Re: [mpls] Poll for WG adoption for draft-pac-mpls-lsp-ping-tlvs-and-sub-tlvs-registry-02

Mach,

But if you make this change, then you have the opposite problem, because
you also have TLVs that don't inherit the sub-TLVs from type 1, so you need
some way of saying exactly which sub-TLVs apply to those. And you could
easily create new sub-TLVs that don't apply to TLV 1, 16, or 21.

A better solution to me is to list the sub-TLVs for TLV 1 just as it is
now, and for TLV 21, use the exact same note that's in the table for TLV 16
("NOTE: all current and future sub-TLVs for Target FEC Stack also apply to
this TLV"). In addition, for TLV 21, if there's an RFC that creates a new
sub-TLV that is ONLY for TLV 21, in that RFC the instructions for IANA are
to create a new sub-TLV (say 26) for TLV 21, and at the same time, allocate
sub-TLV 26 of TLV 1 as "Reserved for TLV 21 use, unused for TLV 1".

Cheers,
Andy

On Wed, May 15, 2013 at 11:35 PM, Mach Chen <mach.chen@huawei.com> wrote:

>  Hi Andy,****
>
> ** **
>
> The current “TLVs and sub-TLVs” structure works very well if specific
> sub-TLVs only belong to a single TLV. But with increasing of TLVs and
> sub-TLVs, there are more and more TLVs trying to share sub-TLVs defined for
> other TLV. For example, Type 16 TLV is designed to reuse all existing and
> future sub-TLVs defined for Type 1 TLV. Type 21 TLV is also intended to
> apply all the existing and future defined sub-TLVs of Type 1 TLV, and at
> the same time, it also defines its own dedicated sub-TLVs, it’s difficult
> or even impossible to achieve this with the current “TLV and sub-TLVs”
> allocation rules and policies. Since if one TLV wants to inherit/reuse all
> sub-TLVs of one TLV, they actually share the same name space, there is no
> safe way to define TLV dedicated sub-TLVs. ****
>
> ** **
>
> For example, Type 1 TLV has defined 25 sub-TLVs so far, it will define
> more in the future, Type 21 TLV applies these sub-TLVs for itself; then
> Type 21 TLV wants to define its own sub-TLV, what code points should be
> allocated to the sub-TLV?  If allocating 26 to it, then when Type 1 TLV
> defines one more new sub-TLV, it will probably be allocated 26 as the code
> point, then confliction occurs. And even if you allocate a much bigger
> number (e.g., 1000) to the new sub-TLV, in theory, the confliction cannot
> be avoided completely. ****
>
> ** **
>
> The required changes proposed in the draft will not impact the
> implementation, it just changes the way on how to register a sub-TLV. ****
>
> ** **
>
> In addition, the similar definition/usage is not novel, for example, the
> Attribute Flag TLV can be carried/shared in/by many Objects, but flags are
> defined and register in a common space.****
>
> ** **
>
> There are a lot of discussions online/offline about the TLV and sub-TLVs
> allocations rules and policies on progressing the draft-ietf-mpls
> -return-path-specified-lsp-ping,  and the draft is still stuck by this
> allocation issue. Seems this is the best solution that we could think of so
> far.  ****
>
> ** **
>
> Best regards,****
>
> Mach****
>
> ** **
>
> *From:* mpls-bounces@ietf.org [mailto:mpls-bounces@ietf.org] *On Behalf
> Of *Andrew G. Malis
> *Sent:* Thursday, May 16, 2013 5:51 AM
> *To:* George Swallow (swallow)
> *Cc:* Ross Callon; mpls@ietf.org; mpls-chairs@tools.ietf.org;
> draft-pac-mpls-lsp-ping-tlvs-and-sub-tlvs-registry@tools.ietf.org
> *Subject:* Re: [mpls] Poll for WG adoption for
> draft-pac-mpls-lsp-ping-tlvs-and-sub-tlvs-registry-02****
>
> ** **
>
> I agree with George from a definition standpoint, I don't find the "TLVs
> and sub-TLVs" table at
> http://www.iana.org/assignments/mpls-lsp-ping-parameters/mpls-lsp-ping-parameters.xmldifficult to follow at all. However, it would be interesting to hear from
> implementers if they've had any difficulty implementing the TLVs and
> sub-TLVs.****
>
> But at this point, with existing implementations, I think we need a REALLY
> GOOD reason to change other than some people find the table confusing,
> which seems to be the main justification in the draft.****
>
> ** **
>
> Also, if the draft is adopted, it would be useful for it to have a link to
> the IANA page in the references.
>
> Cheers,****
>
> Andy****
>
> ** **
>
> On Tue, May 14, 2013 at 11:26 AM, George Swallow (swallow) <
> swallow@cisco.com> wrote:****
>
> With hat off.****
>
> ** **
>
> No/do not support.****
>
> ** **
>
> I believe that making a single sub-TLV space is going to lead to a lot of
> confusion in the future as to which sub-TLVs are used with which TLVs.
>  That is one will have to search through bunch of documents instead of
> seeing it clearly laid out in the registry.  ****
>
> ** **
>
> Keeping the spaces separate for RSVP has worked well.  I really don't get
> what is preventing that here.  ****
>
> ** **
>
> George****
>
> ** **
>
> *From: *Ross Callon <rcallon@juniper.net>
> *Date: *Sunday, May 5, 2013 10:53 PM
> *To: *"mpls@ietf.org" <mpls@ietf.org>, "
> draft-pac-mpls-lsp-ping-tlvs-and-sub-tlvs-registry@tools.ietf.org" <
> draft-pac-mpls-lsp-ping-tlvs-and-sub-tlvs-registry@tools.ietf.org>
> *Cc: *"mpls-chairs@tools.ietf.org" <mpls-chairs@tools.ietf.org>****
>
>
> *Subject: *[mpls] Poll for WG adoption for
> draft-pac-mpls-lsp-ping-tlvs-and-sub-tlvs-registry-02****
>
> ** **
>
> Working group,****
>
>  ****
>
> this is to start a "two week" poll on adopting****
>
> draft-pac-mpls-lsp-ping-tlvs-and-sub-tlvs-registry-02****
>
> as an MPLS working group document.****
>
>  ****
>
> Please send your comments (support/not support) to the mpls working****
>
> group mailing list (mpls@ietf.org).****
>
>  ****
>
> This poll will end May 20th, 2013.****
>
>  ****
>
> Ross****
>
> (as mpls wg co-chair)****
>
>  ****
>
>  ****
>
>
> _______________________________________________
> mpls mailing list
> mpls@ietf.org
> https://www.ietf.org/mailman/listinfo/mpls****
>
> ** **
>