Re: [Bier] Questions regarding <draft-zhang-bier-bierin6-03>

Greg Shepherd <gjshep@gmail.com> Tue, 16 July 2019 20:01 UTC

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References: <16253F7987E4F346823E305D08F9115AAB8DC468@nkgeml514-mbx.china.huawei.com> <DM5PR05MB3548E853C20E03CC58C7956BD4F10@DM5PR05MB3548.namprd05.prod.outlook.com> <MWHPR05MB32792FD6E09E4444B8DF45C3ACF30@MWHPR05MB3279.namprd05.prod.outlook.com> <16253F7987E4F346823E305D08F9115AAB8DD5B0@nkgeml514-mbx.china.huawei.com> <DM5PR05MB3548F4EFF3EFC0CCDA3FDE73D4F20@DM5PR05MB3548.namprd05.prod.outlook.com> <16253F7987E4F346823E305D08F9115AAB8DD87A@nkgeml514-mbx.china.huawei.com> <DM5PR05MB354819A911C930C1B8519CD4D4F20@DM5PR05MB3548.namprd05.prod.outlook.com> <DM5PR05MB3548637A9F8CBB1CB70BE3E6D4CD0@DM5PR05MB3548.namprd05.prod.outlook.com> <CAG9=0bJyYGhmLnm8CVk904EcouaW7VCP7KTvuciWc57NuiFDpQ@mail.gmail.com> <CA+wi2hNW4CbKgG1qgiaKqeGsz4GjS7hLkSDWH1yu4VFWfg2C5A@mail.gmail.com> <16253F7987E4F346823E305D08F9115AAB8EAFB1@nkgeml514-mbs.china.huawei.com> <CA+wi2hNZVEmUGBunc1YD5JAG7xtNnCf5hgzQ8FuSYOfJw2OcZg@mail.gmail.com> <16253F7987E4F346823E305D08F9115AAB8F1681@nkgeml514-mbs.china.huawei.com> <16253F7987E4F346823E305D08F9115AAB8F19ED@nkgeml514-mbs.china.huawei.com> <CA+wi2hM=xME5-nYCP1xkfMx7+SwSQUtSXqnywBaC9Vamx+rzEA@mail.gmail.com> <MN2PR13MB31500D98A77FBCCF7FC907C7F4CE0@MN2PR13MB3150.namprd13.prod.outlook.com>
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Reply-To: gjshep@gmail.com
From: Greg Shepherd <gjshep@gmail.com>
Date: Tue, 16 Jul 2019 13:00:54 -0700
Message-ID: <CABFReBroQ9085fu+nu383H9iii_J7n3gvNkd9N+43CFqJn0vsg@mail.gmail.com>
To: Michael McBride <michael.mcbride@futurewei.com>
Cc: Tony Przygienda <tonysietf@gmail.com>, Xiejingrong <xiejingrong@huawei.com>, BIER WG <bier@ietf.org>, "Jeffrey (Zhaohui) Zhang" <zzhang@juniper.net>, Senthil Dhanaraj <senthil.dhanaraj.ietf@gmail.com>, "draft-zhang-bier-bierin6@ietf.org" <draft-zhang-bier-bierin6@ietf.org>, Antoni Przygienda <prz@juniper.net>, "Jeffrey (Zhaohui) Zhang" <zzhang=40juniper.net@dmarc.ietf.org>
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Archived-At: <https://mailarchive.ietf.org/arch/msg/bier/8GiL4-GggTs0Xk1OtEfXKIcNrw0>
Subject: Re: [Bier] Questions regarding <draft-zhang-bier-bierin6-03>
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Thanks Mike. That's exactly what I had in mind. Take a look at the draft
agenda I just sent.

On Tue, Jul 16, 2019 at 12:17 PM Michael McBride <
michael.mcbride@futurewei.com> wrote:

> We better ask for a bit more time for bier-ipv6-requirements discussion
> then. Perhaps put it at the end again and we will use whatever time is
> available. I’ll lead it.
>
>
>
> Thanks,
>
> mike
>
>
>
> *From:* Tony Przygienda <tonysietf@gmail.com>
> *Sent:* Tuesday, July 16, 2019 8:29 AM
> *To:* Xiejingrong <xiejingrong@huawei.com>
> *Cc:* Jeffrey (Zhaohui) Zhang <zzhang@juniper.net>et>; Senthil Dhanaraj <
> senthil.dhanaraj.ietf@gmail.com>gt;; BIER WG <bier@ietf.org>rg>;
> draft-zhang-bier-bierin6@ietf.org; Antoni Przygienda <prz@juniper.net>et>;
> Jeffrey (Zhaohui) Zhang <zzhang=40juniper.net@dmarc.ietf.org>
> *Subject:* Re: [Bier] Questions regarding <draft-zhang-bier-bierin6-03>
>
>
>
> To close this thread the discussion needs to focus on the requirements
> draft during IETF and on this mailing list first and we see what comes out
> of that and accordingly the drafts will evolve ...
