What is NetScaler HTTP Compression feature?

NetScaler can perform compression to reduce size of data in transit without any loss. Benefits of compression include - reduced bandwidth consumption, less download time and reduction in other network related performance issues.

This feature is available in NetScaler Platinum and Enterprise Edition license. It is optional in the Standard license.
HTTP Compression on NetScaler is based upon the GZIP and DEFLATE algorithms. Compression feature will compress data within HTML, XML, CSS, text, and Microsoft Office documents. It does not compress any picture format files, JavaScript files, or other web files that are not text related.

What are the capabilities of the HTTP compression feature?

Higher Compression Ratio: NetScaler compression feature can achieve higher compression ratio and it is more significant for Deflate types compression algorithm. For example, if backend server is sending 5 GB of compress-able data then, NetScaler can compress it and send 1 GB of data to client (ratio: 1:5).

Browser Awareness: NetScaler serves compressed data to compression aware browsers only.

Compression Caching: With the integrated caching feature enabled, subsequent requests for the same content are served from the local cache.

Compression throughput metrics

Enabling HTTP compression might have an immediate impact to CPU performance where virtual servers exist and compression is enabled on the virtual server.

The HTTP compression performance numbers is termed as Compression throughput in NetScaler data sheets. Compression Throughput indicates the maximum rate at which a NetScaler appliance can compress and transmit application data.

Note: Compression throughput on NetScaler is measured before compressing the data send to the client.

For example, for MPX 14020 appliance, where L7 throughput is 20 Gbps (Tx + Rx together), compression throughput is 4.4 Gbps (number signifies pre-compression throughput).

The preceding screen shot is from the NetScaler data sheet which contains compression throughput before the data has compressed which may vary based on the NetScaler appliance type, CPU and memory allocated to various NetScaler models.

NetScaler Data Sheet