Let's say I have a /27 allocation from my ISP, and let's call it: 90.10.200.32/27
The ISP have their router set up as my gateway on address 90.10.200.33. The range 90.10.200.34-62 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 90.10.200.34/28, and set it's gateway to 90.10.200.33
- I configure another interface of the route for the address 90.10.200.49/28, and connect devices to this interface, assigning them addresses in the 90.10.200.50-62 range.
I do not have control over routing tables on the ISP router (90.10.200.33). 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 90.10.200.34 for the 90.10.200.48/28 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.