Re: [Lsr] Seeking feedback to the revised draft-dunbar-lsr-5g-edge-compute

Gyan,

Your below email nicely proves my point. Unequal cost load sharing is done
at the app level not IGP transport.

Thank you,
R.

On Thu, Jan 13, 2022 at 2:26 AM Gyan Mishra <hayabusagsm@gmail.com> wrote:

>
> Robert
>
> Here are a few examples of UCMP drafts below used in core and data center
> use cases.
>
> https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-unequal-lb-15
>
> https://datatracker.ietf.org/doc/html/draft-mohanty-bess-weighted-hrw-02
>
> https://datatracker.ietf.org/doc/html/draft-ietf-idr-link-bandwidth
>
> https://datatracker.ietf.org/doc/html/draft-mohanty-bess-ebgp-dmz
>
>
>
> There are many use cases in routing for unequal cost load balancing
> capabilities.
>
> Kind Regards
>
> Gyan
>
> On Wed, Jan 12, 2022 at 2:23 PM Robert Raszuk <robert@raszuk.net> wrote:
>
>> Linda,
>>
>> > IGP has been used for the Multi-path computation for a long time
>>
>> IGP can and does ECMP well. Moreover, injecting metric of anycast server
>> destination plays no role in it as all paths would inherit that external to
>> the IGP cost.
>>
>> Unequal cost load balancing or intelligent traffic spread has always been
>> done at the application layer *for example MPLS*
>>
>> Thx a lot,
>> R.
>>
>> On Wed, Jan 12, 2022 at 8:18 PM Linda Dunbar <linda.dunbar@futurewei.com>
>> wrote:
>>
>>> Robert,
>>>
>>>
>>>
>>> Please see inline in green:
>>>
>>>
>>>
>>> *From:* Robert Raszuk <robert@raszuk.net>
>>> *Sent:* Wednesday, January 12, 2022 1:00 PM
>>> *To:* Linda Dunbar <linda.dunbar@futurewei.com>
>>> *Cc:* Les Ginsberg (ginsberg) <ginsberg@cisco.com>; lsr@ietf.org
>>> *Subject:* Re: [Lsr] Seeking feedback to the revised
>>> draft-dunbar-lsr-5g-edge-compute
>>>
>>>
>>>
>>> Hi Linda,
>>>
>>>
>>>
>>> *[LES:] It is my opinion that what you propose will not achieve your
>>> goals – in part because IGPs only influence forwarding on a per packet
>>> basis – not a per flow/connection basis.*
>>>
>>> *[Linda] Most vendors do support flow based ECMP, with Shortest Path
>>> computed by attributes advertised by IGP.*
>>>
>>>
>>>
>>> I am with Les here. ECMP has nothing to do with his point.
>>>
>>>
>>>
>>> [Linda] Les said that “IGP only influence forwarding on a per packet
>>> basis”.  I am saying that vendors supporting “forwarding per flow” with
>>> equal cost computed by IGP implies  that forwarding on modern routers are
>>> no longer purely per packet basis.
>>>
>>>
>>>
>>>
>>>
>>> Draft says:
>>>
>>>
>>>
>>> *When those multiple server instances share one IP address (ANYCAST),
>>> the transient network and load conditions can be incorporated in selecting
>>> an optimal path among server instances for UEs.*
>>>
>>>
>>>
>>> So if we apply any new metric to indicate load of a single anycast
>>> address how is this going to help anything ?
>>>
>>>
>>>
>>> [Linda] The “Load” or “Aggregated Site Cost” is to differentiate
>>> multiple paths with the same routing distance.
>>>
>>>
>>>
>>>
>>>
>>> You would need a mechanism where the network is smart and say per
>>> src-dst tuple or more spreads the traffic. IGP does not play that game
>>> today I am afraid.
>>>
>>> [Linda] There is one SRC and multiple paths to one DST. IGP has been
>>> used for the Multi-path computation for a long time.
>>>
>>>
>>>
>>> Thank you, Linda
>>>
>>>
>>>
>>> Thx a lot,
>>> R.
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>> _______________________________________________
>> Lsr mailing list
>> Lsr@ietf.org
>> https://www.ietf.org/mailman/listinfo/lsr
>>
> --
>
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>
> *Gyan Mishra*
>
> *Network Solutions A**rchitect *
>
> *Email gyan.s.mishra@verizon.com <gyan.s.mishra@verizon.com>*
>
>
>
> *M 301 502-1347*
>
>