Mobile IP Registration Revocation
▀ Overview
▄ Cisco ASR 5x00 Packet Data Network Gateway Administration Guide
410
Overview
Registration Revocation is a general mechanism whereby either the HA or the FA providing Mobile IP functionality to
the same mobile node can notify the other mobility agent of the termination of a binding. This functionality provides the
following benefits:
Timely release of Mobile IP resources at the FA and/or HA
Accurate accounting
Timely notification to mobile node of change in service
Mobile IP Registration Revocation can be triggered at the FA by any of the following:
Session terminated with mobile node for whatever reason
Session renegotiation
Administrative clearing of calls
Session Manager software task outage resulting in the loss of FA sessions (sessions that could not be recovered)
Important:
Registration Revocation functionality is also supported for Proxy Mobile IP. However, only the HA
can initiate the revocation for Proxy-MIP calls.
Mobile IP Registration Revocation can be triggered at the HA by any of the following:
Administrative clearing of calls
Inter-Access Gateway handoff. This releases the binding at the previous access gateway/FA
Session Manager software task outage resulting in the loss of FA sessions (for sessions that could not be
recovered)
Session Idle timer expiry (when configured to send Revocation)
Any other condition under which a binding is terminated due to local policy (duplicate IMSI detected, duplicate
home address requested, etc.)
The FA and the HA negotiate Registration Revocation support when establishing a Mobile IP call. Revocation support
is indicated to the Mobile Node (MN) from the FA by setting the 'X' bit in the Agent Advertisement to MN. However
the MN is not involved in negotiating the Revocation for a call or in the Revocation process. It only gets notified about
it. The X bit in the Agent Advertisements is just a hint to the MN that revocation is supported at the FA but is not a
guarantee that it can be negotiated with the HA
At the FA, if revocation is enabled and a FA-HA SPI is configured, the Revocation Support extension is appended to the
RRQ received from the MN and protected by the FA-HA Authentication Extension. At the HA, if the RRQ is accepted,
and the HA supports revocation, the HA responds with an RRP that includes the Revocation Support extension.
Revocation support is considered to be negotiated for a binding when both sides have included a Revocation Support
Extension during a successful registration exchange.
Important:
The Revocation Support Extension in the RRQ or RRP must be protected by the FA-HA
Authentication Extension. Therefore, an FA-HA SPI must be configured at the FA and the HA for this to succeed.
If revocation is enabled at the FA, but an FA-HA SPI is not configured at the FA for a certain HA, then FA does not
send Revocation Support Extension for a call to that HA. Therefore, the call may come up without Revocation support
negotiated.
