Let's say I have a /27 allocation from my ISP, and let's call it: 220.127.116.11/27
The ISP have their router set up as my gateway on address 18.104.22.168. The range 22.214.171.124-62 are free for me to allocate. I need to add a routed subnet behind this network, that is reachable from the internet. Can I do this by dividing my prefix? Something like this:
- I connect a router to the ISP network and give it the address 126.96.36.199/28, and set it's gateway to 188.8.131.52
- I configure another interface of the route for the address 184.108.40.206/28, and connect devices to this interface, assigning them addresses in the 220.127.116.11-62 range.
I do not have control over routing tables on the ISP router (18.104.22.168). Is it possible to do this, or something like it without BGP? As far as I can tell, outbound routing would work fine, but I am confused as to whether to ISP router, which obviously only knows about the /27 will be able to direct packets to 22.214.171.124 for the 126.96.36.199/28 network.
Is there another way to do this that does not involve BGP or having the ISP alter the configuration of their router?
Edit: Just to make it clear, the question is whether this is possible without the ISP changing the routing table on their equipment. As such, what I really want to know is whether this form of subnetting can be done "transparently", so to speak, without altering the configuration of the next upstream device.