[Bloat] mDNS

[Mark Andrews]

> On 28 Feb 2024, at 05:52, Rich Brown via Bloat <bloat at lists.bufferbloat.net> wrote:
> 
> 
> 
>> On Feb 27, 2024, at 12:00 PM, bloat-request at lists.bufferbloat.net wrote:
>> 
>> On 2/26/2024 6:28 AM, Rich Brown via Bloat wrote:
>>> - Avoid the WAN port's DHCP assigned subnet (what if the ISP uses 
>>> 192.168.1.0/24?)
>> 
>> I recently got ATT fiber and its modem won't let me assign from 
>> 10.0.0.0/8! So I put a Raspberry Pi 4 in front of it.
> 
> Exactly! There are no rules about what subnet range an ISP's gear will assign to DHCP devices.

Actually there are rules.  Go read RFC 1918 and you will see it specifically excludes this use.  RFC 1918 addresses are for intra enterprise devices.  CPE devices, by function, are not intra enterprise.  CPE devices are shared devices used by both the ISP and the customer regardless of who owns the hardware.

100.64/10 is an example of a shared space for numbering CPE devices.  It was allocated specifically because RFC 1918 addresses are inappropriate for numbering CPE devices by ISPs.

Mark

> So (I believe) it becomes incumbent on OpenWrt to be smarter than the ISP's router (shouldn't be hard) and pick a separate subnet for its LAN & wireless interface. (Clearly, OpenWrt could default to 192.168.1.0/24, but if that's that range the ISP is using, it could switch to 192.168.2.0/24. I think that's all the flexibility that's required...)
> 
> And then advertise a mDNS name to make it easy for humans to connect. Who would notice?
> 
> - Newcomers wouldn't - they'd just connect and configure as described in the Wiki
> - Grizzled OpenWrt old-timers wouldn't notice either, because they will have set their ISP device to use some other address range.
> 
> Any reason not to build this into OpenWrt? Thanks.
> 
> Rich
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka at isc.org