* [[http://www.cisco.com/en/US/products/hw/routers/ps221/products_configuration_example09186a008073e078.shtml|LAN-to-LAN IPsec Tunnel Between Two Routers Configuration Example]]
  * [[http://www.cisco.com/en/US/tech/tk872/technologies_configuration_example09186a00800b49a5.shtml|IPv6 Tunnel through an IPv4 Network]]

  * http://www.cisco.com/en/US/products/hw/routers/ps259/prod_configuration_examples_list.html
  * http://www.cisco.com/en/US/products/hw/routers/ps259/tsd_products_support_eol_series_home.html
 
===== DHCP client + NAT =====

  * https://learningnetwork.cisco.com/message/81597
  * http://forums.speedguide.net/showthread.php?225673-Cisco-2621-on-Comcast-Cable
  * http://forums.whirlpool.net.au/archive/1395877

===== IPv6 (IOS 12.4) =====

  * http://www.cisco.com/en/US/docs/ios/ipv6/configuration/guide/12_4/ipv6_12_4_book.html