Peter, If this is per app how are the constraints shared across apps ?
See we have single physical resources (for example links) and single interface outbound queues. If I use per app flex-algo and do not have central controller how is this going to work in practice for any network which attempts to use more then one forwarding schema with dynamic constraints ? Many thx, R. On Tue, Oct 13, 2020 at 10:52 AM Peter Psenak <ppsenak= [email protected]> wrote: > Hi Jimmy, > > On 13/10/2020 10:02, Dongjie (Jimmy) wrote: > > Hi Peter, > > > > Thanks for your reply. Please see further inline: > > > >> -----Original Message----- > >> From: Lsr [mailto:[email protected]] On Behalf Of Peter Psenak > >> Sent: Monday, October 12, 2020 4:39 PM > >> To: Dongjie (Jimmy) <[email protected]>; Ron Bonica > >> <[email protected]>; Yingzhen Qu <[email protected]>; Gyan > >> Mishra <[email protected]> > >> Cc: [email protected]; Jeff Tantsura <[email protected]> > >> Subject: Re: [Lsr] FW: New Version Notification for > >> draft-bonica-lsr-ip-flexalgo-00.txt > >> > >> Hi Jimmy, > >> > >> On 10/10/2020 05:05, Dongjie (Jimmy) wrote: > >>> Hi Peter, > >>> > >>> Thanks for your reply. It aligns with my understanding of FAD, which > is just a > >> set of constraints for path computation. Thus one Flex-Algo ID could be > used > >> with multiple different data planes. Is this understanding correct? > >> > >> correct. > >> > >>> > >>> If so, my question is about the scenario below: > >>> > >>> A group of nodes in a network support FA-128, a sub-group of them bind > >> FA-128 to SR SIDs, another sub-group of them bind FA-128 to IP address. > >> > >> just to use the correct terminology, we should use "participate" > instead of > >> "support". > > > > Agree. > > > >> > >>> When one node compute an SR path to a destination, can it compute the > path > >> to only pass the nodes which bind FA-128 to SR SIDs, and avoid the > >> nodes >which bind FA-128 to IP address? If so, how could this node know > the > >> binding of FA to different data planes on other nodes? > >> > >> again, it is the participation problem. > >> > >> Nodes that participate in the SR Flex-algo 128 will advertise the > participation > >> using the SR-Algorithm Sub-TLV. Only these nodes will be used during > the SR > >> flex-algo computation for algo 128. > >> > >> Nodes that participate in IP flex-algo 128 will advertise the > participation using > >> the IGP Algorithm Sub-TLV. Only these nodes will be used during the IP > flex-algo > >> computation for algo 128. > > > > Agree that if participation to Flex-Algo is advertised in a data plane > specific manner, then path computation with Flex-Algo constraints could be > done only using nodes which bind the Flex-Algo to the same data plane. > > it's per app, not per data plane, but yes, that is what the base > flex-algo spec mandates. > > > > > As Robert asked and you confirmed, this implies each data plane needs to > be treated as an independent application of Flex-Algo. We have SR-Algorithm > sub-TLV and IP Algorithm sub-TLV, while there are actually more data planes > to be considered: SR-MPLS, SRv6, IPv4, IPv6, etc., does this mean that > Flex-Algo participation needs to be advertised for SR-MPLS, SRv6, IPv4, > IPv6, etc. separately? > > yes, it needs to be advertised per app. We have SR specific algo > participation, we need one for IP as proposed in Ron's draft. > > Regarding IPv4 vs IPv6, it's up to the authors whether they want to make > the participation for IP flex-algo topology specific or topology > independent, both could work. > > Here's the text from the base flerx-algo draft: > > 10.2. Advertisement of Node Participation for Other Applications > > This section describes considerations related to how other > applications can advertise their participation in a specific Flex- > Algorithm. > > Application-specific Flex-Algorithm participation advertisements MAY > be topology specific or MAY be topology independent, depending on the > application itself. > > Application-specific advertisement for Flex-Algorithm participation > MUST be defined for each application and is outside of the scope of > this document. > > thanks, > Peter > > > > > > Best regards, > > Jie > > > >> > >> thanks, > >> Peter > >> > >>> > >>> Best regards, > >>> Jie > >>> > >>>> -----Original Message----- > >>>> From: Lsr [mailto:[email protected]] On Behalf Of Peter