Stephane - I can imagine cases in which the per AF enabling might make sense (e.g. when the network associated w one address family is deemed non-critical).
Section 5.1 is a SHOULD - as is most of the document. It is therefore a suggestion as to what an implementation should provide. If a given implementer thinks this is either too onerous or not useful they can omit it w/o being in violation. But I see no reason to eliminate this - and in actual practice I would expect the cost of supporting such a knob to be low cost. It is hard for me to see this as controversial. Les From: [email protected] [mailto:[email protected]] Sent: Sunday, February 22, 2015 11:10 PM To: Les Ginsberg (ginsberg); Pushpasis Sarkar; Jeff Tantsura; [email protected] Subject: RE: LFA manageability : per AF config => feedback required [Les:] I think your point here is that the LFA calculation is AF independent within a given topology - but resources are consumed independent of how many computations are required- giving an operator the ability to determine which prefixes are most critical seems useful. That could be per AF or per prefix. [SLI] Agree but is the "resource saving" point strong enough to mandate per AF activation ? From: Les Ginsberg (ginsberg) [mailto:[email protected]] Sent: Monday, February 23, 2015 05:01 To: Pushpasis Sarkar; Jeff Tantsura; LITKOWSKI Stephane SCE/IBNF; [email protected]<mailto:[email protected]> Subject: RE: LFA manageability : per AF config => feedback required Pushpassis - From: rtgwg [mailto:[email protected]] On Behalf Of Pushpasis Sarkar Sent: Friday, February 20, 2015 3:28 AM To: Jeff Tantsura; [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]> Subject: Re: LFA manageability : per AF config => feedback required HI Jeff et al, I can think of a reason to have a knob per-level(or per-area) or per ISIS topology(note in ISIS a topology in ISIS always corresponds to a single AF,) [Les:] This is a common mistake to make. If one simply uses RFC 5308, then IPv6 prefixes can be advertised in the same topology as IPv4 (MTID #0) - and there are implementations which support this. More generally, from the protocol's POV a given topology can support any combinations of address families. It is only a convention because of the reserved MTIDs specified in RFC 5120 that certain MTIDs are "IPv6 only". But if one looks at the protocol capabilities such a restriction does not exist in general. Interestingly you contradicted yourself below. :) But I did want to set the record straight on this point - hopefully we are in agreement. and per realm and topology in OSPF. But I cannot think of a reason of why within the same topology we need another set of knobs for each AF. Here, by AF I understand IPV4 or IPv6. When both IPV4 and IPV6 are part of the same IGP topology, there is only one set of backup computations needed to protect both IPV4 and IPv6 traffic. Also I cannot think of any motivation for an operator to turn on protection on only one AF and does not want to turn on for the other even if both AFs has been deployed for normal forwarding. [Les:] I think your point here is that the LFA calculation is AF independent within a given topology - but resources are consumed independent of how many computations are required- giving an operator the ability to determine which prefixes are most critical seems useful. That could be per AF or per prefix. Les Thanks -Pushpasis From: Jeff Tantsura <[email protected]<mailto:[email protected]>> Date: Friday, February 20, 2015 at 12:59 PM To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>>, "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Subject: Re: LFA manageability : per AF config => feedback required Hi Stephane, /chair hat off IMO in disjoined topologies one should have flexibility to enable/disable LFA as per AF. Cheers, Jeff From: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Date: Thursday, February 19, 2015 at 11:21 PM To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Subject: LFA manageability : per AF config => feedback required Hi Folks, As you know, LFA manageability draft is in final phasis ... The current document states per AF granularity activation as a SHOULD. " 5.1<https://tools.ietf.org/html/draft-ietf-rtgwg-lfa-manageability-07#section-5.1>. LFA enabling/disabling scope The granularity of LFA activation should be controlled (as alternate nexthop consume memory in forwarding plane). An implementation of LFA SHOULD allow its activation with the following criteria: o Per address-family : ipv4 unicast, ipv6 unicast, LDP IPv4 unicast, LDP IPv6 unicast ... o Per routing context : VRF, virtual/logical router, global routing table, ... " In the framework of ISIS/OSPF yang modelization, we are challenging this statement, do we really need to force implementation to support this "per AF" granularity ? Please provide as soon as possible your feedback on this and also provide clear drivers to support or not per AF activation of LFA. Thanks for your help ! [Orange logo]<http://www.orange.com/> Stephane Litkowski Network Architect Orange/SCE/EQUANT/IBNF/ENDD/NDE Orange Expert Future Networks phone: +33 2 23 28 49 83 <https://monsi.sso.francetelecom.fr/index.asp?target=http%3A%2F%2Fclicvoice.sso.francetelecom.fr%2FClicvoiceV2%2FToolBar.do%3Faction%3Ddefault%26rootservice%3DSIGNATURE%26to%3D+33%202%2023%2028%2049%2083%20> mobile: +33 6 37 86 97 52 <https://monsi.sso.francetelecom.fr/index.asp?target=http%3A%2F%2Fclicvoice.sso.francetelecom.fr%2FClicvoiceV2%2FToolBar.do%3Faction%3Ddefault%26rootservice%3DSIGNATURE%26to%3D+33%206%2037%2086%2097%2052%20> [email protected]<mailto:[email protected]> _________________________________________________________________________________________________________________________ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. 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