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(Continuation of Question 7/13 studied during 1997-2000)
Background and justification
Recommendation I.371 describes the present set of ATM layer Transfer
Capabilities and related control functions. This capability set may have to be
refined e.g., to improve the support of IP traffic over ATM and to address the
traffic aspects of an enhanced support of traffic using AAL2 (e.g. generated in
mobile networks).
A comparable traffic and congestion control framework should be developed for
IP networks. This includes the description of IP Transfer Capabilities (used to
characterise the properties of the IP transport). In particular the traffic
aspects of a Service Level Agreement (SLA) should be defined. Since several
types of IP transfer capabilities other than best-effort are currently envisaged
for next generation IP networks, it is necessary to define an IP traffic
contract and possibly different best effort traffic classes with relative
priorities. In addition, traffic engineering methods should be developed for IP
networks.
The traffic engineering frameworks defined for IP networks and for ATM
networks should be sufficiently compatible with each other in order to
facilitate the interworking between them.
Items for study
Items related to IP
1. Define the traffic aspects of SLA for IP based services.
2. Specify the IP Transfer Capabilities and associated traffic contract
derived from SLA statements. This should allow the support of real-time and
non-real-time applications.
3. Policy guidelines for defining traffic aspects in a SLA for IP based
services.
4. Specify a traffic and congestion control framework for IP traffic.
5. Specify resource management and congestion control functions.
6. Specify traffic engineering methods and traffic engineering tools for IP.
Items related to ATM
7. Refinement of, with possible extension to, the current set of ATM layer
Transfer Capabilities and the related traffic control functions. This includes
e.g. identifying the traffic management impact of point-to-multipoint
connections , clarifying the applicability of traffic and congestion control
functions to segment OAM cells and clarifying the relationship between ATCs and
AAL types and user applications.
8. Specification of a traffic and congestion control framework for traffic
based on AAL2 (e.g. traffic generated in mobile networks), provided the need for
such functions is agreed on.
9. Determination and specification of the traffic and congestion control
requirements to support the IP Transfer Capability in relevant types of
underlying networks, including the B-ISDN. In particular, specify Intserv and
DiffServ support (e.g., traffic classes with relative priorities).
Items related to interworking between IP and ATM
10. Specification of a common framework for traffic control and congestion
control functions to be applied to traffic in case of interworking between IP
and ATM transfer capabilities. In particular, specification of the traffic
aspects resulting from interworking between MPLS label switched paths and ATM
connections.
Specific tasks and deadlines
Task 1
Creation of a new Recommendation on IP traffic control and congestion control
that defines the notion of an IP traffic contract, which includes the
specification of IP transfer capabilities, and clarifies the relationship with
IP QoS classes.
(deadline: end 2001).
Task 2
Revision of I.371 Recommendation in order to cover the ATM related items,
including the specification, if necessary, of traffic engineering for AAL2
traffic and including the support of IP traffic through an ATM network.
(deadline: end 2002).
Task 3
Creation of a second release of the new Recommendation on IP traffic and
congestion control that includes traffic engineering methods and traffic
engineering tools for IP. This release will also cover the items on IP/ATM
interworking listed above.
(deadline: end 2003).
Relationships
- ITU-T Study Groups on traffic engineering to coordinate the work on traffic
aspects and traffic engineering related to the B-ISDN
- ITU-T Study Groups on signalling to identify the requirements of traffic and
congestion control functions on the signalling protocols
- ITU-T Study Groups on transmission systems to coordinate the work on ATM
equipment
- ITU-R Study Groups on broadcasting and mobile aspects
- ATM Forum to coordinate the work on traffic aspects related to ATM
- IETF to coordinate the work on traffic aspects for the support of IP and the
support of IP over ATM
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