D-Link DWS-3227P - xStack Switch - Stackable Manual de usuario descargar pdf (Pagina 16)

Semaphore Technologies Pvt. Ltd. – (technolo[email protected]om)

using a specific port. Load balancing often involves NAT so that the client of the load-

balanced service is not fully aware of precisely which server is handling its requests.

Some of the layer 4-7 switches can NAT at wire speed. Content switches can often

also be used to perform standard operations such as SSL encryption/decryption to

reduce the load on the servers receiving the traffic, and to centralise the

management of digital certificates.

Some types of application require that repeated requests from a client are directed

at the same application server. Since the client isn't generally aware of which server

it spoke to earlier, content switches define a notion of stickiness. For example,

requests from the same source IP address are directed to the same application

server each time. Stickiness can also be based on SSL Ids, and some content

switches can even use cookies to provide this functionality.

The ServerIron® family of Layer 4-7 switches & Load Balancer

Layer 4 Load Balancer

A typical network router simply sends incoming packets onto the appropriate IP

address on its network. A layer 4 router, more correctly a NAT with port and

transaction awareness, uses a little trickery and sends incoming packets to one or

more machines which are hidden behind a single IP address.

The Layer 4 refers to the 7 layer OSI model. The router is on the Transport Layer

and makes decisions on where to send the packets. Modern load balancing routers

can use different rules to make decisions on where to route traffic. This can be based

on least load, or fastest response times, or simply balancing requests out. This is

also a redundancy method, so if one machine is not up, the router will not send

traffic to it.

Load Balancing Router

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D-Link DWS-3227P - xStack Switch - Stackable Manual de usuario Pagina 16