Re: [spring] IPv4 EH proposal

[Alexandre Petrescu <[e-mail]>]

Le 07/09/2019 à 13:32, Robert Raszuk a écrit :
> /* Adjusting the subject to reflect the topic */
>
> Ok ... I looked at the new wave of mails in wrong order :)
>
> I like this proposal:
>
> https://tools.ietf.org/html/draft-herbert-ipv4-eh-01
>
> And have absolutely nothing against progressing it further - it looks 
> on the surface to be more efficient then sr-mpls over IP - but how 
> many bits are we saving needs to be calculated to state if cost of 
> introducing new encoding justifies the additional control plane, 
> protocol and platform efforts
>
> In fact if we would get to the consensus of using SRH with SID & BSID 
> to be of fixed 20 bits it can reuse a lot of mechanism build for 
> sr-mpls in any commercial router.
>
>  It is just a bit amazing that insertion of EHs into IPv4 would be 
> less problematic that in the case of IPv6 :) Maybe due to allowed 
> fragmentation.
>
> As to the host dropping packets due to unknown protocol - let's 
> observe that SR domain would clean such EH before passing packets 
> further.
>
> Many thx,
> R.

When I learned IPv4 existed it was already very late to suggest anything 
to it.  I learned that many things were designed into it at its origin, 
but few things got actually deployed.

The example of loose source route, and strict source route, was given as 
an example that people tried to do but it never worked at scale.  So it 
got filtered and disappeared.

I think now that any new such thing added beyond the simplest things in 
IP, like just destination and source, will be discarded later.

(even for IPv6, I struggle with Traffic Class vs Flow Label: where to 
put an emergency flag?  were it there to be just one field instead of 
two, my choice would be much easier.  The end user of this emergency 
flag asks this for 2 years now, and I still ponder over it, telling him 
to not worry and just send twice the emergency message.)

Alex


>
>
>
> On Sat, Sep 7, 2019 at 1:14 PM Mark Smith <[e-mail] 
> <mailto:[e-mail]>> wrote:
>
>     On Sat, 7 Sep 2019 at 19:56, Robert Raszuk <[e-mail]
>     <mailto:[e-mail]>> wrote:
>     >
>     > > It's tempting to write up SR over IPv4
>     >
>     > You don't have to write anything ... it is already written and
>     looks like moving fwd :)
>     >
>     > https://tools.ietf.org/html/draft-ietf-mpls-sr-over-ip-07
>     >
>
>     That's tunnelling MPLS over SR over IPv4. I'm talking about native SR
>     over IPv4 e.g. "SRv4".
>
>
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