Re: [pim] draft-ietf-pim-igmp-mld-extension WGLC

Thanks a lot for all the WGLC responses, in particular to Ian, Lenny,
Jeffrey and Jake for great comments. Hope I didn't miss anyone.

I just posted revision 03 that I think should address your comments.
Great if you can have a look. I realize I forgot to update the
acknowledgements though, so I will do that shortly.

Regards,
Stig

On Thu, Dec 17, 2020 at 3:25 PM Stig Venaas <stig@venaas.com> wrote:
>
> Hi Jeffrey
>
> I appreciate your comments, please see responses inline.
>
> On Tue, Dec 15, 2020 at 6:21 PM Jeffrey (Zhaohui) Zhang
> <zzhang=40juniper.net@dmarc.ietf.org> wrote:
> >
> > Support progressing this work.
> >
> >
> >
> > I have a couple of curiosity questions on the following:
> >
> >
> >
> >    Note that there may be additional data following this extension.  The
> >
> >    Total Extension Length field would indicate where this extension
> >
> >    ends, and the additional data starts.
> >
> >
> >
> > How would you have additional data following this extension? The TLV mechanism seems to be universal/generic to handle all possible extensions, so why would you have another extension blob after this, and how would you indicate so? By another bit in the reserved field?
> >
> > Just wondering if this additional data needs to be mentioned at all.
>
> I agree that there should be no need for additional data for future
> extensions as TLVs can provide any potential extension. If the WG and
> co-authors agree, I'm happy to remove the additional additional data.
> We can then also simplify the length check and say that the extension
> length specified must be equal to the remaining payload (subtracting
> from packet payload length).
>
> >
> >   Also, there is a possibility
> >
> >    that an implementation uses the Additional Data part of IGMP/MLD
> >
> >    messages, but not according to this extension scheme.
> >
> >
> >
> > Do you mean a non-standard existing implementation? Now that you mention that, are we supposed to define the interop procedures? Are they supposed to interop with the implementations following this draft at all?
>
> The IGMP/MLD RFCs specify how additional data may be present and how
> it should be ignored. I've seen cases where implementations
> intentionally (or maybe by accident) have sent packets with additional
> data. I think it is safest to use a reserved bit to clearly indicate
> that this extension is in place, rather than trying to parse whatever
> additional data may be present.
>
> If we receive data from an existing implementation, the reserved bit
> would not be set, and we would process it exactly as before.
> If an existing implementation receives the new IGMP/MLD message, it
> would both ignore the reserved bit, and the additional data according
> to the RFCs (although if implementations tried to use additional data
> in some way, then they might break, but I think we have to live with
> that). They were not supposed to use it.
>
> When using the extension, one must consider interoperability with
> implementations that do not support the extension mechanism, as well
> as implementations that do not support the specified types. Not
> supporting the mechanism, should be equivalent to not supporting any
> of the types.
>
> I can try to add a few more details in the draft.
> >
> >
> > Also, for the following:
> >
> >
> >
> >    The extension will be part of additional data as mentioned in
> >
> >    [RFC3810] Section 5.1.12 (resp.  [RFC3376] Section 4.1.10) for query
> >
> >    messages and [RFC3810] Section 5.2.12 (resp.  [RFC3376]
> >
> >    Section 4.2.11) for report messages.
> >
> >
> >
> > 5.2.12 should be 5.2.11.
>
> Good catch!
>
> Let me know if you have any thoughts on what I wrote above, or anything else.
>
> Thanks,
> Stig
>
> >
> >
> > Jeffrey
> >
> >
> >
> > From: pim <pim-bounces@ietf.org> On Behalf Of Michael McBride
> > Sent: Monday, December 7, 2020 7:24 PM
> > To: pim@ietf.org
> > Subject: [pim] draft-ietf-pim-igmp-mld-extension WGLC
> >
> >
> >
> > [External Email. Be cautious of content]
> >
> >
> >
> > Hello all,
> >
> >
> >
> > Today begins a two week wglc for https://tools.ietf.org/html/draft-ietf-pim-igmp-mld-extension-02
> >
> >
> >
> > Please review (it’s a quick read) and let us know your opinion on it’s readiness to progress to the iesg.
> >
> >
> >
> > Thanks,
> >
> > mike
> >
> >
> > Juniper Business Use Only
> >
> > _______________________________________________
> > pim mailing list
> > pim@ietf.org
> > https://www.ietf.org/mailman/listinfo/pim