Psenak > >>>> Sent: Friday, October 9, 2020 11:58 PM > >>>> To: Dongjie (Jimmy) <[email protected]>; Ron Bonica > >>>> <[email protected]>; Yingzhen Qu > >>>> <[email protected]>; Gyan Mishra <[email protected]> > >>>> Cc: [email protected]; Jeff Tantsura <[email protected]> > >>>> Subject: Re: [Lsr] FW: New Version Notification for > >>>> draft-bonica-lsr-ip-flexalgo-00.txt > >>>> > >>>> Hi Jimmy, > >>>> > >>>> > >>>> On 09/10/2020 04:59, Dongjie (Jimmy) wrote: > >>>>> Hi Ron, > >>>>> > >>>>> Thanks for explaining the difference between IP Flex-Algo and SR > >>>>> Flex-algo. As > >>>> you said, the major difference is the data plane. > >>>>> > >>>>> If my understanding is correct, for one Flex-Algo to be used > >>>>> correctly, the set > >>>> of nodes need to apply consistent constraints in computation, and > >>>> bind the FAD to the same data plane. > >>>>> > >>>>> Is it possible that different nodes may use the same Flex-Algo with > >>>>> different > >>>> data plane, e.g. some with SR-MPLS, some with SRv6, and some with > >>>> pure IP etc., or each Flex-Algo is always associated with only one > >>>> data plane? In the former case, should the flex-algo definition also > >>>> indicate the data plane(s) to be used with the flex-algo? > >>>> > >>>> let me respond to this query, as this is not specific to Ron's draft. > >>>> > >>>> FAD is data plane agnostic and is used by all of them. > >>>> > >>>> thanks, > >>>> Peter > >>>> > >>>>> > >>>>> Best regards, > >>>>> Jie > >>>>> > >>>>>> -----Original Message----- > >>>>>> From: Lsr [mailto:[email protected]] On Behalf Of Ron Bonica > >>>>>> Sent: Sunday, October 4, 2020 4:34 AM > >>>>>> To: Yingzhen Qu <[email protected]>; Peter Psenak > >>>>>> <[email protected]>; Gyan Mishra <[email protected]> > >>>>>> Cc: [email protected]; Jeff Tantsura <[email protected]> > >>>>>> Subject: Re: [Lsr] FW: New Version Notification for > >>>>>> draft-bonica-lsr-ip-flexalgo-00.txt > >>>>>> > >>>>>> Hi Yingzhen, > >>>>>> > >>>>>> IP Flexible Algorithms are like SR Flexible Algorithms in the > >>>>>> following > >>>> respects: > >>>>>> > >>>>>> - Links have IGP metrics, TE metrics, delay metrics and > >>>>>> administrative colors > >>>>>> - FADs define Flexible Algorithms > >>>>>> > >>>>>> More specifically, the FAD: > >>>>>> > >>>>>> - Indicates which metric type the Flexible Algorithm uses > >>>>>> - Specifies constraints in terms of link colors that are included > >>>>>> or excluded from the Flexible Algorithm. > >>>>>> > >>>>>> The significant difference between IP Flexible Algorithms and SR > >>>>>> Flexible Algorithms is: > >>>>>> > >>>>>> - SR Flexible Algorithms bind FADs to prefix SIDs or SRv6 locators > >>>>>> - IP Flexible Algorithms bind FADs to IPv4 or IPv6 addresses. > >>>>>> > >>>>>> So, IP Flexible Algorithms can be deployed in any IP network, even > >>>>>> in the absence of SR. > >>>>>> > >>>>>> Ron > >>>>>> > >>>>>> > >>>>>> Juniper Business Use Only > >>>>>> > >>>>>> -----Original Message----- > >>>>>> From: Yingzhen Qu <[email protected]> > >>>>>> Sent: Saturday, October 3, 2020 2:08 PM > >>>>>> To: Peter Psenak <[email protected]>; Gyan Mishra > >>>>>> <[email protected]>; Ron Bonica <[email protected]> > >>>>>> Cc: [email protected]; Jeff Tantsura <[email protected]> > >>>>>> Subject: Re: [Lsr] FW: New Version Notification for > >>>>>> draft-bonica-lsr-ip-flexalgo-00.txt > >>>>>> > >>>>>> [External Email. Be cautious of content] > >>>>>> > >>>>>> > >>>>>> Hi Peter, > >>>>>> > >>>>>> Using flex-algo, a SRv6 locator can be associated with a single > >>>>>> algo, which means an IPv6 or IPv4 address can also be associated > >>>>>> with a single algo. So my understanding is Ron's proposal is making > >>>>>> the > >>>> configuration of flex-algo easier? > >>>>>> Instead of using the exclude or include list you can configure a > >>>>>> loopback address to a flex-algo directly? > >>>>>> > >>>>>> Thanks, > >>>>>> Yingzhen > >>>>>> > >>>>>> On 10/3/20, 2:47 AM, "Peter Psenak" <[email protected]> wrote: > >>>>>> > >>>>>> Hi Yingzhen, > >>>>>> > >>>>>> On 02/10/2020 22:15, Yingzhen Qu wrote: > >>>>>> > Hi Peter, > >>>>>> > > >>>>>> > My understanding of flex-algo is that for traffic destined > >>>>>> to a prefix on a particular algo, it can only be routed on routers > >>>>>> belong to that algo, which also means only routers in that algo > >>>>>> calculates how to reach that prefix and install it