pts: 1 ND reachable time is 30000 milliseconds Default router is FE80::212:43FF:FEB9:2C70 on FastEtherneto/o Pretty cool, huh? Maybe, and maybe not. In my experience, letting routers build their own networks is a dangerous proposition. When every network can talk to every other network, developers start using paths that shouldn't exist. Then when you later lock them down, applications break and you're the bad guy. Even worse, tests like the CCIE lab exam will take advantage of this autoconfiguration and if you're not sure what's happening, you'll fail the lab. So the natural question for me is, how do we disable this behavior? You can suppress the router advertisements on an interface basis with the ipv6 nd- suppress-ra interface command: R1 (config-if)#int fo/o (config-if)#ipv6 nd suppress-ra 1(config-if)#int fo/1 1(config-if)#ipv6 nd suppress-ra Once I do this, the other routers will not receive these advertisements or learn the default router, and the dynamic network will break. Now for a final step, let's add traditional routes and a default gateway on R6 and R4: First, I'll add a static route on R6 to allow access to the : 101: subnet: R6(config)#ipv6 route aaaa:aaaa:aaaa:101::/64 aaaa: aaaa:aaaa:1::1 On R4, I'll add a default gateway instead. With IPv6, default routes are a little different than they are in IPv4, mostly due to the way addresses are written. While you might be Chapter 37: IPv6 tempted to write 0:0:0:0::0/0 to match any route, that will make you look like an IPv6 newbie (though it works): R4 (config)#ipv6 route 0:0:0:0::/0 aaaa:aaaa:aaaa:101::1 The supercool-IPv6-guy way to reference the 0/0 route in IPv6 is with ::/0: R4(config)#ipv6 route ::/0 aaaa:aaaa:aaaa: 101: We can look at our routes with the show ipv6 route command. Here are the outputs from all three routers: R6#sho ipv6 route IPv6 Routing Table - 6 entries Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP U - Per-user Static route I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary 0 - OSPF intra, OI - OS