Restrictions For Radius Server Load Balancing - Cisco Catalyst 2960 series Configuration Manual

Restrictions for RADIUS Server Load Balancing

• RADIUS must be configured for functions such as authentication, accounting, or static route download.
Restrictions for RADIUS Server Load Balancing
• Incoming RADIUS requests, such as Packet of Disconnect (POD) requests, are not supported.
• Load balancing is not supported on proxy RADIUS servers and for private server groups.
Information About RADIUS Server Load Balancing
RADIUS Server Load Balancing Overview
Load balancing distributes batches of transactions to RADIUS servers within a server group. Load balancing
assigns each batch of transactions to the server with the lowest number of outstanding transactions in its queue.
The process of assigning a batch of transactions is as follows:
1 The first transaction is received for a new batch.
2 All server transaction queues are checked.
3 The server with the lowest number of outstanding transactions is identified.
4 The identified server is assigned the next batch of transactions.
The batch size is a user-configured parameter. Changes in the batch size may impact CPU load and network
throughput. As batch size increases, CPU load decreases and network throughput increases. However, if a
large batch size is used, all available server resources may not be fully utilized. As batch size decreases, CPU
load increases and network throughput decreases.
There is no set number for large or small batch sizes. A batch with more than 50 transactions is considered
Note
large and a batch with fewer than 25 transactions is considered small.
If a server group contains ten or more servers, we recommend that you set a high batch size to reduce
Note
CPU load.
Transaction Load Balancing Across RADIUS Server Groups
You can configure load balancing either per-named RADIUS server group or for the global RADIUS server
group. The load balancing server group must be referred to as "radius" in the authentication, authorization,
and accounting (AAA) method lists. All public servers that are part of the RADIUS server group are then
load balanced.
You can configure authentication and accounting to use the same RADIUS server or different servers. In
some cases, the same server can be used for preauthentication, authentication, or accounting transactions for
a session. The preferred server, which is an internal setting and is set as the default, informs AAA to use the
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
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