Re: Embedding IP information in an IPv6 address (OMNI)

Bob Hinden <bob.hinden@gmail.com> Thu, 15 October 2020 18:43 UTC

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From: Bob Hinden <bob.hinden@gmail.com>
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Subject: Re: Embedding IP information in an IPv6 address (OMNI)
Date: Thu, 15 Oct 2020 11:43:12 -0700
In-Reply-To: <0191a92c5eb24aa3b74fd988852d1056@boeing.com>
Cc: Bob Hinden <bob.hinden@gmail.com>, =?utf-8?Q?Ole_Tr=C3=B8an?= <otroan@employees.org>, IPv6 List <ipv6@ietf.org>, "atn@ietf.org" <atn@ietf.org>
To: "Templin (US), Fred L" <Fred.L.Templin@boeing.com>
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Fred,

> On Oct 15, 2020, at 11:40 AM, Templin (US), Fred L <Fred.L.Templin@boeing.com> wrote:
> 
>>>>> 
>>>> 
>>>> The use of site locals also sets limitations of addressing/routing in the underlay.
>>> 
>>> This is rather about addressing/routing in the *overlay*.
>>> 
>>>> With regards to performance. Is the conversion between SLA/LLA something you do per packet?
>>>> If not, I'm unsure I see why optimising that is beneficial.
>>> 
>>> Per-packet - a simple bit-flip changes the address from SLA to LLA or vice-versa.
>> 
>> Umm, that would break the transport protocol checksum.
> 
> Good point, and that brings into focus the need for RFC2473 encapsulation.
> If you want a packet with IPv6 link-local addresses (LLAs) to go more than
> one hop, encapsulate it in an IPv6 header with the same LLAs and then
> flip the bit to turn them into SLAs. Then, present the (encapsulated) packet
> to the IPv6 overlay routing system.

If you want the packets to go more than one hop, then don’t use link-local addresses.

Bob