[lacnog] Question about 240/4 space

Mie Jul 24 17:40:53 -03 2019

Hi Fernando,

I’ll be answering in Spanish if that is not a problem.

Es una muy buena pregunta. Resumiendo, el espacio IPv4 240.0.0.0/4 está marcado en los registros de IANA como “Uso Futuro”. Esta asignación surge de la Sección 4 de la RFC 1112 (https://tools.ietf.org/html/rfc1112 <https://tools.ietf.org/html/rfc1112>). La pregunta es… ¿no podemos re-designar estos 16 /8s como espacio unicast y asignarlos, dado que son tan necesarios?

Es una pregunta muy válida. La RFC 1112 data de 1989, una fecha que parece hoy casi prehistórica. La Internet en 1989 era una red pequeña, limitada a organizaciones de gobierno, universidades, etc.

Yo tengo mi posición personal, y no estoy convencido de que valga la pena. No porque “vaya a demorar el despliegue de IPv6”, sino por otra razón. Este espacio de direcciones, si lo comenzamos a asignar, va a ser un espacio de direccionamiento de calidad inferior.

¿Porque?

Para poder utilizar 240/4 como espacio unicast hace falta que los fabricantes de equipamiento *todos* actualicen su software y en sus stacks permitan que paquetes en este rango de direcciones sea procesado como unicast. Estoy hoy no es así. 

Ahora bien, no alcanza solo con que los fabricantes actualicen su software. TODOS nosotros operadores desde microscópicos a gigantes tenemos que actualizer los softwares y firmwares de TODO nuestro equipamiento para que estos paquetes en la 240/4 sean tratados de igual manera que digamos, los de la 179/8. Todo equipo que hable IP producido en los últimos 30 años va a tener que ser actualizado.

Nuestro historial como industria implementando estos cambios en escala es muy malo. Hasta el día de hoy hay firewalls que descartan paquetes UDP de DNS de mas de 512 bytes (EDNS0 data de 2013), stacks que implementan IPv6 mal, routers que no soportan ciertos elementos de BGP, etc.

Lo que va a pasar es que eventualmente comencemos a asignar espacio de la 240/8, quienes reciban espacio van a tener un servicio de calidad muy muy inferior. Van a tener errores de conexión y timeouts muy difíciles de depurar. Van a tener problemas con sus clientes. Van a tener problemas en conseguir tránsito y peering que soporte esto. 

Por este motivo fundamentalmente, no estoy de acuerdo con la propuesta. Sin embargo, la discusión está abierta en el IETF y serán todos más que bienvenidos en enviar sus comentarios a las listas de correo relevantes. 

Saludos,

/Carlos

> On Jul 24, 2019, at 4:16 PM, Fernando Frediani <fhfrediani en gmail.com> wrote:
> 
> Hello folks
> 
> I wanted to put a question about this topic in order to learn a bit deeper into this question from the community who have better knowledge about it, specially those who have more IETF involvement.
> 
> The last time I asked why still the 240/4 wasn't turned into usable /8's to be distributed to all RIRs and therefore to LIRs and End-users. The explanation I was given at the time was that people considered it for quiet a while and came to a conclusion that was not worth the cost of 'changing everything needed to be changed' in order to make it work as expected. Some have mentioned that some network firmware had embedded in it to not even forward packets in this IP space.
> On this basis I wanted also to understand also who was the 'clever' idea to deny forwarding to this packets in firmware to something tagged as "Future Use", therefore that had the expectation to be used one day in the future ?
> 
> I am asking this because I have been reading some 'yet again' proposals to make it viable and wanted to understand what are the the biggest technical challenges to make it viable.
> If it is true that some firmware have this limitation, and it goes down to a CPE level I can start understanding the amount of work to get every single equipment updated to be able to talk to these future networks. Even in a ISP/Telecom level one thing that comes to mind is where you have very old and EOF routers still in production and people refusing to take them our of production, no doubt even if Network vendors would provide an updated firmware version those routers would never receive it. Besides that what other big concerns are in your view ?
> 
> With regards the points some people frequently raise about that any extension to IPv4 space is a killer to IPv6 Deployments to come, I personally refuse to believe in that, at least not in a binary way was sometimes is preached. I see that regardless the improvements in IPv6 deployment (which I obviously support and actively practice on my day by day) I always had the impression that we will live with the IPv4 internet for at least, in a very optimistic scenario for another 10 years or more. Recently I read a report about this subject that mentioned at least another 20 years.
> 
> And even when it is said that no matter how much IPv4 becomes available it will never be enough and would be exhausted quiet quickly (probably true). Well, I would say that if there is any chance for these 'new' IPv4 to become functional they should never be intended to be used as they have been in the last decades, but instead to certain and specific usages as mainly facilitate IPv6 deployment and translation techniques, Hosting and other scenarios where no-IPv4-at-all is not an option.
> 
> Appreciate any comments and contributions to make it possible to understand this subject better.
> 
> Best regards
> Fernando Frediani
> 
> 
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