• Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint

Load Balancers

Load balancing and caching are moving out of dedicated boxes and services and into the network itself, especially into routers.

LocalDirector and DistributedDirector

Cisco (http://www.cisco.com/) sells load balancing products named LocalDirector and DistributedDirector. LocalDirector is a dedicated hardware box that cannot be used for anything else once it is obsolete. It is also a single point of failure and may itself become a bottleneck, though it can be configured in a fail-safe configuration — by having two or more of them as a cluster. Go to http://www.cisco.com/, and search for “localdirector” to get more details. LocalDirector rewrites IP headers to redirect a connection to the local server with the most available capacity. It apparently judges capacity by network usage rather than server machine statistics because it runs no processes on the actual web server. Because of this, it is not a true load balancing tool and may not be appropriate for use with servers of differing capacity. The end user, application, and DNS server have no idea that this sort of balancing is happening; it’s transparent to them. This lets many servers share one externally visible IP address, rather like Resonate.


PREVIEW

                                                                          

Not a subscriber?

Start A Free Trial


  
  • Creative Edge
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint