This document discusses scheduling and quality of service (QoS) in advanced telecommunication networks. It covers several key topics in 3 sentences: It describes different scheduling techniques like FIFO, priority queuing, and weighted fair queuing that can provide class-based differentiation for real-time and non-real-time traffic. Buffer management techniques like head of line blocking, partial buffer sharing, and push out buffer are discussed. The document also covers QoS standards from the IETF like RSVP for signaling, integrated services for per-flow reservations, and differentiated services for class-based forwarding behaviors.

1. Scheduling and Quality of
Services (QoS)
Advanced Telecommunication Network
(ET5187)
by
Aris Cahyadi Risdianto
23210016

2. Scheduling and QoS
Input ===> Scheduling and QoS ===> Output
(Controller)

3. Packet Classification
• Same Class / No Class differentiation
> FIFO/LIFO
> Most Common Used
• Different Class
> Lost Sensitive and Delay Sensitive
> Different rules for different Class

4. Queuing System
I = class of service of K and J flows
Mi(t) = actual service allocated for class i at t time
Ni(t) = Buffer size

5. Loss Sensitive Scheduling
Two different Class (High and Low), for the each
same class use FIFO with K buffer
• Head of line (HoL)
• Partial Buffer Sharing (PBS)
• Push Out Buffer (POB)
• Random Early Detection (RED)

6. Buffer Size
Familiar and Famous for ATM network
D* = Delay constraint end to end (Based on ITU) ->
10 ms
E(H) = average number hops ( <10)
M = maximum service rate for STM-1 155 Mbps =
366800 cells
K <= M x D*/10 ms
K small, assured delay but loss cell

7. Head of Line
• Known as priority queue for queueu > 2
• Always served High priority cells in the buffer
• pre-emptive and non pre-empetive
H3 | L5 | L4 | H2 | L3 | H1 | L2 | L1 => HoL
Same as :
L5 | L4 | L3 | L2 | L1 | H3 | H2 | H1 => FIFO

8. Partial Buffer Sharing
• The rule specified by threshold T in the queue
• Nq(t) is number cells/packet at the time T
• Nq(t) < T, high and low enter the queue
• Nq(t) > T, only high enter the queue
• Nq(t) = K, buffer is full, arriving cells discarded

9. Push Out Buffer
• Avoid complex determination of best position
• Only operates when the buffer is full
H3 ==> | L5 | L4 | H2 | L3 | H1 | L2 | L1
LIFO FOB R FOB FIFO FOB

10. Random Early Detection (RED)
• Like PBS but have 2 threshold Tmin and Tmax
• q < Tmin => no packet drop
• q > Tmax => all packet are dropped
• Tmin < q < Tmax => packet are drop with P = (q-
Tmin) * Pmx / Tmax-Tmin
• used for TCP flows congestion avoidance
• variant of RED is WRED (Weighted RED)

11. Delay Sensitive Scheduling
• Assumption there is no problem of losing packet
and buffer k is long
• Consist of processor sharing example WRR has
class k with weight Wk
• WRR (Processing sharing) inflexible because Wk
independent
• Processing rule rather than processing sharing

12. Upper Bound Method
• Used for solving CAC (Call Admission Control)
problem
• Some assumption :
o Each arrival process satisfies with certain
business constrain
o Service time for cell/packet is deterministic and
proportional
o Scheduling rule is used to generate QoS for
class k with minimal Mk ("fair" rule to prevent
blocking another class getting served)

13. Upper Bound Method (Cont.)
• Queue count is maximum difference between
inflow and outflow (λk and μk)
• If queue > 0, class served by minimal rate (μk)
• Number of queue bounded by burstinest σk
provided if λk ≤ μk
• Buffer size bounded by sum of burstinest all flows,
so loss can be guaranteed
• Maximum delay bounded by burstinest divide by
inflows, so delay can be guaranteed

14. Upper Bound Method (Cont.)
• Remarks on upper bound method :
• Zero packet loss only guaranteed for admitted
packet (satisfied with burstinest constrain), if
not packet will be lost
• Delay guaranteed are deterministic because all
stochastic assumed to be bounded or
deterministic
• Upper Bound Method more optimal than N*D/D/1
queuing for scenario where N not identical and
independent CBR resources

15. QoS (Quality of Services)

16. Evolution and Importance
• Internet and Value Added Services is the main
driver
• Internet used for e-commerce, self backing and
communication
• Overall result : people are tolerant about QoS, in
certain point some people are frustrated of losing
data
• Mature Internet need to offer ubiquitous
inexpensive, and high quality services

