Global Server Load Balancing

Routing & Switching
1

Hi, I have seen a video by René about Global Server Load Balancing from 2011, but there seems to be nothing about this topic in NetworkLessons. The technology seems quite interesting. Was it deprecated by Cisco? Which IOS versions do support it? Is it supported in IOSv? Rui

2

Hello Rui

Yes, you can find Rene’s explanation of this feature at the following GNS3 Vault lab link:

Rene is using a feature known as server load balancing (SLB), which creates a server farm, or a server pool, which is simply a collection of servers that contain the same content. This way, you can send traffic to both servers, allowing them to load balance the total traffic among them.

SLB hasn’t been depricated by Cisco, and is available in many Layer 3 switches. For example, I can see it available in Cisco CML on an IOSvL2 15.2 version L3 switch as you can see below:

SW1(config)#ip slb ?
  dfp           configure Dynamic Feedback Protocol manager
  entries       initial and maximum SLB entries
  firewallfarm  configure an SLB firewall farm
  maxbuffers    Maximum number of buffers
  natpool       define client nat pool
  probe         configure an SLB probe
  route         SLB route
  serverfarm    configure an SLB server farm
  static        configure server initiated connection behaviour
  timers        Configure top level SLB timers
  vserver       configure an SLB virtual server

SW1(config)#ip slb

It isn’t however available on routers such as those with the IOSv.

The SLB feature is a great way to deliver redundancy to two or more servers, but it does require you to deploy two or more identical servers, a process that can have a lot of administrative overhead. However, today there are better practices to achieve the same thing. Things like virtualization have allowed us to create hundreds of virtual servers in minutes and distribute them throughout the world. In addition, IPv6 anycast has also allowed us to route traffic to the physically closest device with that IPv6 address, essentially eliminating the need for any configured load balancing mechanisms between multiple servers.

These are just some of the ways in which the same thing can be achieved much more easily and efficiently.

I hope this has been helpful!

Laz

1 Like
3

Thanks for your detailed reply. Are there examples of using IPv6 anycast or virtualization for server load balancing?

4

Hello Rui

There aren’t any lessons on these particular topics as they are not covered by a Cisco certification. However, you can find out more about these at the following links:

https://www.vmware.com/topics/glossary/content/server-virtualization

I hope this has been helpful!

Laz