WAN optimization

WAN optimization is a collection of techniques for improving

WAN optimization has been the subject of extensive academic research almost since the advent of the WAN.[5] In the early 2000s, research in both the private and public sectors turned to improving the end-to-end throughput of TCP,^[6] and the target of the first proprietary WAN optimization solutions was the Branch WAN. In recent years, however, the rapid growth of digital data, and the concomitant needs to store and protect it, has presented a need for DC2DC WAN optimization. For example, such optimizations can be performed to increase overall network capacity utilization,^[7][8] meet inter-datacenter transfer deadlines,^[9][10][11] or minimize average completion times of data transfers.^[11][12] As another example, private inter-datacenter WANs can benefit optimizations for fast and efficient geo-replication of data and content, such as newly computed machine learning models or multimedia content.^[13][14]

Component techniques of Branch WAN Optimization include deduplication,

Deduplication

Eliminates the transfer of redundant data across the WAN by sending references instead of the actual data. By working at the byte level, benefits are achieved across IP applications.

Data compression

Relies on data patterns that can be represented more efficiently. Essentially compression techniques similar to ZIP, RAR, ARJ etc. are applied on-the-fly to data passing through hardware (or virtual machine) based WAN acceleration appliances.

Latency optimization

Can include TCP refinements such as window-size scaling, selective acknowledgements, Layer 3 congestion control algorithms, and even co-location strategies in which the application is placed in near proximity to the endpoint to reduce latency.^[15] In some implementations, the local WAN optimizer will answer the requests of the client locally instead of forwarding the request to the remote server in order to leverage write-behind and read-ahead mechanisms to reduce WAN latency.

Caching/proxy

Staging data in local caches; Relies on human behavior, accessing the same data over and over.

Forward error correction

Mitigates packet loss by adding another loss-recovery packet for every N packets that are sent, and this would reduce the need for retransmissions in error-prone and congested WAN links.

Protocol spoofing

Bundles multiple requests from chatty applications into one. May also include stream-lining protocols such as

CIFS

.

Traffic shaping

Controls data flow for specific applications. Giving flexibility to network operators/network admins to decide which applications take precedence over the WAN. A common use case of traffic shaping would be to prevent one protocol or application from hogging or flooding a link over other protocols deemed more important by the business/administrator. Some WAN acceleration devices are able to traffic shape with granularity far beyond traditional network devices. Such as shaping traffic on a per-user and per-application basis simultaneously.

Equalizing

Makes assumptions on what needs immediate priority based on the data usage. Usage examples for equalizing may include wide open unregulated Internet connections and clogged VPN tunnels.

Connection limits

Prevents access gridlock in and to denial of service or to peer. Best suited for wide open Internet access links, can also be used links.

Simple rate limits

Prevents one user from getting more than a fixed amount of bandwidth. Best suited as a stop gap first effort for remediating a congested Internet connection or WAN link.

References