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

Ho Ron,

On 10/10/2020 14:47, Ron Bonica wrote:
> Hi Jimmie,
> 
> Inline.....
> 
>                      Ron
> 
> 
> Juniper Business Use Only
> 
> -----Original Message-----
> From: Dongjie (Jimmy) <jie.dong@huawei.com>
> Sent: Friday, October 9, 2020 11:06 PM
> To: Peter Psenak <ppsenak@cisco.com>; Ron Bonica <rbonica@juniper.net>; Yingzhen Qu <yingzhen.qu@futurewei.com>; Gyan Mishra <hayabusagsm@gmail.com>
> Cc: lsr@ietf.org; Jeff Tantsura <jefftant.ietf@gmail.com>
> 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.

yes, this works fine.

> 
> 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.

please see my response to the Jimmy.

thanks,
Peter

> 
> 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:lsr-bounces@ietf.org] On Behalf Of Peter Psenak
>> Sent: Friday, October 9, 2020 11:58 PM
>> To: Dongjie (Jimmy) <jie.dong@huawei.com>; Ron Bonica
>> <rbonica=40juniper.net@dmarc.ietf.org>; Yingzhen Qu
>> <yingzhen.qu@futurewei.com>; Gyan Mishra <hayabusagsm@gmail.com>
>> Cc: lsr@ietf.org; Jeff Tantsura <jefftant.ietf@gmail.com>
>> 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:lsr-bounces@ietf.org] On Behalf Of Ron Bonica
>>>> Sent: Sunday, October 4, 2020 4:34 AM
>>>> To: Yingzhen Qu <yingzhen.qu@futurewei.com>; Peter Psenak
>>>> <ppsenak@cisco.com>; Gyan Mishra <hayabusagsm@gmail.com>
>>>> Cc: lsr@ietf.org; Jeff Tantsura <jefftant.ietf@gmail.com>
>>>> 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 <yingzhen.qu@futurewei.com>
>>>> Sent: Saturday, October 3, 2020 2:08 PM
>>>> To: Peter Psenak <ppsenak@cisco.com>; Gyan Mishra
>>>> <hayabusagsm@gmail.com>; Ron Bonica <rbonica@juniper.net>
>>>> Cc: lsr@ietf.org; Jeff Tantsura <jefftant.ietf@gmail.com>
>>>> 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" <ppsenak@cisco.com> 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"
>>>> <lsr-bounces@ietf.org on behalf of
>>>> ppsenak=40cisco.com@dmarc.ietf.org>
>>>> 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
>>>>       >      Lsr@ietf.org
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