Re: [Isis-wg] WG Adoption Call for draft-xu-isis-encapsulation-cap

[Hannes Gredler <[e-mail]>]

that sounds sufficient to me for tunnel end-point discovery;

/hannes

On 2/29/16 10:06, Xuxiaohu wrote:
> Hi Hannes and Les,
>
> The End Point sub-TLV as described in Section 5.3 is just used to indicate the tunnel endpoint address(es).
>
> Best regards,
> Xiaohu
>
>> -----Original Message-----
>> From: Isis-wg [mailto:[e-mail]] On Behalf Of Hannes Gredler
>> Sent: Monday, February 29, 2016 4:21 PM
>> To: Les Ginsberg (ginsberg)
>> Cc: [e-mail] list; Christian Hopps
>> Subject: Re: [Isis-wg] WG Adoption Call for draft-xu-isis-encapsulation-cap
>>
>> hi les,
>>
>> On 2/27/16 19:28, Les Ginsberg (ginsberg) wrote:
>>> Hannes -
>>>
>>> Discovery of tunnel endpoints is not what this draft is about.
>>>
>>> I am saying that I do not see that announcing tunnel capabilities is useful.
>> Discovering tunnel endpoints obviously is useful - as is identifying endpoint
>> addresses - but this draft will help us do neither.
>>
>> agreed - IP prefix info is missing ...
>> i can see two ways to fix this:
>>
>> 1. explicitly state that the tunnel-encaps-cap refers to a particular
>>      IP prefix
>> 2. move the tunnel-encaps-cap underneath an IP prefix TLV
>>
>> we should be good the, right ?
>>
>> /hannes
>>
>>>
>>>> -----Original Message-----
>>>> From: Hannes Gredler [mailto:[e-mail]]
>>>> Sent: Saturday, February 27, 2016 9:52 AM
>>>> To: Les Ginsberg (ginsberg)
>>>> Cc: Uma Chunduri; Christian Hopps; [e-mail] list
>>>> Subject: Re: [Isis-wg] WG Adoption Call for
>>>> draft-xu-isis-encapsulation-cap
>>>>
>>>> hi les,
>>>>
>>>> <wg-chair hat off>
>>>>
>>>> On Sat, Feb 27, 2016 at 05:18:39PM +0000, Les Ginsberg (ginsberg) wrote:
>>>> |    From my POV the draft currently defines how to advertise new
>>>> |    information without defining why it is necessary to do so.
>>>>
>>>> agree - "discovery of tunnel endpoints" should be explicitly spelled out.
>>>>
>>>> |
>>>> |    Yes, multiple tunnel types may be in use in the network - that does not
>>>> |    in and of itself lead to a requirement to advertise supported tunnel
>>>> |    types . In most cases, the support of a given tunnel type can be known
>>>> |    today by other means. You give the example of RLFA - but today LDP
>>>> |    reachability to an endpoint is something a router already knows - and
>>>> |    this is the real requirement to setup an RLFA tunnel. Knowing that the
>>>> |    endpoint is capable of supporting RLFA is insufficient. Further, folks
>>>> |    (including you if I recall correctly) have indicated that they want
>>>> |    more than just knowing RLFA capability - they also want to know what
>>>> |    endpoint address to use. This logically leads to the use of admin tags
>>>> |    which will not only indicate support for the tunnel type but also what
>>>> |    endpoint address is preferred/required.
>>>>
>>>> guess the RLFA example refers to non-MPLS (IP-only deployments)
>>>>
>>>> |    I think more thought and discussion is required before deciding that
>>>> |    this is something that should be supported. And I think this needs to
>>>> |    be done BEFORE this becomes a WG document as - almost without
>>>> exception
>>>> |    - anything that becomes a WG document proceeds to become an RFC.
>>>>
>>>> IMO the generic ability to discover tunnel-endpoints is something desireable.
>>>> agreed that the actual use-cases should be (better) documented
>>>> somewhere (perhaps in RTGWG ?), but we can do that after WG adoption
>>>> as well.
