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Re: Anycast applicable to Radius Server Farm ?

  • From: Hugh Irvine
  • Date: Mon May 08 03:14:48 2006

Hello Joe -

Can you indicate in more detail what the problems were with the L4 switch?

If the loadbalancing is done by source/destination IP address pairs, then you can have problems when a target goes down, as all of the source/destination IP address pairs will get switched to another target which then gets into difficulty and you end up with a cascading failure. It is generally preferable to have the loadbalancing done on a weighted per-packet basis, ideally distributed according to round-trip times.

Also note that you can only do per-packet loadbalancing with simple RADIUS, things like EAP that require multiple exchanges of RADIUS requests typically require state to be maintained in the single RADIUS server that is processing the entire EAP sequence.



On 8 May 2006, at 14:07, Joe Shen wrote:


we have a radius server farm. there is a L4 switch
installed behind all servers. Incoming AAA packets are
switched by L4 switch to different servers.

In previous days we met a couple of problems with L4
switch  which degraded our service a lot. Could it be
possible to implement IPv4 Anycast architecture for
radius server farm? Could it be any problem with AAA

Any advice will be highly appreciated


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Have you read the reference manual ("doc/ref.html")?
Have you searched the mailing list archive ( radiator)?
Have you had a quick look on Google (
Have you included a copy of your configuration file (no secrets),
together with a trace 4 debug showing what is happening?

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