Connection Multiplexing in NetScaler

Connection Multiplexing in NetScaler -

When the user opens a Web page, the browser sends several requests to the Web server for the various components of the resulting page in many connections between the browser and the server. Each connection to the web server is usually a short-term connection and puts overhead connection management on web servers. Additionally, technologies like AJAX is based on maintaining multiple connections between the browser and the server. Each connection consumes server resources -. Memory, CPU, bandwidth, etc., thus reducing the server's ability to serve new clients

1.1 HTTP allows a browser sends multiple requests on a persistent connection to a server, eliminating some overhead . But content providers disable this feature because many long
lived many client sessions can consume a lot of resources on the server and can lead to DoS for other clients.

TCP multiplexing is a technique that allows the reuse of existing TCP connections. Each configuration of the TCP connection and removal is a head on both servers and NetScaler. By establishing connections with the server once and use them to serve multiple client requests, NetScaler helps fastest time from servers and improving response capacity.

In NetScaler, TCP multiplexing connection works as follows:

1. NetScaler maintains reuse connection pool - a pool of active connections with servers that can be used to process new customer requests
2. When a client request is received, NetScaler checks for an available connection in the pool reuse
3. If a connection is available in the recycle pool it is used to send the customer's request and get data from the server
4. If a connection is not available in the recycling pool, NetScaler creates a new connection to the selected server
5. in both cases, once the client request is served, the connection is returned to the reuse pool to serve future requests for the same or another customer

It is important note that multiple applications are not sent simultaneously on the server-side connection. In other words server side connections are used to send requests sequentially and after serving each request connections are provided to reuse the pool. Another interesting aspect of the multiplex connection is only to serve multiple requests from the same client, several server-side connections from the reuse pool can be used.

While multiplexing is done at the TCP again it is not applicable to all types of services supported over TCP. NetScaler supports connection multiplexing for

1. HTTP - Multiple requests from several customers are sent on the same connection with the server
2. SSL - avoids CPU intensive key exchange for each new connection
3. DataStream - several client-side applications are made on the same server-side connection

NetScaler provides configuration parameters (such maxconn and maxreq) to control the use of multiplexing limiting the number of requests can be sent on a single server connection to each level of service or to disable the function globally. HTTP profile also provides levers to control how the multiplexing should behave for HTTP services.

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