Subject: Modifiable Destination Options

From: Tom Herbert <[email-masked]>
Date: Thu, 28 Jun 2018 15:09:05 -0700

Hello,

I have a question about modifiable Destination Options.

RFC8200 states: "The third-highest-order bit of the Option Type
specifies whether or not the Option Data of that option can change en
route to the packet's final destination."

I don't see that that setting this bit for a Destination Option is
prohibited. So what is the effect of setting a Destination Option type
to be modifiable en route? Is setting a Destination Option to be
changeable en route valid? I suppose the text that extension headers
except for HBH can't be processed in transit implies that a DO can
never be modified en route and trumps the DO changeable bit, but are
there case where it could be legitimately be changed, maybe the end
host is allowed to modify the option before delivery to the
application?

Thanks,
Tom

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From: 神明達哉 <[email-masked]>
Date: Fri, 29 Jun 2018 09:54:23 -0700

At Thu, 28 Jun 2018 15:09:05 -0700,

> host is allowed to modify the option before delivery to the

When used with a routing header?

--
JINMEI, Tatuya

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From: Fernando Gont <[email-masked]>
Date: Fri, 29 Jun 2018 20:02:36 +0200

> host is allowed to modify the option before delivery to the

As far as IP is concerned, the destination *system* is the "end".

-- 
Fernando Gont
SI6 Networks
e-mail: [email-masked]
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492

---

From: Fred Baker <[email-masked]>
Date: Fri, 29 Jun 2018 14:37:47 -0700

> On Jun 29, 2018, at 9:54 AM, 神明達哉 <[email-masked]> wrote:
> 
>> to be modifiable en route?

I thought the point of a destination option was that it was only evaluated by the system identified by the destination address? If it's being modified in flight, that sounds like it belongs in the HBH header.

>> Is setting a Destination Option to be
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