Signaled Provisioning of the IP Network
Resources Between the Media Gateways
in Mobile Networks
Leena Siivola
10.12.2004
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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
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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.
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The functional architecture of the 3G network
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The Call Admission Control Mechanism
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Provisioning Methods in the IP Multiservice Backbone
.
.
MBAC = Measurement Based Admission Control
MPLS = Multiprotocol Label Switching
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Static Provisioning Methods in the Media Gateway
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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.
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The NSIS Signaling Framework
NSLP = NSIS Signaling Application Level
NTLP = 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.
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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
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NSIS(RMD) Architecture
It 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
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Successful Reservation
Initiator
Edge
Interior Interior
Edge
Receiver
Resv(QSpec)
Resv(E2E ignore, QSpec)
Resv(LQSpec)
Resv(LQSpec)
Resv(LQSpec)
Resv(QSpec)
Response
Response
Response
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One Possible Implementation of NSIS to the 3G
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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?
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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
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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
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Per-Reservation Performance Metrics:
Signaling Bandwidth Overhead
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Per-Reservation Performance Metrics:
Abortive Provisioning
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Per-Reservation Performance Metrics:
Blocking Probability
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Per-Reservation Performance Metrics:
Reservation Setup Time
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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
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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
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Future research
• Router vendors’ interests
• NSIS(RMD) / RSVP(RMD) with MPLS-tunnels
• DCCP -> the adjustment of voice codecs with network
congestion, ECN marking
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THANK YOU!
• Any questions?
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ADDITIONAL INFORMATION
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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
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RSVP vs. RMD Performance
RSVP
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)
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