nanog mailing list archives
Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast
From: John Gilmore <gnu () toad com>
Date: Thu, 18 Nov 2021 17:54:55 -0800
Randy Bush <randy () psg com> wrote:
as a measurement kinda person, i wonder if anyone has looked at how much progress has been made on getting hard coded dependencies on D, E, 127, ... out of the firmware in all networked devices.
The drafts each have an Implementation Status section that describes what we know. The authors would be happy to receive updates for any of that information. 240/4 is widespread everywhere except in Microsoft products. It works so reliably that both Google and Amazon appear to be bootlegging it on their internal networks. Google even advises customers to use it: https://cloud.google.com/vpc/docs/vpc#valid-ranges 0/8, and the lowest address per subnet, have interoperable implementations that don't cause problems with legacy equipment, but they are not widely deployed. 0/8 has a few years in Linux & Android kernels and distros. Lowest address is in the most recent Linux and FreeBSD kernels, but not yet in any OS distros. In particular, OpenWRT doesn't implement it yet, which could easily be a fast path to a free extra IP address for anyone who has a compatible home router and a globally routed small network like a /29. We used RIPE Atlas to test the reachability of many addresses that end in .0 and .0.0, and they were reachable from all but one probe that we tried. Amazon offers https://ec2-reachability.amazonaws.com/ for this purpose; try it on your own network! Some embedded TCP stacks treat 127/8 as unicast (simply because they don't special-case much of anything), but otherwise we don't know of any current OS distributions that implement unicast for 127/8. The Linux kernel has long had a non-default "route_localnet" option offering similar but more problematic behavior. I would be happy to fund or run a project that would announce small global routes in each of these ranges, and do some network probing, to actually measure how well they work on the real Internet. We are working with RIPE Atlas already to enable this. I thought it would be prudent to propose the changes in detail to IETF, before "bogus" routes showed up in BGP and the screaming on the NANOG list started. :-/ John
Current thread:
- Re: WKBI #586, Redploying most of 127/8 as unicast public, (continued)
- Re: WKBI #586, Redploying most of 127/8 as unicast public John R. Levine (Nov 18)
- Re: WKBI #586, Redploying most of 127/8 as unicast public Joe Maimon (Nov 18)
- Re: WKBI #586, Redploying most of 127/8 as unicast public Justin Streiner (Nov 18)
- Re: WKBI #586, Redploying most of 127/8 as unicast public David Conrad (Nov 18)
- Re: WKBI #586, Redploying most of 127/8 as unicast public Jim (Nov 18)
- Re: WKBI #586, Redploying most of 127/8 as unicast public Nick Hilliard (Nov 18)
- Re: WKBI #586, Redploying most of 127/8 as unicast public Steven Bakker (Nov 18)
- Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast John Gilmore (Nov 18)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast Nick Hilliard (Nov 18)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast Randy Bush (Nov 18)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast John Gilmore (Nov 18)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast David Conrad (Nov 18)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast Nick Hilliard (Nov 19)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast Joe Maimon (Nov 19)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast Nick Hilliard (Nov 19)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast Joe Maimon (Nov 19)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast Zu (Nov 19)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast William Herrin (Nov 19)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast ML (Nov 20)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast Mark Andrews (Nov 20)
- Re: Redeploying most of 127/8, 0/8, 240/4 and *.0 as unicast Jay Hennigan (Nov 20)