On Wed, Jan 10, 2024 at 11:06 AM Tom Beecher <beecher@beecher.cc> wrote:
There's a whole bunch of software out there that makes certain assumptions about allowable ranges. That is, they've been compiled with a header that defines ..
Of course correct. It really depends on the vendor / software / versions in an environment. A lot of vendors removed that years ago, because frankly a lot of large networks have been using 240/4 as pseudo RFC1918 for years. Others have worked with smaller vendors and open source projects to do the same.
It's consistently a topic in the debates about 240/4 reclassification.
There's debates still? I gave up. After making 240/4 and 0/8 work across all of linux and BSD and all the daemons besides bird (which refused the patch , I took so much flack that I decided I would just work on other things. So much of that flack was BS - like if you kill the checks in the OS the world will end - that didn't happen. Linux has had these two address ranges just work for over 5 years now. 240/4 is intensely routable and actually used in routers along hops inside multiple networks today, but less so as a destination. I would really like, one day, to see it move from reserved to unicast status, officially. I would have loved it if 0/8 was used by a space RIR, behind CGNAT, for starters, but with a plan towards making it routable. I am not holding my breath. The principal accomplishment of the whole unicast extensions project was to save a nanosecond across all the servers in the world on every packet by killing the useless 0/8 check. That patch paid for itself the first weekend after that linux kernel deployed. It is the simplest, most elegant, and most controversial patch I have ever written. https://news.ycombinator.com/item?id=20430096
On Wed, Jan 10, 2024 at 10:45 AM Michael Butler <imb@protected-networks.net> wrote:
On 1/10/24 10:12, Tom Beecher wrote:
Karim-
Please be cautious about this advice, and understand the full context.
240/4 is still classified as RESERVED space. While you would certainly be able to use it on internal networks if your equipment supports it, you cannot use it as publicly routable space. There have been many proposals over the years to reclassify 240/4, but that has not happened, and is unlikely to at any point in the foreseeable future.
While you may be able to get packets from point A to B in a private setting, using them might also be .. a challenge.
There's a whole bunch of software out there that makes certain assumptions about allowable ranges. That is, they've been compiled with a header that defines ..
#define IN_BADCLASS(i) (((in_addr_t)(i) & 0xf0000000) == 0xf0000000)
Michael
-- 40 years of net history, a couple songs: https://www.youtube.com/watch?v=D9RGX6QFm5E Dave Täht CSO, LibreQos