* Blake Hudson > One thing not mentioned so far in this discussion is using PPPoE or some > other tunnel/VPN technology for efficient IP utilization. The result > could be zero wasted IP addresses without the need to resort to > non-routable IP addresses in a customer's path (as the pdf suggested) > and without some of the quirkyness or vendor lock-in of using ip > unnumbered. > > PPPoE (and other VPNs) have many of the same downsides as mentioned > above though, they require routing cost and increase the complexity of > the network. The question becomes which deployment has more cost: the > simple, yet wasteful, design or the efficient, but complex, design.
<shameless plug alert> Or, simply just use IPv6, and use a stateless translation service located in the core network to provide IPv4 connectivity to the public Internet services. This allows for 100% efficient utilisation of whatever IPv4 addresses you have left - nothing needs to go to waste due to router interfaces, subnet power of 2 overhead, internal servers/services that have no Internet-available services, etc...all without requiring you to do anything special on the server/application stacks to support it (like set up tunnel endpoints), add dual-stack complexity into your network, or introduce any form of stateful translation or VPN service into your network. Here's some more resources: http://fud.no/talks/20130321-V6_World_Congress-The_Case_for_IPv6_Only_Data_Centres.pdf http://tools.ietf.org/html/draft-anderson-siit-dc-00 In case you're interested in more, Ivan Pepelnjak and I will host a (free) webinar about the approach next week. Feel free to join! http://www.ipspace.net/IPv6-Only_Data_Centers BTW: I hear Cisco has implemented support for this approach in their latest AS1K code, although I haven't confirmed this myself yet. Tore