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

Tony Li <> Fri, 04 December 2020 00:13 UTC

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From: Tony Li <>
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Date: Thu, 3 Dec 2020 16:13:38 -0800
Cc: "Acee Lindem (acee)" <>, lsr <>
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To: Robert Raszuk <>
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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 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.