17. QoS as Technological Lever
• Two Main Approach :
o Over Installing resources (less than 30% load)
o Controlling Traffic in the network to ensure each
flows achieve certain level of QoS
• QoS implementation is faster and cost effective
than expanding new network (Fiber, equipment,
etc)

18. QoS as Commercial Lever
• Old view: over dimension network without
complex network functionality
• Notation QoS : demand always beyond supply
cause congestion
• QoS offer dividing resources, not guarantee
quality (lower priority users get less, high priority
users get more)
• Controlling QoS = Controlling Resources
• Sub-optimal controlling resource = loss revenue

19. Definition and Property of QoS
• In general, QoS express set of service example
performance, availability, reliability and security
• Network QoS on layer 3 (inspired by ATM
network)
• Application Layer QoS associate with GoS
• QoS provision cause dichotomy “soft” and
“hard guarantee”
• Perceived QoS (Voice, Streaming, e-games):
delay, jitter, echo, packet loss

20. Challenges : QoS aware Networking
• Main Problem : Stochastic arrival process and
deterministic set of traffic or determination
• Analysis and computing random variable more
complex
• Computation level explode state spaces and
prevent accurate computations
• Inherent problem “connection set-up time” need
QoS per flow such as QoS routing, signalling and
CAC
• Two different future QoS by IETF : IntServ and
DiffServ

21. Evolution Network Architecture : IP and ATM
• Two different approach : IP by IETF and ATM by
ATM forum
• Layered routing : IP for L3 and ATM for L2
• Integration :
• Partially Integrated : Dual-Mode
• Fully Integrated : I-PNNI
• Ipsilon : ATM for forwarding, IP for control
• IETF : MPLS (IP Fast Switching)
• ATM goal, reality of IP : Basic Architecture for
Broadband Multimedia

22. QoS Emerging in the Internet
• QoS aware networking including QoS routing,
signaling and traffic management
• Standardized by IETF but not implemented
• QoS aware Internet:
• RSVP : signaling
• IntServ : end-to-end signaling per flow basis
• DiffServ : no end-to-end signaling per flow

23. RSVP
• RSVP (Resource Reservation Protocol)
• IETF signalling protocol based on multicast
• Used two types of messages : path and reservation
messages
• Most of Telecom or connection oriented based on
unicast
• Continued with SIP protocol as application layer
signalling protocol

24. RSVP Messages
• Path messages : previous hop IP address, sender
template and IP address, traffic characteristic, end
to end QoS requirement
• Teardown Messages : Path Tear and Resv Tear
o Path Tear : Iniated by the sender to install
reservation state
o Reservation Tear : Travels from receiver to the
sender to remove reservation state

25. RSVP Operations
• Sender send path message to receiver of the
mcast group, each router install the reservation
state and record the hop
• Receiver send "Resv Message" to nearest router
and ask amount of resources
• Nearest Router reserve along the path to the
sender
• If other receiver joint the mcast group, nearest
router ask more resource along the path

26. Characteristic of RSVP
• Used for unicast and multicast application
• Receiver Oriented : flows initiated and resources
reservation
• Consist of policy control and admission control
• MPLS LDP is alternate to RSVP based on explicit
routing
• QoS state is soft state : messages are flows
periodic to adopt the routing changes
• reservation for unidirectional data flows

27. Integrated Services (IntServ)
• Additional component : packet classifier, scheduler
and admission control
• Required resources reservation for each
session/flows using RSVP
• If RSVP failed, the session will be best effort (BE)
• Two class:
o Guaranteed Services : provide services with
guaranteed both delay and bandwidth
o Controlled-Load Services : provide data flow all
same in the unloaded network, and using CAC if
network is loaded

28. Differentiated Services (DiffServ)
• Threat each class differently on per-hop behaviour
(PHB)
• Class differentiation rather than flow differentiation
(more scalable)
• Provide QoS more natural than IntServ which inline
with Internet
• Bandwidth Broker use to managed inter-domain
resources for providing end-to-end QoS

29. Differentiated Class
• IP DSCP format:
• Two different PHB Class, except BE (Best Effort) :

Expedited Forwarding (EF) = virtual leased line or
point-to-point connection

Assured Forwarding (AF) = better best efforf

30. Next on "Scheduling"
• Generalized Processing Sharing (GPS)
• Generalized cu-rules (Dynamic Scheduling
Rules)

31. Next on "Quality of Services"
• Shortcut Routing : L2 over L3 (MPLS)
• Multiprotocol Label Switching (MPLS)
including GMPLS (Generalized MPLS)