Anycast applicable to Radius Server Farm ?

Edward B. DREGER eddy+public+spam at
Mon May 8 05:08:21 UTC 2006

JS> Date: Mon, 8 May 2006 12:07:13 +0800 (CST)
JS> From: Joe Shen

JS> Could it be possible to implement IPv4 Anycast architecture for
JS> radius server farm?


JS> Could it be any problem with AAA procedure?

UDP is anycast-friendly.  Your biggest problems are likely to be
authentication database replication/synchronization and merging
accounting records... i.e., nothing really different from standard
RADIUS deployments.

Try ECMP if you want load balancing without the L4-ish gear.  This
implies routers between the NASes and RADIUS boxen, but you _did_
specify anycast. ;-)

Load balancing is trickier when RADIUS servers and NASes live on the
same network segment.  You'll need something a la Windows Advanced
Server or distributed 802.3ad.  I know of no turn-key implementation of
the latter; I played around with it a few years back, but the project
was shelved before completion.  Several modern *ix flavors include
rudimentary 802.3ad support, so implementation should be easier these

(Note that MAC-based technology strays away from "anycast" in the sense
that it operates at L2 instead of L3.)

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