Re: [Int-area] 回复： Request a WG adoption call for draft-xu-intarea-ip-in-udp

[Tom Herbert <[e-mail]>]

On Thu, May 17, 2018 at 11:12 PM, 徐小虎(义先) <[e-mail]> wrote:
> Tom,
>
> It seems that your argument is based on an assumption that GUE is the only
> UDP tunnel mechanism implemented on the chip. What about if other UDP tunnel
> mechanisms (e.g., VXLAN, GENEVE and MPLS-in-UDP) are implemented as well?
>
Xiaohu,

Not at all. UDP encapsulation protocols are are discriminated by
looking at destination port number. After port number look up, they
are independent of one another.

Going back to your draft and specifically applicability of the
protocol, there is this text:

"This IP-in-UDP encapsulation causes E-IP [RFC5565] packets to be
forwarded across an I-IP [RFC5565] transit core via "UDP tunnels".
While performing IP-in-UDP encapsulation, an ingress AFBR (e.g.  PE
router) would generate an entropy value and encode it in the Source
Port field of the UDP header."

I have no idea what an E-IP, I-IP, AFBR, and PE router is. It looks
this is terminology buried deep in the Softwire RFC. The use of this
non-standard terminology and the reference to Softwire is abrupt in
the draft, there is no prior context given. Neither will you find this
in other specifications for UDP encapsulation. While the title and
abstract seem to imply that a general purpose encapsulation is being
defined, it's clear from the rest of the draft that there was a single
use case in mind when the draft was written (I guess Softwire). Not
only that, the protocol applicability described in the draft seems to
restrict use of the protocol precisely to that single use case. Either
the draft title and abstract should change, or the rest of the draft
should be generalized to match them.

In any case, even if the intent is to use the protocol for just for
the Softwire use case, I still don't think there's been a good answer
as to why the proposed protocol is required. Even if you don't like
GUE there are a number of other ways to encapsulate IP over UDP. Why
can't one of these be applied to the Softwire use case?