>
>
>
> I have many observations towards the req' draft and I expect a lively
> discussion. If I find time I may fire off something to the list before IETF
> along those lines ...
>
>
>
> thanks
>
>
>
> --- tony
>
>
>
> On Tue, Jul 16, 2019 at 3:31 AM Xiejingrong <xiejingrong@huawei.com>
> wrote:
>
> Sorry, the picture didn’t show in the list.
>
> I re-write in text:
>
>
>
> -------Solution Using NH=BIER (draft-zhang-bier-bierin6)-------
>
> Result = FIB Lookup(DA)                            //Step 0
>
> Switch(Result)
>
>   Case Local Interface IPv6 Address:               //Step 1
>
>     If packet is (NH=BIER)                         //Step 2 (*A*)
>
>         Process it
>
>     Else if packet is (NH=a/b/c/d & Last_NH=BIER)  //Step 3
>
>         Process it
>
>     Else If packet is (NH=XXXX)                    //Step 4 (*B*)
>
>         Process it
>
>     Else if packet is (NH=a/b/c/d & Last_NH=XXXX)  //Step 5
>
>         Process it
>
>     Else If packet is (NH=YYYY)                    //Step 6 (*C*)
>
>         Process it
>
>     Else if packet is (NH=a/b/c/d & Last_NH=YYYY)  //Step 7
>
>         Process it
>
>     Else
>
>         Do normal things as usual                  //Step 8 (*D*)
>
>   Case Non-Local Routable IPv6 Address
>
>       Do normal routing and forwarding as usual.
>
>
>
> (A) need 2~3 steps!
>
> (B) need 4~5 steps!
>
> (C) need 6~7 steps!
>
> (D) need 8 steps!
>
>
>
>
>
> -------Solution Using EH and
> End.BIER(draft-xie-bier-ipv6-encapsulation)-------
>
> Result = FIB Lookup(DA)                                   //Step 0
>
> Switch(Result)
>
>   Case End.BIER:                                          //Step 1
>
>     IF NH=60 and OptType1=BIER and OptLen1=HdrExtLen*8+4  //Step 2(A)
>
>          Process it
>
>     ELSE IF (NH=ICMPv6) or (NH=60 and Dest_NH=ICMPv6)
>
>          Send to CPU.
>
>     ELSE
>
>          Drop the packet.
>
>   Case End.XXXX:                                         //Step 1
>
>     IF NH=60 and OptType1=BIER and OptLen1=HdrExtLen*8+4 //Step 2(B)
>
>         Process it
>
>     ELSE
>
>         Drop the packet
>
>  Case End.YYYY:                                          //Step 1
>
>     IF NH=60 and OptType1=BIER and OptLen1=HdrExtLen*8+4 //Step 2(C)
>
>         Process it
>
>     ELSE
>
>         Drop the packet
>
>   Case Local Interface IPv6 Address:                     //Step 1
>
>         Do normal things as usual                        //Step 2(D)
>
>   Case Non-Local Routable IPv6 Address
>
>         Do normal routing and forwarding as usual.
>
>
>
> (A) need 2 steps!
>
> (B) need 2 steps!
>
> (C) need 2 steps!
>
> (D) need 2 steps!
>
>
>
>
>
> -------Repeat the advantages-------
>
> The least impact:  Switch-case by preceding FIB lookup doesn’t impact
> other cases.
>
> The most efficient:  Do not need walking through EH ---- only check the
> first EH.
>
> The most extensible to support features in the future:   Combine with
> Routing Header(e.g., SRH), Fragmentation, AH or ESP.  Support Multiple BIER
> TLVs in a single Destination Options header. etc.
>
>
>
> Thanks
>
> Jingrong.
>
>
>
> *From:* BIER [mailto:bier-bounces@ietf.org] *On Behalf Of *Xiejingrong
> *Sent:* Tuesday, July 16, 2019 5:29 PM
> *To:* Tony Przygienda <tonysietf@gmail.com>om>; Jeffrey (Zhaohui) Zhang <
> zzhang@juniper.net>
> *Cc:* Senthil Dhanaraj <senthil.dhanaraj.ietf@gmail.com>om>; BIER WG <
> bier@ietf.org>gt;; draft-zhang-bier-bierin6@ietf.org; Antoni Przygienda <
> prz@juniper.net>gt;; Jeffrey (Zhaohui) Zhang <zzhang=
> 40juniper.net@dmarc.ietf.org>
> *Subject:* Re: [Bier] Questions regarding <draft-zhang-bier-bierin6-03>
>
>
>
> Hi Tony, Jeffrey:
>
> Let’s f2f in BIER session at Montreal.
