> On Apr 2, 2020, at 5:17 PM, 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.
[as wg member] Are you thinking that shifting traffic to a router is not going to affect it's jitter/drop rate? > 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. will reply separately to this. Thanks, Chris. > > 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
