As I have received some questions about GLB I will try to answer some of them
here.

What is Global Load Balancing?
Global load balancing is a concept where several data centers answers to a
web site.
In its simplest form you can create a GLB by using DNS to point to the IP
address of your different web sites. This way you can share the load between
your data centers.
But often you want more. Today most modern GLB solution can give you more:
- Direct you to the closest data center (based on IP addresses). (Speed.)
- Make sure the data center is up and running before sending clients
there. (Always up.)
And probably more as well.
Most load balancers, if not all, uses DNS to direct traffic. The GLB is
basically a DNS server that checks the incoming request and makes intelligent
decisions before returning an answer.
This page talks
about why GLB does not work. I do not agree to everything on this page but you
will have to make out your own mind.
What GLB is not
With GLB you only get the solution to distribute traffic between your data
centers. You still have to solve database replication, how to maintain your
files in sync and so forth.
Who are the players?
I have done some research and found these vendors. I have not tried any of
the solutions, only read the product documentation. I am sure there are other
players, but they are sometimes hard to find.
| Player |
Comment |
| F5 Big-IP GTM |
The most expensive solution I have found. I have used F5 products
before and they usually work well. You can only buy this as an
appliance. You can choose to buy it as a GTM only or as a local traffic
management (load
balancer) with GTM on top. |
| Zeus ZXTM GLB |
You can buy this as an appliance or as a VMWare image. Promises good
performance, supports active-active data centers and you can make rules
on how to route traffic. |
| Coyotepoint
Envoy |
Envoy is an add-on to their local load balancer appliance. That is -
you need to buy everything from them. With Envoy you can create policies
for traffic management. |
Labels: F5, network, web