Re: [v6ops] draft-smith-v6ops-larger-ipv6-loopback-prefix-04

[Mark Smith <[e-mail]>]

Hi Gyan,

On Wed, 28 Oct 2020, 09:10 Gyan Mishra, <[e-mail]> wrote:

> Hi Mark
>
> <snip>
>
>     Gyan> That is definitely an interesting idea and I think makes sense
> and viable for sure.  There maybe other use cases I am thinking out loud
> maybe with BIER IPv6  MVPN and possible some other use cases.  I wonder
> even for the SRv6 locator maybe having a special range outside of GUI
> allocation as it has special handling with steering.
>
> Another question related to IPv6 Anycast.  IPv6 has built in anycast
> address, I believe it’s the last 7 bits subnet router Anycast address.
> Since any routable prefix can be Anycasted for services proximity routing,
>  what is the real use case or functionality of the IPv6 built in Anycast
> /121 range.
>


There isn't really an IPv6 anycast range, IPv6 anycast addresses come out
of the unicast address space, and are only designated as anycast either by
announcing a "unicast" route from multiple different locations on purpose
(if it's not on purpose, it's a fault), and by configuring the host with
the anycast address to know that it is an anycast address.

I've thought that the use of Anycast would increase, and have thought that
it would be useful to have a specially designated anycast prefix. It has
also occurred to me that anycast has some of the properties of unicast as
well as some of the properties of multicast, so could be seen to fit in
between unicast and multicast (1:1 -> 1:Any -> 1:Many)

"IPv6 Formal Anycast and Functional Anycast Addresses"

IETF 106 presentation -
https://www.ietf.org/proceedings/106/slides/slides-106-6man-sessa-ipv6-formal-anycast-addresses-and-functional-anycast-addresses-00.pdf

Draft -
https://tools.ietf.org/html/draft-smith-6man-form-func-anycast-addresses-01

Regards,
Mark.





>
>> Regards,
>> Mark.
>>
>>
>>> Thanks
>>>
>>> Gyan
>>>
>>> On Mon, Oct 26, 2020 at 9:22 PM Mark Smith <[e-mail]>
>>> wrote:
>>>
>>>> Hi Gyan,
>>>>
>>>> Sorry not to get back to you sooner.
>>>>
>>>> On Tue, 20 Oct 2020 at 00:26, Gyan Mishra <[e-mail]>
>>>> wrote:
>>>> >
>>>> >
>>>> > Hi Mark
>>>> >
>>>> > What ended up happening with this draft
>>>>
>>>> I let it expire, as I didn't think it would be adopted by the WG.
>>>>
>>>> There seemed to be a bit of resistance to it as people said that ULAs
>>>> could be used instead.
>>>>
>>>> The link local prefix is also required on any IPv6 interface, per
>>>> RFC4291, so there is supposed to be a link-local /64 on the loopback
>>>> interface(s) providing many addresses to which a process could be
>>>> separately bound, although a drawback of using the link-local prefix
>>>> is having to deal with scope/zone IDs (although Linux doesn't comply
>>>> with that requirement, it doesn't have a link-local address on the
>>>> loopback interface by default).
>>>>
>>>> > and was the work picked up in any other draft.
>>>>
>>>> Not as far as I'm aware.
>>>>
>>>> What is your use case?
>>>>
>>>> Regards,
>>>> Mark.
>>>>
>>>>
>>>> >
>>>> > Thanks
>>>> >
>>>> > Gyan
>>>> >
>>>> > Sent from my iPhone
>>>>
>>> --
>>>
>>> <http://www.verizon.com/>
>>>
>>> *Gyan Mishra*
>>>
>>> *Network Solutions A**rchitect *
>>>
>>>
>>>
>>> *M 301 502-134713101 Columbia Pike
>>> <https://www.google.com/maps/search/13101+Columbia+Pike%C2%A0+Silver+Spring,+MD?entry=gmail&source=g>*Silver
>>> Spring, MD
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>>>
>>> --
>
> <http://www.verizon.com/>
>
> *Gyan Mishra*
>
> *Network Solutions A**rchitect *
>
>
>
> *M 301 502-134713101 Columbia Pike *Silver Spring, MD
>
>