Cost-effective Cloud Edge Traffic Engineering with Cascara


Rachee Singh, Sharad Agarwal, Matt Calder, and Paramvir Bahl, Microsoft


Inter-domain bandwidth costs comprise a significant amount of the operating expenditure of cloud providers. Traffic engineering systems at the cloud edge must strike a fine balance between minimizing costs and maintaining the latency expected by clients. The nature of this tradeoff is complex due to non-linear pricing schemes prevalent in the market for inter-domain bandwidth. We quantify this tradeoff and uncover several key insights from the link-utilization between a large cloud provider and Internet service providers. Based on these insights, we propose Cascara, a cloud edge traffic engineering framework to optimize inter-domain bandwidth allocations with non-linear pricing schemes. Cascara leverages the abundance of latency-equivalent peer links on the cloud edge to minimize costs without impacting latency significantly. Extensive evaluation on production traffic demands of a commercial cloud provider shows that Cascara saves 11–50% in bandwidth costs per cloud PoP, while bounding the increase in client latency by 3 milliseconds.

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@inproceedings {264991,
author = {Rachee Singh and Sharad Agarwal and Matt Calder and Paramvir Bahl},
title = {Cost-effective Cloud Edge Traffic Engineering with Cascara},
booktitle = {18th {USENIX} Symposium on Networked Systems Design and Implementation ({NSDI} 21)},
year = {2021},
isbn = {978-1-939133-21-2},
url = {},
publisher = {{USENIX} Association},
month = apr,