This is my latest network layout. I now have port channels using the Etherchannel protocol between my physical 3560 "core" switch and a Nexus 1000V switch in each of my 2 ESXi hosts. One of my ESX hosts, ESX2, I use for testing purposes and the other ESX host, ESX1, is more or less used for my production network. I have my BES (BlackBerry Enterprise Servers), Active Directory, Exchange, DNS and web servers (ie: this site!) on ESX1. I have other devices not pictured taken from the virtual product portfolio of Cisco's....devices like ASA1000V, VSG, virtual email security appliance (ESAv) and virtual web security appliance (WSAv). My main firewalls are currently Cisco ASAv (virtual ASAs) configured Active/Standby between the two ESXi hosts.
Lots of fun!
I was faced with the problem that when my tenants aren't in our townhouse I have no one to reboot the DSL modem when it loses sync. Why is this a problem? It's because my "data centre" is there. Email servers, this web server, etc., are all hosted there. My DSL provider regularly runs into uptime issues (don't they all?) so I needed a way to automatically reboot the modem every day in the wee hours of the morning. So what to do?
You can run a 6to4 tunnel (like the ones www.he.net offer for free) through an IPv4 router. It simply tunnels IPv6 packets inside an IPv4<-->IPv4 tunnel.
[IPv6 LAN Subnet]<--->[IPv6/IPv4 router]<---IPv4 Internet---->[IPv4/IPv6 tunnel broker peer]<--IPv6 Internet-->