L3A: a protocol for layer three accounting

Accounting protocols are used to quantify traffic to support billing, QoS assurances, and other objectives. Current protocols do not provide complete security for this purpose because of the threat of 'cramming' attacks in which unauthenticated parties can introduce traffic that the accounting system attributes incorrectly. In this paper we explain this vulnerability and introduce a protocol, layer three accounting (LSA), that addresses it through the coordinated establishment of a family of IPsec tunnels. Our goal is to give a practical specification and implementation of the protocol and show its efficiency. We demonstrate that the latency for setting up and tearing down L3A connections is about one third slower than one gets for end-to-end connections alone, but the bulk rate of transfer is improved by 100% over the typical alternative configuration for accounting.