Transcript Scheduler

Session 1806
Introduction to QoS
Mechanisms
Networking Tutorials
Copyright © 2004 OPNET Technologies, Inc. Confidential, not for distribution to third parties.
1806 Introduction to QoS Mechanisms
Session Abstract
QoS (Quality of Service) mechanisms are becoming increasingly popular in current networks. This is mainly due to the
varied type of applications (such as voice, video, real-time streaming data) concurrently using the network. These
applications typically require different levels of performance in terms of loss, delay, and throughput.
This tutorial provides a theoretical overview of the basic functional blocks used to provision QoS in different networks
(call admission, policing, shaping, scheduling, etc.). Details of each function and how it is being deployed in IP, ATM,
Frame Relay, and UMTS are provided.
This session is a technology tutorial and is not a tutorial on the use of OPNET products.
This session serves as a technology primer for intermediate-to-advanced QoS sessions:
1310 Planning, Analyzing, and Optimizing MPLS TE and FRR Deployments
1315 Planning and Analyzing QoS Deployments
1510 Understanding IP Model Internals and Interfaces
1813 Traffic behavior and Queueing in a QoS Environment
Copyright © 2004 OPNET Technologies, Inc. Confidential, not for distribution to third parties.
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1806 Introduction to QoS Mechanisms
Outline
 Introduction to QoS
 History
 QoS Definitions
 Basic Functional Blocks of QoS
 Call Admission
 Resource Reservation
 Policing/Shaping
 Scheduling
 Congestion Avoidance Mechanisms
 Protocols Using QoS
 IP: DiffServ, IntServ, DS-MPLS-TE
 ATM
 Frame Relay
 UMTS
 Summary
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1806 Introduction to QoS Mechanisms
 The Best Effort Paradigm:
 Increase in traffic leads to degradation of service
for all. Some applications are impacted more than
others.
 Why not just over-provision resources? Everyone
can then get the best quality all the time…
 The QE curve and its implications
 Do we need QoS?
Quality (Q)
Introduction – Quality of Service (QoS)
QE=C
Efficiency (E)
 Users will find new applications that will eventually cause bandwidth to be a
limiting factor (Murphy’s Law!)
 Relative misuse of available bandwidth by protocols with no throttling
mechanism (such as UDP) over others that do (TCP) may incorrectly
penalize conforming flows
 Conclusion:
 We may need QoS mechanisms for guaranteed services across the network
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1806 Introduction to QoS Mechanisms
QoS – Definition(s)
 Definition
 The end-to-end perspective (We, the users)
QoS is a quantification of service/application-relevant measures of
network effectiveness against acceptable levels for measures such as:
 delay
 jitter
 loss
 response time
 throughput
 QoS – The Network architecture perspective (We, the providers)
 Provide services to specific traffic classes such that QoS can be
provided to end-users on a guaranteed/differential basis
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1806 Introduction to QoS Mechanisms
The QoS Perspective
 So, what is Quality of Service?
 Ability to provide better service to selected traffic
 Distinguish traffic with strict timing requirements
 Allocate resources in the network (e.g., bandwidth, buffer, priority)
so that traffic gets to destinations quickly and reliably
 Do not create bandwidth – simply manage it effectively to meet
application requirements
 Benefits of using QoS
 Dedicated bandwidth
 Controlled network latency and jitter
 Improved loss characteristics
 Control and predictability beyond the “best-effort” concept
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1806 Introduction to QoS Mechanisms
Quality of Service Heterogeneity
QoS-Enabled
Applications
RSVP
Diffserv
Application
Application
Presentation
Presentation
Session
Session
Transport
Transport
RSVP
Diffserv,
MPLS, ATM
Network
Network
RSVP
Diffserv,
MPLS, ATM
Transport
Network
Data Link Layer
Data Link Layer
Data Link Layer
Physical
Physical
Physical
QoS-Enabled
Applications
RSVP
Diffserv
End-to-End Quality of Service Guarantee
RSVP
Diffserv,
MPLS
Other Guaranteed
Approaches
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RSVP
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1806 Introduction to QoS Mechanisms
Outline
 Introduction to QoS
 History
 QoS Definitions
 Basic Functional Blocks of QoS
 Call Admission
 Resource Reservation
 Policing/Shaping
 Scheduling
 Congestion Avoidance Mechanisms
 Protocols Using QoS
 IP: DiffServ, IntServ, DS-MPLS-TE
 ATM
 Frame Relay
 UMTS
 Summary
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1806 Introduction to QoS Mechanisms
Basic Functional Blocks of QoS
 Pieces of the Puzzle
 Call Admission/ Resource Allocation
 SLA (Service Level Agreement)
 Advertisement of required bandwidth by user to the network
 Provisioning of bandwidth by network for user
 Flow Classification
 Ability of the network to identify incoming packets (flows) and assign them a
pre-defined level of service
 Policing and Shaping
 Ability of the network to monitor flows to ensure conformance to advertised
traffic characteristics and provisioned resources
 Congestion Avoidance Mechanisms
 Ability to monitor buffer utilization levels and regulate flow rates to alleviate
congestion on network links
 Scheduling Mechanisms
 Queueing mechanisms to provision differing levels of service
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1806 Introduction to QoS Mechanisms
Call Admission
 Control Plane
 Signal the network on type of
connection and QoS requirements
 Network is responsible for pro-active
Bandwidth Management
 Establishing the route of the
connection
 Reserving enough resources to
meet QoS requirements
 Stochastic reservation
 Virtual pipes
 Rejecting a call if it does not have
enough resources to meet the call
 Examples:
 ATM
 IntServ (RSVP)
 MPLS
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2
2
3
3
4
2
1
Request
2
Route Establishment
3
Confirmation
4
Acknowledgement
1
Source
Destination
