Moby Dick Consolidated System Integration Plan

D0103v1.doc Version 1 6.7.2003
5.2 Signalling Scenarios
This chapter specifies the scenarios between the Moby Dick key components. This are: the Mobile
Terminal (MT), the Radio Gateway (RG), the Access Router (AR), the AAAC Server, the QoS Broker,
the Paging Agent and the Home Agent.
5.2.1 Registration
This chapter specifies the signalling for Registration i.e., the registration of a Mobile Node, which has no
valid entry in its binding cache. Registration describes the process, which takes place after a mobile node
is e.g. switched on and the user of the mobile terminal wants to connect to the Internet. This means either
the user wants to send data or being reachable for any other user in the world. So a registration takes place
when a Mobile Node wants to connect first to any domain. This means that a registration process takes
place as well during a mobility scenario where two administrative domains are involved. If this happens
during an activity of a Mobile Node (the MN send or receives packets), this process is called inter-domain
handover as is described in one of the following sections. In the case the MN is not active, this is just
identical to the case a MN is switched on. The monitoring of the binding cache is part of the decision
handover type decision algorithm and therefore is part of the MTNM. Additionally there is a reregistration
process defined, since the registration is bound to a certain period of time. This re -registration
is triggered by an internal timer and does not differ principally from the registration process.
If this regis tration did not happen correctly, the mobile node is transferred into a de-registered status,
which means that no Internet connectivity is available for the Mobile Node at all.
The Registration process (AAA and Mobility) is initiated after the Care-of-Address (CoA) is acquired by
the Mobile Node. This is performed via the deployment of stateless auto-configuration, avoiding
Duplicate Address Detection (DAD). According to an internal study, the probability for an duplicate IP
address within a network is that low that no additional effort to resolve this is justified within Moby Dick.
However, the CoA does not entitle the user to consume resources apart from the following registration
messages and emergency calls. Note that in the envisaged QoS architecture, other type of services can be
available to the user, depending on the specific network policy.
The registration scenario has been developed in a two step approach. In the first step, AAA signalling and
MIP signalling is completely separated. The advantage of this is that there is no interface required
between AAA and MIP. The disadvantage is that the registration takes longer. Furthermore in the first
step an existing security association is needed between MN and HA. In the second step this association is
build dynamically. Furthermore in the second step the AAA architecture even could be used for dynamic
HA discovery.
In the first step (Figure 96) the MN sends an AA request via the user registration protocol to the AR. The
AR sends an AA request via AAA protocol to his AAAC.f, which forwards the request to the AAAC.h
according to the NAI. The AAAC.h authenticates and authorizes the user and sends a AAA protocol reply
back to the AAAC.f. In this message the network permissions of the user are already indicated. The
AAAC.f may then perform local global authorization decisions. The AAAC.f sends back a reply to the
AR, which forwards all relevant data to the MN via the user registration protocol. At the same time, the
AAAC.f dumps on the local QoS.f the relevant network parameters for the services authorized for that
user. Standard Mobile IP implementation send out an Binding Update (BU) immediately after the CoA
acquisition. At the point of time the QoS.f is informed about the users successful registration, this BU is
not any more blocked by the QoS attendant located at the access router, but forwarded to the home agent.
Afterwards the MN sends a BU to the HA and the HA replies with a BACK. This message goes through
the AR without any requirement for authorization, as the AR will be configured by default with a minimal
bandwidth for signalling. This also assumes that in the WCDMA case these packets will arrive via a
broadcast channel. Upon receiving the AAA answer from AAAC.f, the AR starts an accounting session.
The metering entity at the AR collects these raw data and send is in a fixed and externally defined interval
to the AAAC.f. The AAAC.f consolidates these data and forwards them to the AAAC.h. The accounting
functionality is configured by the accounting policies contained in the AA response from AAAC.f. The
timer interval T1 describes the interval between two forwarding processes of consolidated accounting
data. Within the current Moby Dick implementation this interval is also valid for message “10”, which is
basically inline with the proposed solutions as currently discussed in the IETF. Theoretical work is
ongoing to decouple this which would lead to a more intelligent behaviour of the AAAC.f consolidating
the data received from the AAA Attendants as well. T2 describes the interval for the re-registration
process.
Currently Moby Dick Step1 signalling scenario is implemented and brought to the field trial.
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