Private Network Using 240.0.0.0/4 Netblock

Installing and Using OpenWrt Network and Wireless Configuration
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Dear Colleagues:

  1. I have an idea of making use of the reserved 240.0.0.0/4 netblock to create a large private network for various applications.

  2. I bought a TP-Link Archer C20 AC750 V4.1. After initial tests on the unit out of the box, I loaded OpenWrt Ver. 18.06.1 into it and repeated the same procedure. Below is the result of the OpenWrt version which is essentially the same as that from the factory condition. It shows that the IP address of the router may be set to various values and operate normally. Although, cases F & G do seem to show some limitations.

https://www.dropbox.com/s/3d1gdwlkbjba8x3/RAN-TP-LinkArcherC20AC750_OpenWrt18.06.1.pdf?dl=0

  1. When I attempted to set the IP address to 240.1.0.1, AC750 factory software would not accept it. So, the unit remained operational with the last setting. When I tried with OpenWrt, it appeared to accept the change. Upon completing the update and reboot, however, the unit became non-operational (IP addresses in the 169.254.0.0/16 range). I had to reload the Ver. 18.06.1 to restore the operation.

  2. Does any colleague know what netblocks will behave this way? And, is there anyway to make them operational?

Thanks a lot in advance.

2

persistence is everything ^^

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Dear "colleague"

In your multiple, previous threads, you have been linked the IANA registry and multiple RFCs that govern the behavior of netblocks.

You have been told that support of OEM firmware is off topic for this board.

Despite you having claimed to have an MIT degree, even here you have failed to describe a meaningful question.

No this is not an invitation for you to spout more about your commercial endeavor and your brilliant colleagues and co-authors, and state how well your colleagues that help you out will be rewarded.

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Hi @OugCPC - I don't understand your intended application, but I want to be sure you are aware that the use of the 240.0.0.0/4 netblock is not guaranteed to work. A portion of whois 240.0.0.0 response shows the following:

Comment:        Addresses starting with 240 or a higher number 
Comment:        have not been allocated and should not be used, 
Comment:        apart from 255.255.255.255, which is used for 
Comment:        "limited broadcast" on a local network.
Comment:
Comment:        This block was reserved by the IETF, the organization that 
Comment:        develops Internet protocols, in the Standard document 
Comment:        and in RFC 1112.  The documents can be found at:
Comment:        http://datatracker.ietf.org/doc/rfc1112
Ref:            https://rdap.arin.net/registry/ip/240.0.0.0

This means that most ISPs would be likely (and entitled) to drop any traffic with a destination in that netblock. (That may also be the reason that some factory firmware will not accept that address.)

So it seems to me unreasonable to base a design on this netblock if you ever want the traffic to leave your house/business. And if you are only attempting to communicate inside the building, private address ranges and VLANs are well-documented, and work out of the box.

Best regards
Rich

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