Evaluation of bandwidth enforcement at edge devices

Bandwidth enforcement at edge devices can allocate bandwidth resources according to organizational policy rules. Enterprises often employ such policy-based devices at their organizational edges to manage the narrow but expensive Internet access links. This work designs a novel testbed and uses it to evaluate the functionality and performance of many such devices, including six commercial products and one open source solution. Their policy rules can be categorized into (1) class-based rule; (2) connection rule within a class; (3) bandwidth borrowing rule among classes. The testbed mimics the real-life Internet with heterogeneous Internet delays/delay jitters/packet loss rates, and evaluates the effectiveness of policy enforcement of the above three policy types in terms of accuracy, fairness, stability, robustness, bandwidth borrowing, and voice over IP (VoIP) quality. The test results reveal that (1) sizing the TCP window could cause performance or fairness degradation even under slight packet loss rates; (2) narrowband rate enforcement is more difficult; (3) the voice quality over IP networks significantly depends on the packet sizes of all other traffic when using a narrowband (125 kbit/s) access link. All test results are verified by the vendors and are reproducible through our open tools. Nowadays most benchmark reports are financed by vendors and may be biased. without practical testbeds. Guided by this neutral test, readers can obtain in-depth insights when examining such devices.