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

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.

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

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*
> 
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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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