Cisco Cisco Packet Data Interworking Function (PDIF) Guía De Administador
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Mobile-IP and Proxy-MIP Timer Considerations
▀ Call Flow Summary
▄ Cisco ASR 5x00 Home Agent Administration Guide
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Call Flow Summary
The following steps describe the call flow as regards the timers that affect a call initiated by the Mobile Node (MN).
1. PPP Negotiation: A data call is initiated by beginning PPP. Once PPP is successfully established, the system
will understand if the call is a mobile IP call or simple IP call. At this point, the system is not aware of the
subscriber username and will use settings from the default subscriber template in the source context or the
context defined by the “aaa default-domain subscriber” setting in the global configuration.
subscriber username and will use settings from the default subscriber template in the source context or the
context defined by the “aaa default-domain subscriber” setting in the global configuration.
2. FA Agent Advertisement: Once the system has determined the call is a Mobile IP call, the FA will send a
Router Advertisement message with a Mobility Agent Advertisement extension. The Mobility Agent
Advertisement includes a Registration Lifetime field. The value of this field will come from one of two places.
The FA service has a configurable setting named “advertise reg-lifetime”. The default value for this setting is
600. A setting in the default subscriber template called “timeout idle” is also a candidate. The default value for
this setting is 0 (null). The smaller of these two configurable parameters is used as the Registration Lifetime
value. Leaving the settings at the defaults will result in an advertised lifetime of 600.
Advertisement includes a Registration Lifetime field. The value of this field will come from one of two places.
The FA service has a configurable setting named “advertise reg-lifetime”. The default value for this setting is
600. A setting in the default subscriber template called “timeout idle” is also a candidate. The default value for
this setting is 0 (null). The smaller of these two configurable parameters is used as the Registration Lifetime
value. Leaving the settings at the defaults will result in an advertised lifetime of 600.
Advertise Reg-Lifetime in FA Service
Timeout Idle in Subscriber Template
Resulting Advertised Registration Lifetime
600
0
600
600
900
600
3600
1200
1200
The device will receive the agent advertisement and send a MIP Registration Request. The device uses the
advertised registration lifetime value as the requested MIP lifetime.
advertised registration lifetime value as the requested MIP lifetime.
3. AAA Authentication and MIP Registration Request: The next step in the MIP process will be to authenticate
the user at the FA. It is at this stage where a failure condition can be introduced.
If the Access-Accept message does not return any values related to timers, the subscribers MIP Registration
Request is sent on to the HA.
If the Access-Accept message does not return any values related to timers, the subscribers MIP Registration
Request is sent on to the HA.
If the Access-Accept message does include an attribute relating to Idle or Absolute timer the FA will evaluate
the requested lifetime from the device to the value returned by the AAA. The FA will treat any Idle or Absolute
timer value returned by the AAA as a maximum value and as such:
the requested lifetime from the device to the value returned by the AAA. The FA will treat any Idle or Absolute
timer value returned by the AAA as a maximum value and as such:
If the requested MIP lifetime from the device is less-than than the returned radius attribute, the lifetime
value is considered valid and the MIP Registration Request is forwarded on to the HA.
If the requested MIP lifetime from the device is greater-than the returned radius attribute, the requested
lifetime value is considered to be too long. The FA will send a MIP Registration Reply to the device
with a response code of
with a response code of
Error 69 - Requested Lifetime Too Long
. In the reply message, the
FA will populate the Lifetime value with the maximum acceptable lifetime. The device may send a
new MIP request with this new lifetime value.
new MIP request with this new lifetime value.
MIP Lifetime Requested by Device
Idle-Timer Value in Access-Accept
Resulting MIP Lifetime Request in MIP Request to HA
3600
(Not Returned)
3600
3600
7200
3600
3600
1800
Failure - Error 69
4. HA Process MIP Request: The HA has now received a Mobile IP Registration request forwarded by the FA on
behalf of the device. The MIP request contains the username and the requested lifetime (as well as other