>
> Here is a page I think useful to understand the difference between Layer-4
> solution(left) and Layer-3 solution(right).
>
> That’s why I think use of a preceding End.BIER is most efficient (for BIER
> forwarding), least impact (to exist functions), and most extensible for
> future functions.
>
>
>
> The least impact:  Switch-case by preceding FIB lookup doesn’t impact
> other cases.
>
> The most efficient:  Do not need walking through EH ---- only check the
> first EH.
>
> The most extensible to support features in the future:   Combine with
> Routing Header(e.g., SRH), Fragmentation, AH or ESP.  Support Multiple BIER
> TLVs in a single Destination Options header. etc.
>
>
>
> Thanks
>
> Jingrong
>
>
>
> *From:* Tony Przygienda [mailto:tonysietf@gmail.com <tonysietf@gmail.com>]
>
> *Sent:* Monday, July 15, 2019 11:58 PM
> *To:* Xiejingrong <xiejingrong@huawei.com>
> *Cc:* Senthil Dhanaraj <senthil.dhanaraj.ietf@gmail.com>om>; Jeffrey
> (Zhaohui) Zhang <zzhang=40juniper.net@dmarc.ietf.org>rg>; BIER WG <
> bier@ietf.org>gt;; draft-zhang-bier-bierin6@ietf.org; Antoni Przygienda <
> prz@juniper.net>
> *Subject:* Re: [Bier] Questions regarding <draft-zhang-bier-bierin6-03>
>
>
>
>
>
>
>
> On Mon, Jul 15, 2019 at 12:39 AM Xiejingrong <xiejingrong@huawei.com>
> wrote:
>
> Please see my comments below:
>
>
>
> *From:* Tony Przygienda [mailto:tonysietf@gmail.com]
> *Sent:* Monday, July 15, 2019 3:04 PM
> *To:* Senthil Dhanaraj <senthil.dhanaraj.ietf@gmail.com>
> *Cc:* Jeffrey (Zhaohui) Zhang <zzhang=40juniper.net@dmarc.ietf.org>rg>;
> Xiejingrong <xiejingrong@huawei.com>om>; BIER WG <bier@ietf.org>rg>;
> draft-zhang-bier-bierin6@ietf.org; Antoni Przygienda <prz@juniper.net>
> *Subject:* Re: [Bier] Questions regarding <draft-zhang-bier-bierin6-03>
>
>
>
> if your router can do BIER fast path IPv6 is not an interesting option no
> matter which draft.
>
> [XJR] That’s not true. The interest in BIER-IPv6-fast-path is strong.
> There is no problem of “interest” or “requirement”. The problem is the lack
> of convinced  “technology” or “solution”.
>
>
>
> enlighten me where you saw that except being personally convinced it's
> cool ... And what is the specific reason customer would want that
> complexity/cost of v6 option processing silicon compared to ether/mpls
> encaps.
>
>
>
> one would either carry native ether or MPLS rather than trying to build
> IPv6 fast path with header options @ arbitrary place,
>
> probably misaligning bitmasks and ultimately forcing 4K buffers on v6
> option processing in silicon which may be fun but it is expensive, complex
> fun.
>
> [XJR] The proposals are not as good as expected,  or could not do it in a
> simple and inexpensive way! I guess this is the point.
>
>
>
> yupp. MPLS/Ether will be as inexpensive as it can be and shares same
> processing block.
>
>
>
> [XJR] Well I think, using a preceding BIER-Specific IPv6 Address in IPv6
> DA can solve the problem perfectly.
>
> [XJR] This is the way SRv6/SRH do, *which first introduces the fast-path
> processing of extension header*, without recognition the pattern of the
> EHs and the TLVs, but simply ‘process the desired packet, and drop the
> undesired packet’!
>
>
>
> BIER is neither SRv6 nor SRH so your point here is?
>
>
>
> BIER is a L2.5 hop-by-hop multicast switching technology that should be
> tunneled otherwise. v6 enaps (where we really abuse v6 as L1 transport) is
> only justified if ether/mpls cannot be implemented but chips can do very
> simple v6 processing and there is not high throughput requirement (albeit
> one could build bierin6 fast-path in silicon obviously). Obviously bierin6
> gives you the nice trick to tunnel it to a v6 destination without
> establishing a real tunnel but it's really just a by-product and not its
> main goal
>
>
>
> --- tony
>
>
>
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