Devon IT HC12 Manual de usuario descargar pdf (Pagina 54)

ThinManage 3.1 Administration Manual

The Load Balancer

The load balancer can be implemented either as a hardware or software based solution. The next two sections describe

the nature of each solution.

Software Solution for Load Balancing

One method for accomplishing load balancing would be to use a Round Robin DNS technique. Round robin works by

responding to DNS requests not with a single IP address, but a list of IP addresses. The order in which IP addresses from

the list are returned is the basis of the round robin name. The IP address at the top of the list is returned a set number of

times before it is moved to the bottom, thus promoting the second IP address to the top of the list. This cycle is continual

and allows the DNS server to assist in balancing requests between servers.

Hardware Solution for Load Balancing

The second option for load balancing would be to utilize a hardware component, such as the Cisco LocalDirector

appliance.

Cisco System's LocalDirector is a high-availability, Internet scalability solution that intelligently load balances TCP/IP traffic

across multiple servers. Servers can be automatically and transparently placed in or out of service, and LocalDirector

itself is equipped with a hot standby failover mechanism, eliminating all points of failure for the server farm.

Deciding on which Load Balancing Solution to Use

The only feature a load balancer must absolutely have is the ability to redirect requests to multiple ThinManage servers.

Both of the solutions presented above meet that requirement and are supported by ThinManage. Therefore, you have the

choice to select which method works best for your particular environment -- and budget.

The Stateless Servers

The second tier of the Enterprise Architecture is comprised of multiple, stateless ThinManage servers. Having several

concurrent servers available eliminates a single point of failure that could occur in a basic architecture that simply relies

on one server for all requests. If one server goes offline - whether planned or unplanned - the load balancer can re-route

requests to one of the other servers that are online.

Wikipedia, “Round robin DNS,” last modified 03:40, 18 Oct 2007 < http://en.wikipedia.org/wiki/Round_robin_DNS>

Cisco Systems, “Cisco LocalDirector 400 Series,” 2006 < http://www.cisco.com/warp/public/cc/pd/cxsr/400/index.shtml>.

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Devon IT HC12 Manual de usuario Pagina 54