45• The unit of data flows sent to the RADIUS server must be consistent with the traffic statistics unit of theRADIUS server. Otherwise, accounting cannot be performed correctly.Enabling the RADIUS trap functionWith the RADIUS trap function, a NAS sends a trap message in either of these situations:• The status of a RADIUS server changes. If a NAS sends and retransmits an accounting orauthentication request to a RADIUS server but gets no response before the maximum numberof transmission attempts is reached, it considers the server unavailable and sends a trapmessage. If the NAS receives a response from a RADIUS server in block state, the NASconsiders that the RADIUS server is reachable again and also sends a trap message.• The ratio of the number of failed transmission attempts to the total number of authenticationrequest transmission attempts reaches the threshold. This threshold ranges from 1% to 100%and defaults to 30%. Currently, you can configure this threshold only through MIB. Thisfailure ratio is generally small. Therefore, if you see a trap message triggered due to a higherfailure ratio, check the configurations on the NAS and the RADIUS server and thecommunications between them.Follow these steps to enable the RADIUS trap function:To do… Use the command… Remarks1. Enter system view system-view —2. Enable the RADIUS trapfunctionradius trap { accounting-server-down |authentication-server-down }RequiredDisabled by defaultSpecifying the source IP address for RADIUS packets to besentYou can specify an IP address as the source address for RADIUS packets to be sent on a NAS, sothat when the physical outbound interface fails, response packets from the RADIUS server can stillarrive at the NAS.You can specify the source IP address for RADIUS packets to be sent in RADIUS scheme view for aspecific RADIUS scheme, or in system view for all RADIUS schemes whose servers are in a VPN orthe public network.Before sending a RADIUS packet, a NAS selects a source IP address in this order:1. The source IP address specified for the RADIUS scheme.2. The source IP address specified in system view for the VPN or public network, depending onwhere the RADIUS server resides.3. The IP address of the outbound interface.Follow these steps to specify a source IP address for all RADIUS schemes in a VPN or the publicnetwork:To do… Use the command… Remarks1. Enter system view system-view —
