On 2/24/15, 11:00 AM, "Hannes Gredler" <[email protected]> wrote:

>On Tue, Feb 24, 2015 at 03:35:11PM +0000, Acee Lindem (acee) wrote:
>| Hannes - I don¹t see how you can jump to this conclusion - pretty lame
>;^)
>| Having the ability to enable or disable fast reroute protection by
>address
>| family by no means favors one address family over the other. There just
>| may be deployments where protection is just not desired for both and it
>is
>| not like it comes for free (since you must account for the topologies
>| being non-congruent).
>
>my point is that controlling LFA on a per-topology basis makes perfect
>sense.
>(as per your example above (non-congruent topologies), to save some
>number crunching).
>
>what does not make sense is: consider we've deployed IPv4/IPv6 in the
>default
>topology (integrated IS-IS model) - to turn off LFA for V6 routes.
>
>you have done already the number crunching, so why would you want
>to make IPv6 routes a second class citizen here ? -
>
>can you highlight the use-case here ?

One use case would be is that you are using IPv6 for business critical
services that require IP FRR protection. IPv4 is being used for in-band
network management and no protection is necessary.

Thanks,
Acee 






>
>/hannes
>
>| On 2/24/15, 10:03 AM, "Hannes Gredler" <[email protected]> wrote:
>| 
>| >HG> that IPv6 is less critical than IPv4 ? -
>| >    the IESG review will be a lot of fun then - i'll make some popcorn
>...
>| >
>| >On Mon, Feb 23, 2015 at 06:26:15PM +0000, Acee Lindem (acee) wrote:
>| >|    I agree with Les.
>| >|    Acee
>| >|    From: "Les Ginsberg (ginsberg)" <[1][email protected]>
>| >|    Date: Monday, February 23, 2015 at 10:55 AM
>| >|    To: Stephane Litkowski <[2][email protected]>,
>Pushpasis
>| >|    Sarkar <[3][email protected]>, Jeff Tantsura
>| >|    <[4][email protected]>, Routing WG <[5][email protected]>
>| >|    Subject: RE: LFA manageability : per AF config => feedback
>required
>| >| 
>| >|      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: [6][email protected]
>| >|      [[7]mailto:[email protected]]
>| >|      Sent: Sunday, February 22, 2015 11:10 PM
>| >|      To: Les Ginsberg (ginsberg); Pushpasis Sarkar; Jeff Tantsura;
>| >|      [8][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 ³resource saving² point strong enough to
>| >|      mandate per AF activation ?
>| >| 
>| >| 
>| >| 
>| >|      From: Les Ginsberg (ginsberg) [[9]mailto:[email protected]]
>| >|      Sent: Monday, February 23, 2015 05:01
>| >|      To: Pushpasis Sarkar; Jeff Tantsura; LITKOWSKI Stephane
>SCE/IBNF;
>| >|      [10][email protected]
>| >|      Subject: RE: LFA manageability : per AF config => feedback
>required
>| >| 
>| >| 
>| >| 
>| >|      Pushpassis -
>| >| 
>| >| 
>| >| 
>| >|      From: rtgwg [[11]mailto:[email protected]] On Behalf Of
>| >Pushpasis
>| >|      Sarkar
>| >|      Sent: Friday, February 20, 2015 3:28 AM
>| >|      To: Jeff Tantsura; [12][email protected];
>| >[13][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 protocol¹s 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
>³IPv6
>| >|      only². But if one looks at the protocol capabilities such a
>| >|      restriction does not exist in general.
>| >| 
>| >| 
>| >| 
>| >|      Interestingly you contradicted yourself below. J
>| >| 
>| >|      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 <[14][email protected]>
>| >|      Date: Friday, February 20, 2015 at 12:59 PM
>| >|      To: "[15][email protected]"
>| >|      <[16][email protected]>, "[17][email protected]"
>| >|      <[18][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: "[19][email protected]"
>| >|      <[20][email protected]>
>| >|      Date: Thursday, February 19, 2015 at 11:21 PM
>| >|      To: "[21][email protected]" <[22][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.
>| >| 
>| >|        ³
>| >| 
>| >|   [23]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, ...
>| >| 
>| >| 
>| >| 
>| >|        ³
>| >| 
>| >| 
>| >| 
>| >|        In the framework of ISIS/OSPF yang modelization, we are
>| >challenging
>| >|        this statement, do we really need to force implementation to
>| >support
>| >|        this ³per AF² 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 !
>| >| 
>| >| 
>| >| 
>| >| 
>| >| 
>| >|        [24]Orange logo
>| >| 
>| >| 
>| >| 
>| >|        Stephane Litkowski
>| >|        Network Architect
>| >|        Orange/SCE/EQUANT/IBNF/ENDD/NDE
>| >| 
>| >|        Orange Expert Future Networks
>| >| 
>| >|        phone: [25]+33 2 23 28 49 83
>| >|        mobile: [26]+33 6 37 86 97 52
>| >|        [27][email protected]
>| >| 
>| >| 
>| >| 
>| >| 
>| >| 
>| >|  
>| 
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>>_________________________________________________________________________
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>| >| References
>| >| 
>| >|    Visible links
>| >|    1. mailto:[email protected]
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>| >|    9. mailto:[email protected]
>| >|   10. mailto:[email protected]
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>| >|   23. 
>| 
>>https://tools.ietf.org/html/draft-ietf-rtgwg-lfa-manageability-07#section
>>-
>| >5.1
>| >|   24. http://www.orange.com/
>| >|   25. 
>| 
>>https://monsi.sso.francetelecom.fr/index.asp?target=http%3A%2F%2Fclicvoic
>>e
>| 
>>.sso.francetelecom.fr%2FClicvoiceV2%2FToolBar.do%3Faction%3Ddefault%26roo
>>t
>| >service%3DSIGNATURE%26to%3D+33%202%2023%2028%2049%2083%20
>| >|   26. 
>| 
>>https://monsi.sso.francetelecom.fr/index.asp?target=http%3A%2F%2Fclicvoic
>>e
>| 
>>.sso.francetelecom.fr%2FClicvoiceV2%2FToolBar.do%3Faction%3Ddefault%26roo
>>t
>| >service%3DSIGNATURE%26to%3D+33%206%2037%2086%2097%2052%20
>| >|   27. mailto:[email protected]
>| >
>| >
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