International Telecommunication Union
ITU-T
NGN Signalling requirement
to support QoS
Tina Tsou (tena@huawei.com)
RACF functional architecture defined in Rec. Y.2111
ITU-T
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The relevant functional entities are:
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the Service Control Functions;
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the Network Attachment Control Functions;
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the Policy Decision Functional Entity (PD-FE) within the Resource and Admission Control Functions
(RACF);
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the Transport Resource Control Functional Entity TRC-FE within the RACF;
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the Transport Functions, which contain
-the Policy Enforcement Functional Entity (PE-PE);
-the Transport Resource Enforcement Functional Entity (TRE-FE) (for further study);
-other functions.
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Principles of mapping
ITU-T
o The realization presented in Q.3300 (Introduction to the Q.330x
series of Recommendations) accepts the considerations of
scalability and domain independence that motivated the
development of the functional architecture. As a result, it maps
each functional entity of the functional architecture to a separate
type of physical entity. Furthermore, each reference point is
assumed to map to a separate protocol interface. Because this
latter mapping is one-to-one, each interface is named after the
reference point to which it corresponds (e.g. Rs interface
corresponding to the Rs reference point).
o Depending on the technology involved, it may well be that some of
the physical entities identified in this Recommendation are
combined. In such a case, each combined entity will support the
combined set of interfaces of its component elements, except that
interfaces that would lie between the component elements if they
were separate are absorbed into the interior of the combined
entity.
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Implementations of functional entities
ITU-T
o Mapping from functional to physical entities concerned with
resource admission and control
Functional Entity
Abbrev.
Physical Entity
Abbrev.
Service Control Functions
SCF
Service Control Entity (e.g.
implementation of P-CSCF)
SCE
Network Attachment Control Functions
NACF
Network Attachment Control Entity
NACE
Policy Decision Functional Entity
PD-FE
Policy Decision Physical Entity
PD-PE
Transport Resource Control Functional
Entity
TRC-FE
Transport Resource Control Physical
Entity
TRC-PE
Transport Resource Enforcement
Functional Entity
TRE-FE
Transport Resource Enforcement
Physical Entity
TRE-PE
Transport Functions other than the PE-PE
and TRE-FE
TF
Transport Physical Entity
T-PE
Policy Enforcement Functional Entity
PE-PE
Policy Enforcement Physical Entity
PE-PE
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Example physical realization of the RACF architecture
ITU-T
o An example configuration of the physical entities identified in
the table of previous slide and the interfaces between them.
The figure shows a number of possible interconnection
arrangements. These may vary according to the needs of the
network operators concerned.
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Northbound Interface Singalling Requirements(1)
ITU-T
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1)
Request for resources to support the service
SCE initiates a QoS request to the RAC-PE, with main parameters as follows:
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Connection ID: The unique ID for each request.
It is a requirement to have a "connection ID" to allow the sender and receiver
to match a request with following responses, related modifications and
cancellations. It is left for protocol design to determine which side generates that
connection ID.
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Stream information: information to identify an IP data stream.
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QoS parameters: A description of the service quality requirements of a
stream.
2)
Modification of resources to support service
With respect to some services, it may be necessary to modify the QoS
requirements at anytime during the time the service is running. According to SCE
requirements, RAC-PE modifies the bandwidth that was applied for use the previous
time. Multi-time modification is supported. Main parameters:
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Connection ID: The unique ID for each request.
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Stream information: information to identify an IP data stream.
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QoS parameters: A description of the service quality requirements of a
stream.
3)
Acceptance of resources to support service
Upon completing QoS resource allocation, RAC-PE responds to the SCE by
sending elements of success information. Main parameters are:
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Connection ID.
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Accepted QoS parameters: Among multi-optional QoS capabilities, the
accepted QoS capability is selected.
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Northbound Interface Singalling Requirements(2)
ITU-T
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4)
Rejection of resources to support service
In the case that the RAC-PE cannot meet the QoS request of the SCE, it will
send a rejection for resources to support service to the SCE. Main parameters:
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Connection ID.
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Rejection cause.
5)
Report about resources to support service
In the case of any change in the allocated bandwidth information (the
resource seized by the connection is no longer available, etc.; for example), the
RAC-PE should report it to the SCE. Main parameters:
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Connection ID.
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Current status.
6)
Release of resources to support service
When a service is terminated, the SCE should initiate a request to RAC-PE for
releasing the resource that it has been requested to allocate. According to the SCE
requirement, the RAC-PE takes the bandwidth back. Main parameters:
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Connection ID.
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Release cause.
7)
Response to release of resources
The cancellation of resources should be confirmed to the session. Main
parameters are:
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Connection ID.
–
Execution Results.
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Horizontal Interface Singalling Requirements(1)
ITU-T
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1.
Request for resources to support service
The current RAC-PE initiates a QoS request to the next hop RAC-PE for an interface, with the
following main parameters are:
Connection ID: The unique ID for each request. Each connection may contain multiple streams.
It is a requirement to have a “connection ID” to allow the sender and receiver to match a request
with following responses, related modifications and cancellations. It is left for protocol design to determine
which side generates that connection ID.
