mailto:ginsb...@cisco.com] >>> > > > Sent: Wednesday, April 1, 2020 1:47 PM >>> > > > To: Tianran Zhou <zhoutian...@huawei.com>; Christian Hopps >>> > > > <cho...@chopps.org> >>> > > > Cc: wangyali <wangyal...@huawei.com>; lsr@ietf.org >>> > > > Subject: RE: [Lsr] A new version of I-D, >>> > > > draft-liu-lsr-isis-ifit-node- >>> > > > capability-02 >>> > > > >>> > > > Tianran - >>> > > > >>> > > > I am very much in agreement with the points Chris has made. >>> > > > >>> > > > IGPs do not exist to advertise capabilities/configure >>> > > > applications - >>> > which >>> > > > seems to me to be what you are proposing here. >>> > > > The fact that you can easily define the encodings does not >>> > > > make it >>> > the >>> > > > right thing to do. >>> > > > >>> > > > This issue was discussed at length in the context of >>> > > > https://tools.ietf.org/html/rfc6823 . If you were proposing to use >>> > GENAPP I >>> > > > would not object - though I do think Chris has correctly pointed out >>> > > > that >>> > > > NETCONF/YANG is likely a more appropriate solution for your use case. >>> > > > >>> > > > Les >>> > > > >>> > > > >>> > > > > -----Original Message----- >>> > > > > From: Tianran Zhou <zhoutian...@huawei.com> >>> > > > > Sent: Tuesday, March 31, 2020 7:53 PM >>> > > > > To: Christian Hopps <cho...@chopps.org> >>> > > > > Cc: wangyali <wangyal...@huawei.com>; Les Ginsberg >>> > > > (ginsberg) >>> > > > > <ginsb...@cisco.com>; lsr@ietf.org >>> > > > > Subject: RE: [Lsr] A new version of I-D, >>> > > > > draft-liu-lsr-isis-ifit-node-capability-02 >>> > > > > >>> > > > > Hi Chris, >>> > > > > Thanks for your quick reply, and please see inline. >>> > > > > >>> > > > > Cheers, >>> > > > > Tianran >>> > > > > >>> > > > > -----Original Message----- >>> > > > > From: Christian Hopps [mailto:cho...@chopps.org] >>> > > > > Sent: Wednesday, April 1, 2020 10:00 AM >>> > > > > To: Tianran Zhou <zhoutian...@huawei.com> >>> > > > > Cc: Christian Hopps <cho...@chopps.org>; wangyali >>> > > > > <wangyal...@huawei.com>; Les Ginsberg (ginsberg) >>> > > > <ginsb...@cisco.com>; >>> > > > > lsr@ietf.org >>> > > > > Subject: Re: [Lsr] A new version of I-D, >>> > > > > draft-liu-lsr-isis-ifit-node-capability-02 >>> > > > > >>> > > > > >>> > > > > >>> > > > > > On Mar 31, 2020, at 9:28 PM, Tianran Zhou >>> > > > <zhoutian...@huawei.com> >>> > > > > wrote: >>> > > > > > >>> > > > > > ZTR> Let's not boil the ocean to compare NETCONF/YANG or >>> > routing >>> > > > > protocol, which is better. But I did not see the >>> > > > modification to >>> > > > > routing protocol with some TLVs is a heavy work, or more >>> > > > complex >>> > than >>> > > > > NETCONF/YANG. I see both are available and useful. >>> > > > > >>> > > > > I'm not sure what you mean by boiling the ocean. I'm saying >>> > > > that >>> > YANG >>> > > > > is built and intended for querying capabilities and >>> > > > configuring >>> > > > > routers. Why isn't that where you are looking first for >>> > > > configuring >>> > your >>> > > > monitoring application? >>> > > > > >>> > > > > ZTR> I know NETCONF can do both query and configuration. >>> > > > And I >>> > > > know >>> > > > > resent YANG-Push improvements to reduce the polling. But >>> > routing >>> > > > > protocol solutions are also widely used for this. There are >>> > > > already >>> > > > > many RFCs and implementation practices. We considered both >>> > ways, >>> > > > and >>> > > > > aimed for different scenarios. >>> > > > > >>> > > > > You don't see the major difference between writing a YANG >>> > > > model >>> > vs >>> > > > > modifying all of the standard IETF routing protocols? >>> > > > > >>> > > > > ZTR> I know many differences between NETCONF and routing >>> > > > protocol. >>> > > > > There are many details on both interfaces, implementations, >>> > scenarios >>> > > > > when comparing them. That's what I mean boil the ocean. >>> > > > > Here I do not know what's the "major difference" you mean? >>> > > > > >>> > > > > Thanks, >>> > > > > Chris. >>> > > > >>> > > > _______________________________________________ >>> > > > Lsr mailing list >>> > > > Lsr@ietf.org >>> > > > https://www..ietf.org/mailman/listinfo/lsr >>> > > > >>> > > > >>> > > > >>> > > >>> > > _______________________________________________ >>> > > Lsr mailing list >>> > > Lsr@ietf.org >>> > > https://www.ietf.org/mailman/listinfo/lsr >>> >>> _______________________________________________ >>> Lsr mailing list >>> Lsr@ietf.org >>> https://www.ietf.org/mailman/listinfo/lsr _______________________________________________ Lsr mailing list Lsr@ietf.org https://www.ietf.org/mailman/listinfo/lsr
