Estimate effective WAN throughput gains from compression, caching and deduplication.
WAN optimization appliances increase the effective, perceived throughput of a fixed physical link by reducing how much data actually needs to cross it — deduplication avoids re-sending data blocks the remote end already has cached, and compression shrinks the data that must be sent. These two techniques stack multiplicatively: a link that only physically carries the actual bandwidth can behave, from an application's perspective, as if it carries dedup_ratio × compression_ratio times that bandwidth for suitable (compressible, redundant) traffic patterns.
Effective bandwidth
effective_bw = actual_bw × dedup_ratio × compression_ratio
No — the underlying physical bandwidth is unchanged. WAN optimization reduces the volume of data that must actually cross the link for a given amount of useful data delivered, which produces the same practical effect as a faster link for compatible traffic, but doesn't help traffic types that don't compress or deduplicate well (e.g. already-compressed video, encrypted traffic).
Deduplication benefits most from repetitive data patterns — file shares, backups, and VDI traffic often see high dedup ratios because similar blocks recur across transfers. Compression benefits most from data with statistical redundancy — text, logs, and uncompressed formats compress well, while already-compressed or encrypted data barely compresses further, sometimes even growing slightly.
Encrypted traffic (VPN tunnels, TLS/HTTPS, already-encrypted backups) looks like random noise to both deduplication and compression algorithms, so it typically sees minimal benefit unless the WAN optimizer can inspect it before encryption or the endpoints support optimization-aware encryption.