Rev PA110.12.20041 Signaled Provisioning of the IP Network Resources Between the Media Gateways in...
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Rev PA1 10.12.2004 1
Signaled Provisioning of the IP Network Resources Between the Media Gateways
in Mobile Networks
Leena Siivola
10.12.2004
Rev PA1 10.12.2004 2
Problem Description
• For circuit switched (CS) traffic the delay and the jitter requirements are strict. That is why the amount of voice calls must be controlled not only from radio networks (RN) side but also from IP multiservice backbone’s point of view.
• The backbone edge nodes, i.e. the Media Gateway, must have ways to control the amount of traffic injected to the network– This must make it possible to give some QoS guarantees for the
voice calls– The network resources will be used more efficiently
Rev PA1 10.12.2004 3
Objectives and Scope
• The objective of this Thesis is to
– describe the current Call Admission Control (CAC) mechanisms in the 3G IP multiservice backbone
– to evaluate the suitability of the NSIS signaling protocol framework for the CAC solution.
Rev PA1 10.12.2004 6
Provisioning Methods in the IP Multiservice Backbone
.
.
MBAC = Measurement Based Admission ControlMPLS = Multiprotocol Label Switching
Rev PA1 10.12.2004 8
Signaled Provisioning
Signaled provisioning is a tempting approach for CAC because it can give ’hard’ QoS guarantees for traffic flows and it can increase the network utilization.
Many QoS signaling protocols exist:• Tenet & ST-II• RSVP with its extensions• YESSIR (Yet another Sender Session Internet Reservations)• Boomerang
RSVP has been the most famous one• Has said to bee too complex and suffering scalability problems-> also other simulation results exist!
The work with the NSIS signaling protocol framework was started, because there was a need for a more lightweight signaling protocol.
Rev PA1 10.12.2004 9
The NSIS Signaling Framework
NSLP = NSIS Signaling Application LevelNTLP = NSIS Transport Level
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The NSIS Signaling for Quality of Service (QoS)
The NSIS QoS signaling framework is based on a two layered architecture:
• NTLP (NSIS Transport Layer Protocol) • NSLP (NSIS Signaling Layer Protocol)
• QoS Model that is being signalled (e.g. Intserv or RMD)
• NSIS without QoS Model is only a framework with many optional features.
Rev PA1 10.12.2004 11
Comparison Between the NSIS QoS Signaling and RSVP
• NSIS can be both sender- and receiver-oriented• NSIS does not support multicast• Mobility support• Bi-directional reservation possible
Rev PA1 10.12.2004 12
NSIS(RMD) ArchitectureIt is not possible to evaluate the NSIS signaling without taking the QoS model into account. The NSIS framework consists of several optional features that can be taken into use.
• Resource Management in Diffserv (RMD) implemented with NSIS
Rev PA1 10.12.2004 13
Successful Reservation
Initiator ReceiverEdge EdgeInterior Interior
Resv(QSpec)
Resv(E2E ignore, QSpec)
Resv(QSpec)
Resv(LQSpec)
Resv(LQSpec) Resv(LQSpec)
ResponseResponse
Response
Rev PA1 10.12.2004 15
Evaluation
+ NSIS framework is flexible and modular
-> it can be used in different ways
+ There are several optional features that can be taken into use
- The resulting QoS protocol is even more complex than RSVP
-> what do we gain with the abstraction level?
Rev PA1 10.12.2004 16
Evaluation: The NSIS(RMD) Implementation as an Example
• Evaluation criteriors:– Per-hop Performance Metrics
• Signaling message processing delay – Per-Reservation Performance Metrics
• Signaling Bandwidth Overhead• Abortive Provisioning• Blocking Probability• Reservation Setup Time
– Applicability of the NSIS(RMD) Signaling to the IP Multiservice Backbone
SCALABILITY AND ROBUSTNESS
Rev PA1 10.12.2004 17
Per-hop Performance Metrics:
Signaling message processing delay
• ts = signaling message processing delay
• tS0 = the base parameter
• fR = a component dependent of the session load (LR)
• fT = a component dependent of the session (LR) and the signaling load (LT)
Signaling message processing delay
In the edge routers: proportional to the number of sessions
In the core routers: a constant
Rev PA1 10.12.2004 22
Conclusions
•The Intserv type (RSVP-like) per-flow end-to-end signaling brings nothing new when comparing to RSVP
• The message processing times have been estimated to be approximately same (1 ms)
• In the IP multiservice backbones some Intserv over DiffServ approach, such as RMD, could be the solution
• The message processing time in the core routers is approximately 5 microsec.• The system bottleneck is the signaling load on the edge routers
• There’s only approximately 0,9 msec time to process one reservation message in the edge router
• The link utilization is the same than with per-flow reservations• The response time is lower because of the sender-oriented approach
Rev PA1 10.12.2004 23
Conclusions (continued)
• NSIS in itself has failed to meet its design criteria:• It is not simple and ligthweight -> It is too modular• There is a serious risk that NSIS will become only one signaling
protocol amoung others
• Too much politics involved in the protocol design work
• The router vendors are not actively participating the work -> the possibility to implement NSIS in networks is dependent of the router implementation
Rev PA1 10.12.2004 24
Future research
• Router vendors’ interests• NSIS(RMD) / RSVP(RMD) with MPLS-tunnels• DCCP -> the adjustment of voice codecs with network
congestion, ECN marking
Rev PA1 10.12.2004 27
Dynamic Provisioning Methods in the Media Gateway
• Measurement Based Admission Control (MBAC)+ CAC is fast+ no extra signaling load+ implementation costs low- cannot guarantee anything- the measurement result arrives always too late
• Probing+ no actual traffic will be lost- additional traffic -> the probe packets can overload the network- Setup delay - the routers do not support ?
• Bandwidth Broker (BB)+ high utilization- complex new node in the network
Rev PA1 10.12.2004 28
RSVP vs. RMD PerformanceRSVP NSIS (RMD)
Response time
(bi-directional)
1 – 1.5 RTT 0.5 – 1 RTT
Processing time < 1 ms Edge: < 1ms
Int.: < 5 s
Link utilization ~100% ~100%
Scalability limited yes
Cost High processing capacity is required in
each nodes
Edge nodes: same as for RSVP
Int. nodes: simple functionality
Source: A. Bader et al.:Presentation in the 11th International Telecommunications Network Strategy and Planning Symposium (Networks2004)