Re: [Bier] BIER in IPv6 --- draft-zhang-bier-bierin6-04

On Tue, 24 Mar 2020, 06:43 Brian E Carpenter, <brian.e.carpenter@gmail.com>
wrote:

> Hi Xuesong,
>
> >  link-local forwarding concerns
>
> What are those concerns? Link-local forwarding is forbidden by RFC4291 and
> any router that performs it is completely faulty and should be thrown away.
>

Actually, forwarding is allowed by RFC 4007, but only back onto the same
link.

> For the BIER scenario, link-local seems very suitable.
>

Sounds like I'd agree, just haven't read the ID.

Packets with ULA or GUA DAs and LL SAs have been seen to leak off link.
Those implementations a missing an RPF like check on LL SAs. The sending
hosts shouldn't really be sending those packets in the first place.

There's always a risk of bugs or non-compliant implementations, which is
why Postel's law exists.

(Wouldn't it be great if a "Implementations MUST be bug free." statement in
an RFC was complied with 100%!)

Regards,
Mark.

> Regards
>    Brian Carpenter
>
> On 23-Mar-20 19:27, Gengxuesong (Geng Xuesong) wrote:
> > Hi,
> >
> >
> >
> > Thank you for your prompt response, and giving your considerations about
> these two methods.
> >
> > I notice that you mentioned:
> >
> >>>this has a nice side effect of allowing to "jump over non-BIER routers"
> if addressed to bier prefix
> >
> > So would this method be the preferred one to cover more scenarios ?
> >
> > It seems to me that 2 different methods may need more technical
> considerations for both of them, such as , link-local forwarding concerns
> for option 1 and global-address security concerns for option 2.
> >
> >
> >
> > Best Regards
> >
> > Xuesong
> >
> >
> >
> > *From:*Tony Przygienda [mailto:tonysietf@gmail.com]
> > *Sent:* Monday, March 23, 2020 11:21 AM
> > *To:* zhang.zheng <zhang.zheng@zte.com.cn>
> > *Cc:* Gengxuesong (Geng Xuesong) <gengxuesong@huawei.com>; 6MAN <
> 6man@ietf.org>; BIER WG <bier@ietf.org>
> > *Subject:* Re: BIER in IPv6 --- draft-zhang-bier-bierin6-04
> >
> >
> >
> > That's a currently ongoing discussions between the auhtors (cc:'ing bier
> as well)
> >
> >
> >
> > LL has advantages
> >
> > * the packet cannot "escape" even if it has TTL > 1
> >
> > * such a scheme can work purely with ND
> >
> > * it's hard to "send out the wrong interface" albeit v6 allows AFAIR to
> have same link local on multiple interfaces
> >
> >
> >
> > Originally the draft did not even allow for global addressing (since we
> want to use v6 as L2-substitute here just like MPLS & non-MPLS
> encapsulations are used in BIER) but this has a nice side effect of
> allowing to "jump over non-BIER routers" if addressed to bier prefix (which
> I personally think should be the only allowed global v6 used, otherwise we
> may end up with BIER frames in funky places and possible "holes" in the
> replication fabric). Obviously strictly speaking it's not necessary since
> BIER can be carried in plethora of normal unicast tunnels  but bunch of
> co-auhtors joined and the consensus was to allow it
> >
> >
> >
> > --- tony
> >
> >
> >
> >
> >
> >
> >
> > On Sun, Mar 22, 2020 at 8:15 PM <zhang.zheng@zte.com.cn <mailto:
> zhang.zheng@zte.com.cn>> wrote:
> >
> >     Hi Xuesong,
> >
> >
> >
> >     Thank you for your question!
> >
> >     The LL address is used by direct connected neighbor.
> >
> >     For the neighbor which is not direct connected, the wider range
> address should be used.
> >
> >
> >
> >     Thanks,
> >
> >     Sandy
> >
> >
> >
> >     原始邮件
> >
> >     *发件人：*Gengxuesong(GengXuesong) <gengxuesong@huawei.com <mailto:
> gengxuesong@huawei.com>>
> >
> >     *收件人：*张征00007940;6man@ietf.org <mailto:6man@ietf.org> <6man@ietf.org
> <mailto:6man@ietf.org>>;
> >
> >     *日 期 ：*2020年03月23日11:03
> >
> >     *主 题 ：RE: Re:BIER in IPv6 --- draft-zhang-bier-bierin6-04*
> >
> >     Hi Sandy and authors of draft-zhang-bier-bierin6:
> >
> >
> >
> >     I have some questions about the section 2 when reading the draft. It
> is mentioned that:
> >
> >     “If... The destination address in IPv6 header SHOULD be the
> neighbor's link-local address.
> >
> >     Otherwise... the destination address SHOULD be the BIER prefix of
> the BFR neighbor.”
> >
> >     Seems like the draft proposes 2 methods of IPv6 header encapsulation.
> >
> >     Could these 2 methods be combined ? If not, what's the use case and
