Network Bandwidth Management
From Linux-VServer
Network Bandwidth Management for Guests is most easily achieved via iptables and tc -- see the Linux Advanced Routing & Traffic Control HOWTO for details ...
Future network implementations (ngnet) will aid with the context tagging of network packets but will not duplicate features already present in the mainline kernels (like traffic shaping and such)
Accounting
The amount of sent/received data at the socket level is already accounted, the actual network traffic has to be accounted by utilizing iptable accounting rules (this will change with ngnet)