On Thu, Sep 28, 2023 at 2:25 PM VOLKAN SALİH <volkan.salih.06@gmail.com> wrote:
I believe, ISPs should also allow ipv4 prefixes with length between /25-/27 instead of limiting maximum length to /24..
It is because BGP research and experiment networks can not get /24 due to high IPv4 prices, but they have to get an IPv4 prefix to learn BGP in IPv4 world.
Hello, Each BGP route advertised into the global table is expensive. Not for the advertiser... for everyone else. See https://bill.herrin.us/network/bgpcost.html Caveat that the document is based on 2008 data. The numbers (though probably not their shape) have changed.
What do you think about this?
I think you'll convince the IETF to release the Class-E space before you convince the ISPs to broadly honor sub-/24 prefixes.
What could be done here?
In principle, a company could make a business out of announcing a large block from a bunch of peering points and then tunneling (vpn) parts of it back to customers with sub-/24 assignments. With a broad enough selection of peering points, the routing would not be too inefficient. And it would divorce the IP addresses from the last-mile Internet infrastructure, allowing you to take your addresses with you as long as you kept paying the tunnel company. In practice... there's not enough money in it. If you could ante up the cost, you could find a way to qualify for and acquire a full /24.
Is it unacceptable; considering most big networks that do full-table-routing also use multi-core routers with lots of RAM?
You're thinking of DRAM. But that's not the way it works. Some routers use heavily parallel routing engines, each of which need enough dram to hold the full forwarding information base and which can suffer from CPU cache exhaustion even then. Others use an expensive kind of memory called a TCAM that's very fast but both expensive and power hungry, so generally not sized for huge numbers of tiny routes. Regards, Bill Herrin -- William Herrin bill@herrin.us https://bill.herrin.us/