The Cisco 2500 Platform

The Cisco 2500 series router is available in a wide array of fixed configurations, and depending
on the model, it can support Ethernet, Token Ring, serial, and ISDN BRI connections. Some
models include an integrated Ethernet hub.

Note:
Most of the 2500 series routers are end-of-sale and cannot be ordered. The
2600XM series provides the best replacement; however, some users might
wish to review the 3700 series for more advanced branch and small office
installations. Cisco continues to sell the 2509, 2511, AS2509, and AS2511 platforms,
but prudence dictates review of newer platforms before ordering. But if
you are buying routers yourself to practice on, consider buying some cheap
2500 series on eBay!