Cisco Cisco IOS Software Release 12.2(18)SXF

The Home Agent Director load balances Mobile IP Registration Requests (RRQs) among a set of home 
agents (configured as real servers in a server farm). Home agents are the anchoring points for mobile 
nodes. Home agents route flows for a mobile node to its current foreign agent (point of attachment).

The Home Agent Director has the following characteristics:

Can operate in dispatched mode or in directed server NAT mode, but not in directed client NAT 
mode. In dispatched mode, the home agents must be Layer 2-adjacent to the IOS SLB device.

Can operate in both fast and CEF switching modes.

Does not support stateful backup. See the 

 for more 

information.

Delivers RRQs destined to the virtual Home Agent Director IP address to one of the real home 
agents, using the weighted round robin load-balancing algorithm. See the 

 for more information about this algorithm.

Requires DFP in order to allocate RRQs based on capacity.

For more information about Mobile IP, home agents, and related topics, refer to the Cisco IOS IP 
Configuration Guide, Release 12.2.

IOS SLB provides RADIUS load-balancing capabilities for RADIUS servers. In addition, IOS SLB can 
load-balance devices that proxy the RADIUS Authorization and Accounting flows in both traditional 
and mobile wireless networks, if desired. IOS SLB does this by correlating data flows to the same proxy 
that processed the RADIUS for that subscriber flow.

IOS SLB provides RADIUS load balancing in mobile wireless networks that use service gateways, such 
as the Cisco Service Selection Gateway (SSG) or the Cisco Content Services Gateway (CSG). The 
following mobile wireless networks are supported:

GPRS networks. In a GPRS mobile wireless network, the RADIUS client is typically a GGSN.

Simple IP CDMA2000 networks. CDMA2000 is a third-generation (3-G) version of Code Division 
Multiple Access (CDMA). In a simple IP CDMA2000 mobile wireless network, the RADIUS client 
is a Packet Data Service Node (PDSN).

Mobile IP CDMA2000 networks. In a Mobile IP CDMA2000 mobile wireless network, both the 
Home Agent (HA) and the PDSN/Foreign Agent (PDSN/FA) are RADIUS clients.

IOS SLB provides the following RADIUS load-balancing functions:

Balances RADIUS requests among available RADIUS servers and proxy servers.

Routes RADIUS request retransmissions (such as retransmissions of unanswered requests) to the 
same RADIUS server or proxy server as the original request.

Routes all of a subscriber’s RADIUS flows, as well as all non-RADIUS data flows for the same 
subscriber, to the same service gateway.

Supports multiple service gateway server farms (for example, one farm of SSGs and another of 
CSGs). IOS SLB examines the input interface in a packet to route it to the correct service gateway 
server farm.

Can route data packets to a real server in the CSG farm, then to a real server in the SSG farm.

Routes RADIUS Accounting-Request messages from a RADIUS client to the service gateway that 
processed the RADIUS Access-Request message for the subscriber. The service gateway can then 
clean up the host entry it has created for the subscriber.