Re: [Int-area] 答复: 答复: 答复: 答复: Is the UDP destination port number resource running out?// re: I-D Action: draft-ietf-intarea-gue-04.txt

[Joe Touch <[e-mail]>]

On 5/25/2017 1:40 PM, Tom Herbert wrote:
> On Thu, May 25, 2017 at 12:44 PM, Templin, Fred L
> <[e-mail]> wrote:
>> If you are talking about the GUE direct encapsulation of IPv4 and IPv6, I
>> agree
>>
>> with the current spec and that direct encapsulation (i.e., with no
>> additional
>>
>> encapsulations between the IP/UDP and inner IP headers) is desirable and
>>
>> should remain as part of the spec. I think we may be over-thinking this.
>>
> +1. I think a little too much has been inferred beyond the what is
> actually in draft. Versions are straightforward:
>
> - There is a two bit version number field that begins GUE header. The
> format of the rest of the header depends on the version.
> - Version 0 defines an encapsulation header that encapsulates by IP
> protocol number.
> - Version 1 defined a means for direct encapsulation of select
> protocols as an optimization. Formats for IPv4 and IPv6 are defined.
> - Version 2 and 3 are reserved
I continue to be confused as to why it is more useful to try to make
decisions based on the first two bits rather than the first four.
There's near zero benefit, and the harm is that you end up with only two
reserved versions.

>
> Rather Version 1 constitutes a new version or a different format seems
> to be a matter of terminology, however semantically and implementation
> wise the intent is clear. If it's necessary the field could be renamed
> "version/format"
It is not a version; I think that's at least part of the problem. It's a
type or kind, but version implies that V0 is superceded by V1, which may
or may not be backward compatible with V0.

Joe