Here’s one example: In the IPv4 Internet, there are about 830,000 prefixes (network addresses) announced, and the number is growing [1]. Routers at ISPs and so

Here’s one example: In the IPv4 Internet, there are about 830,000 prefixes (network addresses) announced, and the number is growing [1]. Routers at ISPs and sophisticated customers maintain full (“default-free”) routing tables with at least one entry for each prefix. These tables are used for packet forwarding decisions, so lookups have to be fast. Traditionally, a radix tree is used, but some routers use other data structures or specialized hardware. [1] https://www.cidr-report.org/as2.0/ https://www.cidr-report.org/as2.0/