Hi, Eduard,
> On Mar 23, 2021, at 8:47 AM, Vasilenko Eduard <[email protected]>
> wrote:
>
> Hi Joseph,
> Please, show any except (or section number) from any RFC that push vendor to
> use 1500B buffer for reassembly in the data plane on the transit node? (or
> any other number on the transit node)
The Internet defines:
- nodes that create or consume IP packets are hosts
- nodes that relay IP packets are routers
RFC1122/1123 summarizes host requirements. RFC1812 summarizes router
requirements. - both for IPv4. For IPv6, the former is largely in the IPv6 spec
RFC8200 and RFC8504 and the latter in RFC8200, though there are some useful
observations in RFC7084.
To your question, assuming you’re speaking of IPv6, RFC8200 requires nodes that
consume IPv6 packets to support 1500B reassembly.
RFC791 requires that nodes that consume IPv4 packets support 576B reassembly.
> Please, show any evidence (or just claim if you could not disclose) that any
> vendor has 1500B (or less) for reassembly in the data plane (on transit node).
I neither know nor care. That’s a compliance issue, not a standards issue.
> Please, show the evidence that the fragmentation problem exists.
This is described in detail in:
RFC1858
RFC4459
RFC4944
RFC6946
RFC6980
RFC7588
RFC8021
RFC8900
As well as nearly any tunnel protocol description.
> All your discussions for EMTU_R are not relevant – it is for *host*
> reassembly buffer.
See above; you need to understand that the Internet defines HOST as any device
that creates or consumes IP packets.
> Data Plane on the transit node has not been regulated before – It was not
> needed. Vendors have chosen big enough numbers that did not affect anybody so
> far.
See above; that’s not correct.
> It was effectively 1 MTU restriction per 1 virtual interface, not 2.
>
> I do not accept this:
> That’s just the case where pathMTU == EMTU_R.
> That means the EMTU_R is not needed *in practice*, but in principle it still
> exists.
> If particular tunneling technology does not have a reassembly buffer (reject
> fragmentation in principle) – we could not talk about it like it exists.
I don’t see why you’re stuck on this issue. You don’t have to implement a
separate reassembly buffer to have an implementation behave exactly as if there
was one with the same size as the pathMTU. The effect is the same - no
reassembly.
> If you would look to microcode – you would not find it. We could go very far
> with such logic.
I don’t take my cues from others’ implementations.
Joe
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