into the routing > >>>>>> table. It seems to me that using flex-algo (section 12 of the > >>>>>> draft) it's possible to have a loopback address associated with > >>>>>> only one algo, please correct me if I'm missing or misunderstood > >> something. > >>>>>> > >>>>>> you are right. That is exactly what is being done for > flex-algo with > >>>>>> SRv6 - locator is associated with a single algo only. The > proposal > >> uses > >>>>>> the same concept. > >>>>>> > >>>>>> thanks, > >>>>>> Peter > >>>>>> > >>>>>> > > >>>>>> > Thanks, > >>>>>> > Yingzhen > >>>>>> > > >>>>>> > On 10/2/20, 9:43 AM, "Lsr on behalf of Peter Psenak" > >>>>>> <[email protected] on behalf of > >>>>>> [email protected]> > >>>>>> wrote: > >>>>>> > > >>>>>> > Gyan, > >>>>>> > > >>>>>> > On 02/10/2020 18:30, Gyan Mishra wrote: > >>>>>> > > All, > >>>>>> > > > >>>>>> > > With SRv6 and IP based flex algo a generic question > as it > >>>> applies > >>>>>> to > >>>>>> > > both. Is it possible to have within a single IGP > domain > >>>> different > >>>>>> sets > >>>>>> > > of nodes or segments of the network running > different > >>>>>> algorithms. > >>>>>> > > >>>>>> > absolutely. > >>>>>> > > >>>>>> > > From > >>>>>> > > both drafts it sounds like all nodes have to agree > on > >> same > >>>>>> algorithm > >>>>>> > > similar to concept of metric and reference bandwidth > >> all > >>>> have to > >>>>>> have > >>>>>> > > the same style metric and play to the same sheet of > >> music. > >>>>>> > > >>>>>> > all participating nodes need to agree on the > definition of > >> the > >>>>>> flex-algo > >>>>>> > and advertise the participation. That's it. > >>>>>> > > >>>>>> > > If there was > >>>>>> > > a way to use multiple algorithms simultaneously > based > >> on > >>>> SFC > >>>>>> or services > >>>>>> > > and instantiation of specific algorithm based on > service > >> to > >>>> be > >>>>>> > > rendered. Doing so without causing a routing loop > or > >> sub > >>>>>> optimal > >>>>>> > > routing. > >>>>>> > > >>>>>> > you can certainly use multiple algorithms > simultaneously > >> and > >>>> use > >>>>>> algo > >>>>>> > specific paths to forward specific traffic over it. > How that > >> is > >>>> done > >>>>>> > from the forwarding perspective depends in which > >>>> forwarding > >>>>>> plane you > >>>>>> > use. Flex-algo control plane is independent of the > >> forwarding > >>>>>> plane. > >>>>>> > > >>>>>> > > >>>>>> > >I thought with flex algo that there exists a feature > that > >> on > >>>>>> > > each hop there is a way to specify which algo to use > >> hop by > >>>> hop > >>>>>> similar > >>>>>> > > to a hop by hop policy based routing. > >>>>>> > > >>>>>> > no, there is no hop-by-hop classification, that is > >> problematic > >>>> and > >>>>>> does > >>>>>> > not scale for high speeds. Classification is done at > the > >>>> ingress only. > >>>>>> > > >>>>>> > thanks, > >>>>>> > Peter > >>>>>> > > >>>>>> > > > >>>>>> > > >>>>>> > > >> _______________________________________________ > >>>>>> > Lsr mailing list > >>>>>> > [email protected] > >>>>>> > > >>>>>> https://urldefense.com/v3/__https://nam11.safelinks.protection.outl > >>>>>> oo > >>>>>> k.com/ > >>>>>> ?url=https*3A*2F*2Fwww.ietf.org*2Fmailman*2Flistinfo*2Flsr&data > >>>>>> = > >>>> 0 > >>>>>> 2 > >>>>>> > >>>> > >> *7C01*7Cyingzhen.qu*40futurewei.com*7Cfe03124c6e414e067c2008d86781 > >>>>>> > >>>> > >> 6541*7C0fee8ff2a3b240189c753a1d5591fedc*7C1*7C0*7C63737315273986 > >>>>>> > >>>> > >> 5126&sdata=WI48cEAan*2FOkDPmVXGurEAjPItNGF9p9PDQIlD1ip0g*3D > >>>>>> > >>>> > >> &reserved=0__;JSUlJSUlJSUlJSUlJSUlJQ!!NEt6yMaO-gk!X1fRln9MjimeJcR > >>>>>> EUEIydr-8IIbtNonXMs83eoXvRww6xkaQfVUdNh0kK452GP-G$ > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > >>>>>> _______________________________________________ > >>>>>> Lsr mailing list > >>>>>> [email protected] > >>>>>> https://www.ietf.org/mailman/listinfo/lsr > >>>>> > >>>>> > >>>> > >>>> _______________________________________________ > >>>> Lsr mailing list > >>>> [email protected] > >>>> https://www.ietf.org/mailman/listinfo/lsr > >>> > >>> > >> > >> _______________________________________________ > >> Lsr mailing list > >> [email protected] > >> https://www.ietf.org/mailman/listinfo/lsr > > > > > > _______________________________________________ > Lsr mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/lsr >
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