Tom

> Best regards,
> Xiaohu
>
> ------------------------------------------------------------------
> From:Tom Herbert <[e-mail]>
> Send Time:2018年5月18日(星期五) 09:52
> To:徐小虎(义先) <[e-mail]>
> Cc:Int-area <[e-mail]>; Joe Touch <[e-mail]>;
> [e-mail] <[e-mail]>; Internet Area <[e-mail]>
> Subject:Re: [Int-area] 回复： Request a WG adoption call for
> draft-xu-intarea-ip-in-udp
>
> On Thu, May 17, 2018 at 6:41 PM, 徐小虎(义先) <[e-mail]> wrote:
>> It's different. In GUE variant 1, the tunnel decapsulation device needs to
>> read the UDP destination port to determine that the UDP payload is a GUE
>> and
>> then to read the first two nibble of the GUE payload to determine whether
>> the UDP payload is actually an IP payload. It introduces an absolutely
>> unnecessary complexity in the procedure, especially for chips.
>>
> I don't follow. In SW this is a grand total of a single mask and
> conditional (maybe 3 assembly instructions). In HW this is nothing
> more than programming the TCAM with entries that match GUE v0, GUE v1
> IPv4, GUE v1 IPv6. Complexity of implementation is completely
> insignificant.
>
> Tom
>
>
>> Xiaohu
>>
>> ------------------------------------------------------------------
>> From:Templin (US), Fred L <[e-mail]>
>> Send Time:2018年5月18日(星期五) 09:28
>> To:Joe Touch <[e-mail]>; [e-mail] <[e-mail]>
>> Cc:Internet Area <[e-mail]>
>> Subject:Re: [Int-area] 回复： Request a WG adoption call for
>> draft-xu-intarea-ip-in-udp
>>
>>>Because it isn’t different. Again, see GUE variant 1.
>>
>>
>>
>> Correct. There is no reason to progress another draft that does the
>>
>> same thing as GUE variant 1.
>>
>>
>>
>> Fred
>>
>>
>>
>>
>>
>> From: Int-area [mailto:[e-mail]] On Behalf Of Joe Touch
>> Sent: Thursday, May 17, 2018 7:55 AM
>> To: [e-mail]
>> Cc: Internet Area <[e-mail]>
>> Subject: Re: [Int-area] 回复： Request a WG adoption call for
>> draft-xu-intarea-ip-in-udp
>>
>>
>>
>> Because it isn’t different. Again, see GUE variant 1.
>>
>>
>> On May 17, 2018, at 7:18 AM, Behcet Sarikaya <[e-mail]>
>> wrote:
>>
>>
>>
>>
>>
>> On Wed, May 16, 2018 at 10:22 PM, 徐小虎(义先) <[e-mail]>
>> wrote:
>>
>> It doesn't matter whether or not it's already there. IMHO, given the
>> popularity of different overlay technologies such as VXLAN and MPLS-in-UDP
>> in practice, GUE initially and mainly targeted as a DC overlay approach
>> has
>> little change to be widely deployed within data centers.
>>
>>
>>
>> As such, if the only possible applicability of GUE is for directly
>> carrying
>> IP over UDP, I don't understand why we need such a overhead associated
>> with
>> the variation of GUE. In another word, why not directly assign a port to
>> indicate IP-in-UDP, instead of using the GUE protocol variant number to
>> indicate. By the way, this the GUE protocol variant number usage reminds
>> me
>> of the notorious misuse of the first nibble of the MPLS payload to
>> indicate
>> the type of the MPLS payload:)
>>
>>
>>
>>
>>
>> I agree and support the adoption.
>>
>>
>>
>> I supported GUE in the past..
>>
>> Why not have another way of UDP encapsulation with the possibility of a
>> different area of applicability?
>>
>>
>>
>> Regards,
>>
>> Behcet
>>
>> Xiaohu
>>
>>
>>
>>
>>
>> ------------------------------------------------------------------
>>
>> From:Joe Touch <[e-mail]>
>>
>> Send Time:2018年5月16日(星期三) 15:45
>>
>> To:徐小虎(义先) <[e-mail]>
>>
>> Cc:Tom Herbert <[e-mail]>; Internet Area <[e-mail]>;
>> intarea-chairs <[e-mail]>; draft-xu-intarea-ip-in-udp
>> <[e-mail]>
>>
>> Subject:Re: [Int-area] 回复： Request a WG adoption call for
>> draft-xu-intarea-ip-in-udp
>>
>>
>>
>> It’s not complex. It’s already there. So there continues to be no reason
>> to
>> waste either a port number or further time discussing this draft.
>>
>>
>>
>> Joe
>>
>>
>> On May 15, 2018, at 9:01 PM, 徐小虎(义先) <[e-mail]> wrote:
>>
>> IMHO，there seems no need to introduce such complexity into GUE just for
>> the
>> purpose of saving one port number.
>>
>> Xiaohu
>>
>>
>>
>>
>> 来自钉钉专属商务邮箱
>>
>> ------------------------------------------------------------------
>> 发件人：Tom Herbert<[e-mail]>
>> 日 期：2018年05月16日 11:55:49
>> 收件人：徐小虎(义先)<[e-mail]>
>> 抄 送：Erik Kline<[e-mail]>; Internet Area<[e-mail]>;
>> draft-xu-intarea-ip-in-udp<[e-mail]>;
>> intarea-chairs<[e-mail]>
>> 主 题：Re: [Int-area] Request a WG adoption call for
>> draft-xu-intarea-ip-in-udp
>>
>> On Tue, May 15, 2018 at 8:33 PM, 徐小虎(义先) <[e-mail]>
>> wrote:
>>> Hi Eric,
>>>
>>> Good question. This draft (draft-xu-intarea-ip-in-udp) describes a native
>>> UDP encapsulation scheme for IP packets, which is straightforward and
>>> light-weighted, just as MPLS-in-UDP [RFC7510] and TRILL-in-UDP
>>> (https://tools.ietf.org/html/draft-ietf-trill-over-ip-16#page-20) and
>>> etc.
>>>
>> GUE variant 1 implements native UDP encapsulation for IPv4 and IPv6.
>> Except for a different port number, there is no protocol difference
>> between that and doing IP in UDP as separate protocol.
>>
>> Tom
>>
>>
>>> Best regards,
>>> Xiaohu
>>>
>>> ------------------------------------------------------------------
>>> From:Erik Kline <[e-mail]>
>>> Send Time:2018年5月16日(星期三) 11:07
>>> To:徐小虎(义先) <[e-mail]>
>>> Cc:intarea-chairs <[e-mail]>;
>>> draft-xu-intarea-ip-in-udp <[e-mail]>;
>>> Internet Area <[e-mail]>
>>> Subject:Re: [Int-area] Request a WG adoption call for
>>> draft-xu-intarea-ip-in-udp
>>>
>>> Should this document make some comment about its relation, or lack of
>>> relation, to https://tools.ietf.org/html/draft-ietf-intarea-gue ?
>>> On Wed, 16 May 2018 at 11:53, 徐小虎(义先) <[e-mail]>
>>> wrote:
>>>
>>>> Hi co-chairs,
>>>
>>>> We would like to request a WG adoption call for this draft (
>>> https://tools.ietf.org/html/draft-xu-intarea-ip-in-udp-07) since it has
>>> been stable enough and the solution as described in this draft is needed
>>> in
>>> practice.
>>>
>>>> Best regards,
>>>> Xiaohu (on behalf of all co-authors)
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>>>
>>>
>>>
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