Hi Peter, > -----Original Message----- > From: Peter Psenak [mailto:[email protected]] > Sent: Wednesday, December 9, 2020 6:45 PM > To: Dongjie (Jimmy) <[email protected]>; Acee Lindem (acee) > <[email protected]>; lsr <[email protected]> > Subject: Re: [Lsr] WG Adoption Call for "IGP Flexible Algorithms > (Flex-Algorithm) In IP Networks" - draft-bonica-lsr-ip-flexalgo-01 > > Jimmy, > > On 09/12/2020 11:10, Dongjie (Jimmy) wrote: > > Hi authors, > > > > Here is one comment following the previous discussion on the mail list > > and the IETF meeting. > > > > The IP Algorithm TLV is defined to advertise the IP Flex-Algorithm > > participation information, there is no separate TLV for IPv4 or IPv6 > > Flex-Algo participation. > > the draft clearly says: > > "The IP Flex-Algorithm participation advertised in ISIS IP Algorithm > Sub-TLV is topology independent."
This does not answer my question. Section 7 gives the rules of IP Flex-Algo Path calculation: " IP Flex-Algorithm application only considers participating nodes during the Flex-Algorithm calculation. When computing paths for a given Flex-Algorithm, all nodes that do not advertise participation for IP Flex-Algorithm, as described in Section 5, MUST be pruned from the topology. " >From IP Algorithm TLV, one cannot tell whether a node participates in >Flex-Algo 128 for IPv4, IPv6 or both. This would cause the problem described >below: When one node uses IP Flex-Algo participation to compute a path for an IPv6 address advertised with Flex-Algo 128, it will not prune the nodes which participate in Flex-Algo 128 for IPv4 only from the topology. Thus IPv6 packets following that path may get dropped on nodes which participates in Flex-Algo 128 for IPv4 only. > > > If some nodes participate in IPv4 Flex-Algo 128, and some of these > > nodes participate in IPv6 Flex-Algo 128, how to ensure that the path > > computed for IPv6 Flex-Algo will not use the nodes which only > > participate in IPv4 Flex-Algo 128? > > there is no such thing as "IPv4 Flex-Algo 128" or "IPv6 Flex-Algo 128". > There is only algo 128. Agree that Flex-Algo 128 is application or data plane agnostic, and as we discussed the same Flex-Algo can be used with both IPv4 and IPv6 (maybe also for SR-MPLS, SRv6). These terms are used as shorthand of "Flex-Algo 128 used with IPv4 or IPv6" > You are mixing data plane support with algo participation. I understand Flex-Algo definition is application agnostic, and Flex-Algo participation is application specific, it is just not clear to me whether IPv4 and IPv6 can be treated as one application. > If you want an algo to only include nodes that supports specific data plane, > you would need to define a specific algo for it. This IMO contradicts with the base concept: Flex-Algo definition is application (or data plane) agnostic. Best regards, Jie > > thanks, > Peter > > > > > > Best regards, > > > > Jie > > > > *From:*Lsr [mailto:[email protected]] *On Behalf Of *Acee Lindem > > (acee) > > *Sent:* Wednesday, December 2, 2020 5:13 AM > > *To:* lsr <[email protected]> > > *Subject:* [Lsr] WG Adoption Call for "IGP Flexible Algorithms > > (Flex-Algorithm) In IP Networks" - draft-bonica-lsr-ip-flexalgo-01 > > > > This IP Flex Algorithm draft generated quite a bit of discussion on > > use cases and deployment prior to IETF 109 and there was generally > > support for WG adoption. This begins a two week WG adoption call. > > Please indicate your support or objection to WG adoption on this list > > prior to > > 12:00 AM UTC on December 16^th , 2020. Also, review comments are > > certainly welcome. > > > > Thanks, > > > > Acee > > _______________________________________________ Lsr mailing list [email protected] https://www.ietf.org/mailman/listinfo/lsr
