Since my previous Asus WL-500gP was broken due to a power outage, it was time for a new one. Some requirements for a new router where; IPv6, 802.11a/n and gigabit Ethernet switch ports. The Asus only had the IPv6 requirement since I installed OpenWrt on it.

The Cisco EA4500 was one that supports all this. Since I quickly needed a new router I bought this one at a local reseller.

I installed this router at home and found out that this router supports native IPv6, but only via auto-configuration and DHCPv6. Manual IPv6 addresses cannot be configured and static IPv6 routing is also not an option.

Since my previous setup was static routing with IPv6, I needed some changes on the Internet Service Provider side. Luckily I do the configuration and administration for this ISP as a day job. So I introduced DHCPv6 as a configuration option for customers.

This is very easy to setup. The router on the ISP site is an Cisco ASR 1002, with an ATM interface to a DSL provider.

First the configuration for static IPv6 routing was as follow (only IPv6 relevant commands):

interface ATMx/x/x.xx point-to-point
 atm route-bridged ipv6
 ipv6 address 2001:xxxx:xxxx:xxxx::x/64
 ipv6 enable
!
ipv6 route 2001:xxxx:xxxx:xxxx::/64 ATMx/x/x.xx 2001:xxxx:xxxx:xxxx::x

Now the configuration with DHCPv6 is (again only IPv6 relevant commands):

interface ATMx/x/x.xx point-to-point
 atm route-bridged ipv6
 ipv6 address 2001:xxxx:xxxx:xxxx::x/64
 ipv6 enable
 ipv6 nd other-config-flag
 ipv6 dhcp server ipv6-dhcp-pool
!
ipv6 dhcp pool ipv6-dhcp-pool
 prefix-delegation 2001:xxxx:xxxx:xxxx::/64 xxxxxxxxxxxxxxxxxxxxxxxx
 dns-server 2001:xxxx:xxxx:xxxx:x
 dns-server 2001:xxxx:xxxx:xxxx:x

The EA4500 on the client side does a DHCPv6 request. The ASR on the ISP side replies and sends a prefix for the local LAN side and the DNS servers. The EA4500 advertises the /64 prefix and its own IPv6 address for DNS resolving on the local LAN via router advertisements (RA).