Re: [mpls] Available IP version numbers.

[Haoyu Song <[e-mail]>]

-----Original Message-----
From: Toerless Eckert <[e-mail]> 
Sent: Monday, April 19, 2021 3:32 PM
To: Haoyu Song <[e-mail]>
Cc: Loa Andersson <[e-mail]>; mpls <[e-mail]>
Subject: Re: [mpls] Available IP version numbers.

On Mon, Apr 19, 2021 at 04:29:13PM +0000, Haoyu Song wrote:
> I'm not so worried about the IP version exhaustion. We can always use the similar method as that used by MPLS to extend the SPLs.

Could be IMHO more efficient encoded than it was possible in MPLS.
First four bits = IPv10(10), nex four bits reserved for extension versions.

[HS] This is what I mean. When you run out of special values, you just use a special value to indicate that after it is the new and extended field of special values. 

> What I'm thinking is that in the future, perhaps in addition to the major version number, we should also have minor version numbers to allow gradual evolution of the protocol.

What do you think is the most likely reason for requiring a mayor and/or minor version number ?
I can't come up wih a good example.

[HS] With this, we can support minor innovations in a major version without needing a new version number each time, or to support experimental and incremental updates to the current version, which do not deserve a new version number.

Cheers
    Toerless

> 
> Haoyu
> 
> -----Original Message-----
> From: mpls <[e-mail]> On Behalf Of Toerless Eckert
> Sent: Saturday, April 17, 2021 1:46 PM
> To: Loa Andersson <[e-mail]>
> Cc: mpls <[e-mail]>
> Subject: Re: [mpls] Available IP version numbers.
> 
> a) Any more insight into the reserved numbers ?
>    If there are failed experiments (i think there might have been ?)
>    That would be good to review to avoid similar errors.
> 
> b) I would not be concerned about exhaustion if we come up with one proposal
>    that gives us good confidence of extensibility. 
> 
> c) Any backward compatibility reason for us not being able to use 8
>    bits - out of which the first 4 bits of course can only use unassigned
>    values.
> 
> Cheers
>     Toerless
> 
> On Sat, Apr 17, 2021 at 04:13:23PM +0800, Loa Andersson wrote:
> > DT,
> > 
> > We had a discussion on how many IP version numbers are available. 
> > 
> > It should be remembered that in IANA ???Reserved??? really means ???Reserved, do not assign???. 
> > 
> > 0,1,5,7,8,9 and 15 are reserved. 
> > 2,3,10,11,12,13 and 14 are unassigned
> > 4 and 6 are assigned 
> > 
> > To make the reserved requires a standard track RFC. 
> > 
> > So we 7 IP version numbers available, that is a sufficient low number to make me nervous, if I owned the registry. 
> > 
> > I would nit count on having more IP version numbers assigned to ???us???, especially since we already have an agreement (PWE3), accepting to get two numbers and committing to not use more. 
> > 
> > /Loa
> > 
> > Sent from my iPhone
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