OpenERP (now Odoo) bandwidth usage can vary depending on several factors such as the number of users, the amount of data being transferred, and the specific modules being used.

It's difficult to find specific data on the bandwidth usage of OpenERP versions 6.1 and 7.0 as it can vary greatly depending on the specific implementation and usage of the system. However, it's generally considered to have a relatively low bandwidth usage compared to other enterprise software.

Odoo recommends a minimum of 512 kbps for a stable connection.

You can find more information on the technical requirements for running Odoo on their website: https://www.odoo.com/documentation/13.0/setup/deploy.html#technical-requirements

Additionally, you can measure the bandwidth usage by using network monitoring tools to track the amount of data transferred in and out of your Odoo server.

It's also important to note that bandwidth usage can be reduced by optimizing the network connection, compressing data, and using a Content Delivery Network (CDN) for serving static files.