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

Hi Jimmy.

On 12/10/2020 09:12, Dongjie (Jimmy) wrote:
> 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?

computation node MUST check the application specific participation in 
flex-algo and participation advertisement is application specific. SR 
and IP are different applications from flex-algo perspective.

draft-ietf-lsr-flex-algo-12, section 10.2:

    Application-specific advertisement for Flex-Algorithm participation
    MUST be defined for each application

thanks,
Peter

> 
> Best regards,
> Jie
> 
>> -----Original Message-----
>> From: Jeff Tantsura [mailto:jefftant.ietf@gmail.com]
>> Sent: Sunday, October 11, 2020 3:14 AM
>> To: Ron Bonica <rbonica@juniper.net>
>> Cc: Dongjie (Jimmy) <jie.dong@huawei.com>; Peter Psenak
>> <ppsenak@cisco.com>; Yingzhen Qu <yingzhen.qu@futurewei.com>; Gyan
>> Mishra <hayabusagsm@gmail.com>; lsr@ietf.org
>> 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 <rbonica@juniper.net> 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.
>>>
>>> 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: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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> 
> 