>>>>
>>>> - or is it that you want to make a case that discovery of tunnel
>>>> endpoints is not desired at all ?
>>>>
>>>> /hannes
>>>>
>>>> |    From: Uma Chunduri [mailto:[e-mail]]
>>>> |    Sent: Friday, February 26, 2016 12:09 PM
>>>> |    To: Uma Chunduri; Les Ginsberg (ginsberg); Christian Hopps;
>>>> |    [e-mail] list
>>>> |    Subject: RE: [Isis-wg] WG Adoption Call for
>>>> |    draft-xu-isis-encapsulation-cap
>>>> |
>>>> |
>>>> |    Dear Les et. al,
>>>> |
>>>> |
>>>> |    Please post any further comments you might have on this document.
>>>> |
>>>> |
>>>> |    --
>>>> |
>>>> |    Uma C.
>>>> |
>>>> |
>>>> |    From: Isis-wg [[1]mailto:[e-mail]] On Behalf Of Uma
>>>> |    Chunduri
>>>> |    Sent: Thursday, January 14, 2016 4:51 PM
>>>> |    To: Les Ginsberg (ginsberg); Christian Hopps; [2][e-mail] list
>>>> |    Subject: Re: [Isis-wg] WG Adoption Call for
>>>> |    draft-xu-isis-encapsulation-cap
>>>> |
>>>> |
>>>> |    Les,
>>>> |
>>>> |
>>>> |    Thanks for your comments, see in line [Uma]:
>>>> |
>>>> |    --
>>>> |
>>>> |    Uma C.
>>>> |
>>>> |
>>>> |    From: Isis-wg [[3]mailto:[e-mail]] On Behalf Of Les
>>>> |    Ginsberg (ginsberg)
>>>> |    Sent: Tuesday, January 12, 2016 5:25 PM
>>>> |    To: Christian Hopps; [4][e-mail] list
>>>> |    Subject: Re: [Isis-wg] WG Adoption Call for
>>>> |    draft-xu-isis-encapsulation-cap
>>>> |
>>>> |
>>>> |    Apologies for the very late response on this...
>>>> |
>>>> |
>>>> |    I have a couple of concerns regarding taking on this work.
>>>> |
>>>> |
>>>> |    The draft is straightforward enough in terms of the protocol extensions
>>>> |    defined, but I am not at all clear on the usefulness of the information
>>>> |    being advertised. The introduction to the draft discusses a variety of
>>>> |    tunnel types which might be used in a network but does not offer an y
>>>> |    reason why advertising the tunnel types supported is of benefit.
>>>> |
>>>> |
>>>> |    [Uma]: Lot of use cases have been described where there is no
>>>> |    configuration possible for all possible egress nodes at a given ingress
>>>> |    node; as asymmetric connections can be made dynamically based on
>> the
>>>> |    network topology; using the tunnel capabilities or parameters of egress
>>>> |    node  from ingress.
>>>> |
>>>> |
>>>> |    Given this information is only advertised within a single
>>>> |    administrative domain it does not seem to provide any information that
>>>> |    is not already known to the network operator.
>>>> |
>>>> |    [Uma]: This is not about whether network operators know all the
>>>> |    information but it's about if it is possible to configure/manage
>>>> |
>>>> |    a.       all options supported by possible egress nodes from ingress
>>>> |    nodes perspective or
>>>> |
>>>> |    b.      one option of all "possible" egress nodes from ingress nodes
>>>> |    pov.
>>>> |
>>>> |
>>>> |    It also logically leads to requiring a configuration for what tunnel
>>>> |    types to advertise. If this information is meant to drive automatic
>>>> |    configuration of tunnels I presume that the network operator would
>> want
>>>> |    to limit what is advertised - not simply accept what the implementation
>>>> |    is capable of supporting. So it seems we have simply traded one
>>>> |    configuration for another.
