1. A method of controlling communication networks including a plurality of network elements, comprising: encoding control plane protocol messages using XML markup language; and transferring said encoded messages between said network elements, wherein said messages include a plurality of nested elements, and said nested elements include XML tags, attributes reflecting message type and version number, or a combination of XML tags and attributes reflecting message type and version number, and wherein said content router employs an XML link state protocol to manage links within the network and an XML subscription management protocol that routes customer data based on XML content, and said content router is configured to employ said control plane protocol messages as part of said link state protocol and said subscription management protocol.