- 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.
If the HA receives
an RRQ with Revocation Support Extension, but not protected by FA-HA Auth
Extension, it will be rejected with “FA Failed Authentication” error.
If the FA receives
a RRP with Revocation Support Extension, but not protected by FA-HA Auth
Extension, it will be rejected with “HA Failed Authentication” error.
Also note that Revocation
support extension is included in the initial, renewal or handoff RRQ/RRP
messages. The Revocation extension is not included in a Deregistration
RRQ from the FA and the HA will ignore them in any Deregistration
RRQs received.