>>>> |
>>>> |    [Uma]: I don't see, we have traded any configuration here. An in-line
>>>> |    ingress application/feature  running as part of IS-IS ought to know
>>>> |    what kind of tunnel capabilities the egress node is capable of
>>>> |    accepting and associated parameters thereof for that tunnel.
>> Network
>>>> |    operator can always limit enabling  capabilities that are being
>>>> |    supported and capabilities that are being advertised by an egress node
>>>> |    as part of ISIS through configuration.
>>>> |
>>>> |
>>>> |    I would like to see more detail on this before deciding whether it is
>>>> |    worth doing.
>>>> |
>>>> |
>>>> |    It is clear that the information is not at all useful to IS-IS itself -
>>>> |    which brings me to my second concern. This is advertising information
>>>> |    that has nothing to with IS-IS. Router Capabilities is not meant to be
>>>> |    used as a vehicle to advertise information not of direct use to the
>>>> |    protocol.
>>>> |
>>>> |    [Uma]:  I am not sure why you see it is not all useful to IS-IS ; most
>>>> |    of the features/applications listed in  section 1 are related to  ISIS
>>>> |    protocols. For example RLFA- computation of PQ nodes done after
>>>> primary
>>>> |    SPF and as part of RLFA  SPFs (neighbor SPF, neighbors rSPF) and PQ
>>>> |    nodes are computed dynamically on the current topology. It's not
>>>> |    conceivable to provision an ingress node with one/all tunnel
>>>> |    capabilities of egress nodes (essentially where ever this feature is
>>>> |    enabled and potentially all eventually).  Similarly for Spring/Bier
>>>> |    nodes dynamic tunnels can be supported based on the neighboring
>>>> |    non-spring/non-bier node capabilities advertised.
>>>> |
>>>> |
>>>> |    In fact, the existence of a couple of exceptions to this guideline is
>>>> |    what prompted the creation of GENAPP (RFC 6823) as the appropriate
>>>> |    place to advertise such information.
>>>> |
>>>> |
>>>> |    I would like to see further discussion of the above before deciding
>>>> |    that WG adoption (which almost always indicates an intent to progress
>>>> |    to RFC) is appropriate.
>>>> |
>>>> |
>>>> |        Les
>>>> |
>>>> |
>>>> |
>>>> |    From: Isis-wg [[5]mailto:[e-mail]] On Behalf Of
>>>> |    Christian Hopps
>>>> |    Sent: Monday, November 30, 2015 11:45 PM
>>>> |    To: [6][e-mail] list
>>>> |    Subject: Re: [Isis-wg] WG Adoption Call for
>>>> |    draft-xu-isis-encapsulation-cap
>>>> |
>>>> |
>>>> |    [It seems due to some sneaky cut and paste error, the URL was wrong
>> in
>>>> |    the original email, I've corrected in this message]
>>>> |
>>>> |
>>>> |    Hi Folks,
>>>> |    The authors have requested the IS-IS WG adopt:
>>>> |
>>>> |
>>>> |
>>>> | [7]https://datatracker.ietf.org/doc/draft-xu-isis-encapsulation-cap
>>>> | /
>>>> |
>>>> |
>>>> |    as a working group document.
>>>> |
>>>> |    Please indicate support or no-support for taking on this work.
>>>> |    Thanks,
>>>> |    Chris.
>>>> |
>>>> | References
>>>> |
>>>> |    1. mailto:[e-mail]
>>>> |    2. mailto:[e-mail]
>>>> |    3. mailto:[e-mail]
>>>> |    4. mailto:[e-mail]
>>>> |    5. mailto:[e-mail]
>>>> |    6. mailto:[e-mail]
>>>> |    7.
>>>> | https://datatracker.ietf.org/doc/draft-xu-isis-encapsulation-cap/
>>>>
>>>> | _______________________________________________
>>>> | Isis-wg mailing list
>>>> | [e-mail]
>>>> | https://www.ietf.org/mailman/listinfo/isis-wg
>>>
>>
>> _______________________________________________
>> Isis-wg mailing list
>> [e-mail]
>> https://www.ietf.org/mailman/listinfo/isis-wg