Stream information: information to identify an IP data stream
QoS parameters: A description of the service quality requirements of a stream. Many international
standards are available for reference in this respect, hence no further description here.
Path information selected in the local domain and the previous domains (for the MPLS case: By
means of consultation, data stream bearer path LSP sets are distributed between the RAC-PEs, so conditions
of LSP paths selected in the local domain and the previous domains should be provided for each other
among RAC-PEs, so that a peer RAC-PE can correctly select a transit path LSP. For a bidirectional path,
both forward path and backward path are available, such as MPLS label stack. )
Address information of the inter-domain interface: The address of the egress interface in the local
domain (for the non-MPLS case.)
2.
Modification of resources to support service
In respect with some services, it may be necessary to modify the QoS requirements at any time
during the service running. According to the request by the upstream RAC-PE, a RAC-PE modifies the
bandwidth that was applied for use at the previous time. Multi-time modification is supported. Main
parameters are:
Connection ID: The unique ID for each request. Each connection may contain multiple streams.
Stream information: information to identify an IP data stream.
QoS parameters: A description of the service quality requirements of a stream. Many international
standards are available for reference in this respect, hence no further description here.
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4
Horizontal Interface Singalling Requirements(2)
ITU-T
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4.
Rejection of request for resources to support service
When the RAC-PE finds out that the QoS request of the upstream RAC-PE cannot be
satisfied, it will send a rejection response to the upstream RAC-PE. Main parameters are:
Connection ID
Rejection cause
5.
Report about resources to support service
In case of any change with the allocated bandwidth information (the resource seized by
the connection is no longer available, etc.; for example), RAC-PE should report it to the
upstream RAC-PE. Main parameters:
Connection ID
Current status
6.
Release of resources to support service
The upstream RAC-PE requests the downstream RAC-PE for releasing the resource
that has been requested for allocation. Main parameters are:
Connection ID
Release cause.
7.
Response for release for resources
The cancellation of resources should be confirmed to the upstream RAC-PE . Main
parameters are:
Connection ID
Execution results.
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Southbound Interface Singalling Requirements(1)
ITU-T
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1)
QoS configuration information delivery
According to the request of the session/call layer, or an adjacent RAC-PEE,
the RAC-PEE determines a service route and delivers the final strategy to the
corresponding PE-PE. Main parameters are:
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Connection ID.
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Stream information: information to identify an IP data stream.
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QoS parameters.
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Other technology-specific information (e.g., selected information of the
entire path, and delivered-is-complete path information that has been allocated for
the MPLS case).
2)
QoS configuration information modification
With respect to some services, it may be necessary to modify the QoS
requirements at any time during the service running. According to the request by
the session/call layer, or an adjacent RAC-PEE, a RAC-PEE modifies the bandwidth
that was applied for use the previous time. The RAC-PEE determines a service route,
and delivers the modified strategy to the corresponding PE-PE. RAC-PEE and PE-PE
support multi-time modification. Main parameters are:
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Connection ID.
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Stream information: information to identify an IP data stream;
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QoS parameters.
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Other technology-specific information (e.g., selected information of the
entire path, and delivered is complete path information that has been allocated for
the MPLS case).
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5
Southbound Interface Singalling Requirements(1)
ITU-T
o 3)
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QoS configuration response
The PE-PE sets QoS configuration information, and returns a
success/failure indication. Main parameters are:
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Connection ID.
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Execution results.
4) Resource status report
This message is sent in the event of changes in the PE-PE
resource information (e.g., PE-PE fault, LSP is not available, etc.);
the RAC-PEE will maintain the related bandwidth information. Main
parameters are:
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Resource identifier (i.e., the LSP identifier, in the MPLS case).
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Current status.
5) QoS configuration cancellation
When a connection is finished, the configuration information
delivered on the connection should be cancelled. Main parameters
are:
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Connection ID.
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Cause code.
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Interfaces and protocols
ITU-T
Interface
Supporting Entities
Rec. No.
Protocol Base (Note)
Rs
SC-PE, PD-PE
Diameter
Q.3301.1
Rp
Between TRC-PE
RCIP
Q.3302.1
Rw
PD-PE, PE-PE
Introduction
Q.3303.0
COPS-PR
Q.3303.1
H.248
Q.3303.2
Diameter
Q.3303.3
COPS-PR
Q.3304.1
SNMP
Q.3304.2
Rc
TRC-PE, T-PE and PE-PE
Rt
PD-PE, TRC-PE
Diameter
Q.3305.1
Rd
PD-PE to PD-PE (intra-domain)
To be determined
Q.3306.1
Ri
PD-PE to PD-PE (inter-domain)
To be determined
Q.3307.1
Rn
TRC-PE, TRE-PE
For further study
--
NOTES:
Diameter: RFC 3588
COPS-PR: Common Open Policy Service – Policy Provisioning (RFCs 2748, 3084)
SNMP: Simple Network Management Protocol (RFC 3410 and many others)
RCIP: Resource Connection Initiation Protocol, op. cit.
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