> design consideration for each method?
> >
> >
> >
> >     Best Regards
> >
> >     Xuesong
> >
> >
> >
> >
> >
> >
> >
> >     *From:*ipv6 [mailto:ipv6-bounces@ietf.org <mailto:
> ipv6-bounces@ietf.org>]*On Behalf Of *zhang.zheng@zte.com.cn <mailto:
> zhang.zheng@zte.com.cn>
> >     *Sent:* Saturday, March 21, 2020 1:43 PM
> >     *To:* 6man@ietf.org <mailto:6man@ietf.org>
> >     *Subject:* Re:BIER in IPv6 --- draft-zhang-bier-bierin6-04
> >
> >
> >
> >     Hi,
> >
> >     As co-author of BIERin6 (draft-zhang-bier-bierin6-04), before you
> read the draft, please let me introduce BIER technology to you at first:
> >
> >     BIER technology, as defined in RFC8279, it's a new multicast
> technology. The principle is achieving multicast forwarding by hop-by-hop
> execution.
> >
> >     BIER is a transport protocol, not just a function. As defined in
> RFC8296, BIER has it's own ethernet encapsulation with ethernet type
> 0xAB37, and also it can be travelled by MPLS encapsulation.
> >
> >     BIER has it's own OAM function, ECMP function and traceability. etc.
> through BIER header defined in RFC8296.
> >
> >
> >
> >     For travelling through IPv6 only enviroment, we'd like to travel
> BIER packet by IPv6 encapsulation.
> >
> >     In draft-zhang-bier-bierin6-04, we want to just use a new Next
> Header type for BIER header carrying.
> >
> >     We want to bring the minimum impact on IPv6 existed execution, and
> the maximum flexibility for header interoperability.
> >
> >     So if you have any question about draft-zhang-bier-bierin6-04, or
> about BIER technology itself, please tell me. I'am glad to explain them to
> you.
> >
> >
> >
> >     Thanks,
> >
> >     Sandy
> >
> >
> >
> >     原始邮件
> >
> >     *发件人：*TonyPrzygienda <tonysietf@gmail.com <mailto:
> tonysietf@gmail.com>>
> >
> >     *收件人：*Michael McBride <michael.mcbride@futurewei.com <mailto:
> michael.mcbride@futurewei.com>>;
> >
> >     *抄送人：*6man@ietf.org <mailto:6man@ietf.org> <6man@ietf.org <mailto:
> 6man@ietf.org>>;
> >
> >     *日 期 ：*2020年03月19日01:12
> >
> >     *主 题 ：Re: BIER in IPv6*
> >
> >     --------------------------------------------------------------------
> >     IETF IPv6 working group mailing list
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> >
> >     <BIER WG chair hat on>
> >
> >
> >
> >     The specific ask here is for the 6man to look over both drafts, i.e.
> >
> >
> >
> >     draft-zhang-bier-bierin6
> >
> >
> >
> >     and
> >
> >
> >
> >     draft-xie-bier-ipv6-encapsulation
> >
> >
> >
> >     and verify whether they conform to published IPv6 standards or raise
> objections/concerns.
> >
> >
> >
> >     The requirements document is currently under active work/comments
> and does not represent any final or wide-consensus state so an opinion on
> its state is appreciated but it should not be used as any final or binding
> list of requirements as to the targeted solution in BIER WG
> >
> >
> >
> >     thanks
> >
> >
> >
> >     --- tony
> >
> >
> >
> >     On Tue, Mar 17, 2020 at 9:20 PM Michael McBride <
> michael.mcbride@futurewei.com <mailto:michael.mcbride@futurewei.com>>
> wrote:
> >
> >         Hello,
> >
> >
> >
> >         The bier wg could use your ipv6 recommendations. We’ve worked on
> various solutions to transport a bier header in ipv6. We decided to pause
> and create a requirements document (draft-ietf-bier-ipv6-requirements) to
> help steer us towards the right solution(s). In that drafts appendix we
> have a fairly good summary of the various solutions.
> >
> >
> >
> >         We’ve started to rally behind two solutions which meet the
> majority of the requirements: draft-xie-bier-ipv6-encapsulation (bier
> header in ipv6 EH) and draft-zhang-bier-bierin6 (bier header as payload
> using ipv6 NH). The bier chairs today asked to punt the bierv6 topic to
> 6man for advice before adopting any of these solutions.
> >
> >
> >
> >         So here we are seeking your advice. The most simple approach
> would probably be to give
> https://datatracker.ietf.org/doc/draft-ietf-bier-ipv6-requirements/ a
> look and scroll down to the appendix to see a summary of the various
> solutions we’ve been considering.
> >
> >
> >
> >         thanks!
> >
> >         mike
> >
> >
> >
> >
> >
> >
> >
> >
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