Re: [Lsr] WG Adoption Call for "IGP Flexible Algorithms (Flex-Algorithm) In IP Networks" - draft-bonica-lsr-ip-flexalgo-01

Robert Raszuk <robert@raszuk.net> Fri, 04 December 2020 00:24 UTC

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From: Robert Raszuk <robert@raszuk.net>
Date: Fri, 4 Dec 2020 01:24:44 +0100
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To: Tony Li <tony1athome@gmail.com>
Cc: "Acee Lindem (acee)" <acee=40cisco.com@dmarc.ietf.org>, lsr <lsr@ietf.org>
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Subject: Re: [Lsr] WG Adoption Call for "IGP Flexible Algorithms (Flex-Algorithm) In IP Networks" - draft-bonica-lsr-ip-flexalgo-01
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Hi Tony,

The moment I hit "Send" I knew that this response may be coming as it
really depends what is one's definition of TE.

If indeed IGP TE is anything more then SPF - then sure we can call it a TE
feature.

However, while a very useful and really cool proposal, my point is to make
sure this is not oversold - that's all.

Best,
R.


On Fri, Dec 4, 2020 at 1:13 AM Tony Li <tony1athome@gmail.com> wrote:

>
> Hi Robert,
>
>
> > However I really do not think that what Flexible Algorithm offers can be
> compared or even called as Traffic Engineering (MPLS or SR).
> >
> > Sure Flex Algo can accomplish in a very elegant way with little cost
> multi topology routing but this is not full TE. It can also direct traffic
> based on static or dynamic network preferences (link colors, rtt drops etc
> ... ),  but again it is not taking into account load of the entire network
> and IMHO has no way of accomplish TE level traffic distribution.
> >
> > Just to make sure the message here is proper.
>
>
> It’s absolutely true that FlexAlgo (IP or SR) has limitations. There’s no
> bandwidth reservation. There’s no dynamic load balancing. No, it’s not a
> drop in replacement for RSVP. No, it does not supplant SR-TE and a good
> controller. Etc., etc., etc….
>
> However I don’t feel that it’s fair to say that FlexAlgo can’t be called
> Traffic Engineering.  After all TE is a very broad topic. Everything that
> we’ve done that’s more sophisticated than simple SPF falls in the area of
> Traffic Engineering.  Link coloring and SRLG alone clearly fall into that
> bucket.
>
> I’ll grant you that it may not have the right TE features for your
> application, but that doesn’t mean that it’s not sufficient for some.
> Please don’t mislead people by saying that it’s not Traffic Engineering.
>
> Regards,
> Tony
>
>
>