Re: [Lsr] FW: New Version Notification for draft-bonica-lsr-ip-flexalgo-00.txt

["Dongjie (Jimmy)" <[e-mail]>]

Hi Jeff,

Thanks for your explanation. I understand that for different data plane the SIDs or IP addresses have different scope, and will not conflict in normal cases.

My question is more about whether a computation node needs to know and check which data plane is used by the intermediate nodes to bind to the Flex-Algo? In another word, can an SR path computed using Flex-Algo 128 go through an intermediate node which bind Flex-Algo 128 to IP data plane?

Best regards,
Jie

> -----Original Message-----
> From: Jeff Tantsura [mailto:[e-mail]]
> Sent: Sunday, October 11, 2020 3:14 AM
> To: Ron Bonica <[e-mail]>
> Cc: Dongjie (Jimmy) <[e-mail]>; Peter Psenak
> <[e-mail]>; Yingzhen Qu <[e-mail]>; Gyan
> Mishra <[e-mail]>; [e-mail]
> Subject: Re: [Lsr] FW: New Version Notification for
> draft-bonica-lsr-ip-flexalgo-00.txt
> 
> Jie,
> 
> The scoop is different, for SR data plane entry uniqueness is in context of SR
> domain (SID = value + context), while for IP it is global to the routing domain,
> FIB entry is a destination, nothing more.
> 
> Regards,
> Jeff
> 
> > On Oct 10, 2020, at 05:47, Ron Bonica <[e-mail]> wrote:
> >
> > Hi Jimmie,
> >
> > Inline.....
> >
> >                    Ron
> >
> >
> > Juniper Business Use Only
> >
> > -----Original Message-----
> > From: Dongjie (Jimmy) <[e-mail]>
> > Sent: Friday, October 9, 2020 11:06 PM
> > To: Peter Psenak <[e-mail]>; Ron Bonica
> > <[e-mail]>; Yingzhen Qu <[e-mail]>; Gyan
> > Mishra <[e-mail]>
> > Cc: [e-mail]; Jeff Tantsura <[e-mail]>
> > Subject: RE: [Lsr] FW: New Version Notification for
> > draft-bonica-lsr-ip-flexalgo-00.txt
> >
> > [External Email. Be cautious of content]
> >
> >
> > 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?
> >
> > [RB] I never thought about this. Is there a use-case? I think that it will work,
> but I would have to try it before saying for sure.
> >
> > 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. 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?
> >
> > [RB] I don't think so. However, you could achieve the same outcome using link
> colors.
> >
> > If so, how could this node know the binding of FA to different data planes on
> other nodes?
> >
> > Best regards,
> > Jie
> >
> >> -----Original Message-----
> >> From: Lsr [mailto:[e-mail]] On Behalf Of Peter Psenak
> >> Sent: Friday, October 9, 2020 11:58 PM
> >> To: Dongjie (Jimmy) <[e-mail]>; Ron Bonica
> >> <rbonica=[e-mail]>; Yingzhen Qu
> >> <[e-mail]>; Gyan Mishra <[e-mail]>
> >> Cc: [e-mail]; Jeff Tantsura <[e-mail]>
> >> 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:[e-mail]] On Behalf Of Ron Bonica
> >>>> Sent: Sunday, October 4, 2020 4:34 AM
> >>>> To: Yingzhen Qu <[e-mail]>; Peter Psenak
> >>>> <[e-mail]>; Gyan Mishra <[e-mail]>
> >>>> Cc: [e-mail]; Jeff Tantsura <[e-mail]>
> >>>> 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 <[e-mail]>
> >>>> Sent: Saturday, October 3, 2020 2:08 PM
> >>>> To: Peter Psenak <[e-mail]>; Gyan Mishra
> >>>> <[e-mail]>; Ron Bonica <[e-mail]>
> >>>> Cc: [e-mail]; Jeff Tantsura <[e-mail]>
> >>>> 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" <[e-mail]> 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"
> >>>> <[e-mail] on behalf of
> >>>> ppsenak=[e-mail]>
> >>>> 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
> >>>>>
> >>>>>>
> >>>>>
> >>>>>     _______________________________________________
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