Regards
Lizhong
Lizhong
On 08/09/2016 22:33, Tom Herbert wrote:
On Mon, Aug 8, 2016 at 12:43 AM, Lizhong Jin <[email protected]> wrote:
> Hi,
> With my design experience of NIC and Switch, I prefer VXLAN-GPE. I have the
> same concern of HW complicated logic from Fabio, and additional concern to
> GENEVE and GUE is its long size of header.
> 1. GENEVE: 256+8=262Bytes
> 2. GUE: 128+4=132Bytes
This doesn't seem to take into account that NSH provides extensibility
for VXLAN-GPE as Fabio mentioned. If you were to take this into
account how does that affect HW complexity argument?
Lizhong: yes, if consider NSH as Fabio suggest, I need to rethink.
> In many current switch and NIC design, the parser buffer size is still
> 128Bytes, and some NIC/DMA has 256Bytes buffer. This is workable because:
> 1. IPv4 options is not widely used.
> 2. IPv6 extension header only support with limited number.
The limit of IPv6 extension headers is currently the maximum MTU of
the packet. Having no "small" limit is a problem for some hardware
that want to parse past them. There was a long discussion about this
in v6ops. One proposed idea to limit IPv6 extension headers to occupy
at most N bytes (N based on the parse buffer as you described). But
there was no agreement on what N should be, and it was pointed out
that not all implementations even have this problem and there is no
reason to believe HW won't continue to improve to make such an
artificial limit obsolete.
> But if adding GENEVE/GUE header, the minimum size of buffer is 256Bytes, or
> even 512Bytes. Then the question is, does the hardware need to process these
> Variable Length Options/Optional Fields/Private Data. If not, then it is not
> reasonable to force the hardware to increase the cost, but gain little.
>
Can you clarify this? If hardware does not need to process variable
length options then wouldn't that mean it does not need to support
them? This is in fact is the case with the many of NICs and switches
in deployment don't have protocol specific support for these
encapsulations. For such legacy HW we can leverage support for UDP
offloads (ECMP, RSS, checksum offload) to get really good solutions.
Hardware offloads of encapsulation protocols can be good optimization
(personally I am hoping we can offload DTLS for GUE), but I don't see
how HW support is a requirement nor how we are forcing hardware to
increase cost.
Lizhong: hardware will not recognize the variable length opinion, but it needs to skip these options, and to get inner packet header to do offloading, e.g., RSS as you mentioned. Then hardware surely needs to buffer the long header including variable length options. And we need to increase the parser buffer.
Thanks,
Tom
> Lizhong
>
>
>
>>
>> ---------- Forwarded message ----------
>> From: Alia Atlas <[email protected]>
>> To: NVO3 <[email protected]>
>> Cc: "Bocci, Matthew (Nokia - GB)" <[email protected]>
>> Date: Fri, 29 Jul 2016 11:13:00 -0400
>> Subject: Re: [nvo3] Consensus call on encap proposals
>> I'd like to have people focus on the key point of this thread.
>>
>> Are there serious technical objections (and specifically what are they) to
>> moving forward with VXLAN-GPE as the standards-track protocol?
>>
>> Are there serious technical objections (and specifically what are they) to
>> moving forward with GENEVE as the standards-track protocol?
>>
>> Are there serious technical objections (and specifically what are they) to
>> moving forward with GUE as the standards-track protocol?
>>
>> We need to capture any relevant objections. So far, there's been some
>> discussion on extensibility - with Tom Herbert providing concrete concerns.
>>
>> I have concluded that almost all the authors would prefer to have no
>> standards track solution if they can't guarantee that theirs is that
>> standard.
>>
>> I do hear concerns about whether a decision will be too late. I think
>> that a decision can only be helpful. It goes back to when is the best time
>> to plant a tree - with the answer of 20 years ago or now.
>>
>> Regards,
>> Alia
>>
>>
>> On Fri, Jul 29, 2016 at 4:34 AM, Naoki Matsuhira
>> <[email protected]> wrote:
>>>
>>>
>>>
>>> On 2016/07/21 23:56, Bocci, Matthew (Nokia - GB) wrote:
>>>>
>>>> WG
>>>>
>>>> There was a discussion in the NVO3 WG meeting in Berlin following strong
>>>> advice from our Area Director that we need to come to a consensus on
>>>> converging on a common encapsulation. Two sets of questions were asked:
>>>> (1) Should the WG move forward with one standards track encap?
>>>> (2) For a given encap, do you have significant technical objections?
>>>
>>>
>>> I want to inform to this mailing list that I proposed ME6E-FP and ME6E-PR
>>> at the yokohama meeting. I also have proposal M46E-FP and M46E-PR (past
>>> called SA46T).
>>>
>>> These encapsulation technologies are based on address mapping. ME6E use
>>> IPv6 address which mapping MAC address, and M46E use IPv6 address which
>>> mapping IPv4 address.
>>>
>>> I understand too many encapsulation technologies, however these my
>>> proposal are simple, and may contribute to the Internet.
>>>
>>> I believe address mapping approach is unique, so I want to propose again.
>>>
>>> sorry not the answer to the question.
>>>
>>> Naoki Matsuhira
>>>
>>>
>>> _______________________________________________
>>> nvo3 mailing list
>>> [email protected]
>>> https://www.ietf.org/mailman/listinfo/nvo3
>>
>>
>>
>
>
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