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1806 Introduction to QoS Mechanisms
Flow Classification
 Need a method to identify packets/cells in order to provide differential
treatment
 Examples of Classification Criteria
 VC number
 MPLS Label
 Type of Service
 Protocol
 Address
 Source IP Address
 Destination IP Address
 Port Number
 Source port
 Destination port
 Incoming interface
 DSCP (DiffServ Code Point)
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C
L
A
S
S
I
F
I
E
R
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1806 Introduction to QoS Mechanisms
Policing and Shaping
 Regulate the rate at which a flow is allowed to inject packets
into the network
 Using an appropriate time scale for measurement is important
for three metrics
 Average rate
 Limit the long term-average rate (packets per time interval) of the flow
 Peak rate
 Limit the maximum number of packets that can be allowed into the
network over a short interval of time
 Burst size
 Limit the number of packets that can be allowed into the network over
an extremely short interval of time
 Limiting case (as time interval approaches zero) defines the number of
packets that can be instantaneously sent into the network
 Systems use either a leaky bucket or a token bucket mechanism
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1806 Introduction to QoS Mechanisms
The Bucket Mechanism
r tokens/second
Size b
Packets
Remove
Token
To network
Data Stream
Buffer
Single token bucket mechanism
 Consists of a bucket (of size b) that can hold up to b tokens which are created at a rate of r
tokens/second
 New tokens either get added to the bucket or are discarded (if bucket is full)
 Tokens do not get stored in case of no packets (Leaky Bucket)
 Tokens get stored awaiting packets (Token Bucket)
 An incoming packet must remove a token from the token bucket before entering the
network
 Lack of tokens in the bucket could cause packet
 To be dropped (a simple policer)
 To be buffered (delayed) as it awaits a token (a shaper)
 Single bucket allows for flow to be policed based on average rate metric
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1806 Introduction to QoS Mechanisms
Dual Buckets
r tokens/second
p tokens/second
Size b2
Size b1
Packets
Remove
Token
Remove
Token
To network
Data Stream
Buffer
Dual token bucket mechanism
 Mechanism
 Consists of a two token buckets
 Allows for policing on average rate, peak rate, and burst size
 Parameters of buckets are set based on flow requirements
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1806 Introduction to QoS Mechanisms
Policing and Shaping
Traffic Rate
Policing
Traffic
Traffic
 Effect of Policing
Traffic Rate
Time
Shaping
Time
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Traffic
Traffic
Time
 Effect of Shaping
Traffic Rate
Traffic Rate
Time
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1806 Introduction to QoS Mechanisms
Congestion Avoidance
 Not congestion management!
 Monitor traffic loads at egress network interfaces in order to anticipate and
avoid congestion in the buffers
 Do not accept packet into buffer if packet fails “discard test”
 Typically works best in tandem with TCP
 Take advantage of TCP retransmission mechanism by randomly dropping
packets
 Reduce chance of tail drop
 Minimize chance of global synchronization
 Common schemes
 RED (Random Early Detection)
 Stochastically drop packets as congestion begins to increase
 WRED (Weighted Random Early Detection)
 Combine stochastic dropping of packets with IP Precedence
 Implemented by two different algorithms
 Average queue size computation
 Packet drop probability
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1806 Introduction to QoS Mechanisms
Congestion Avoidance – WRED
Discard packets based on: Manage Interface
-Average queue depth
Buffer Resources
-Type of Service (TOS)
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Avoid Congestion on Links
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1806 Introduction to QoS Mechanisms
Congestion Avoidance – RED
Packet
Dropped
Packet Randomly Dropped
Packet
Enqueued
Dropping
Prob.
100%
100/Mark Prob.
0%
Average
queue size
Maximum
Threshold
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Minimum
Threshold
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1806 Introduction to QoS Mechanisms
Scheduling
 Common queueing disciplines
 FIFO (First In First Out)
 PQ (Priority Queueing)
 Strict
 WRR (Weighted Round Robin) variants
 FQ (Fair Queueing)
 Equal weight given to each queue
 WFQ (Weighted Fair Queueing)
 Variable weight given to each queue
 Approximate when packet sizes disparate
 Implemented in software
 CQ (Custom Queueing)
 CBWFQ (Class Based Weighted Fair Queueing)
 WFQ where packets are classified into queues
 DRR (Deficit Round Robin)
 More exact weight given to each queue
 Implemented in hardware
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1806 Introduction to QoS Mechanisms
Scheduling – PQ
Classification by:
-Type of Service
-Protocol
-IP address
-Incoming interface
-Port number
Manage Interface
Buffer Resources
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Allocate Link Bandwidth
by Source Priority
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1806 Introduction to QoS Mechanisms
Scheduling – WFQ
Classification by: Manage Interface
-Type of Service Buffer Resources
-Protocol
-IP address
-Incoming interface
-Port number
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Allocate Fair Proportion of Link
Bandwidth
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1806 Introduction to QoS Mechanisms
Scheduling – WFQ Principles
 Operational basics
 Divide traffic into various queues
 Assign a weight (portion of bandwidth) to each queue
 Serve each queue according to its weight (in essence, desired percentage
of output port bandwidth for the queue)
 Each class is “guaranteed” a minimum share of output forwarding
capacity
 Note that the queues are not in a priority order – which means each
queue sees the full server for a fraction of the total time
 Allows for configuration of multiple levels of sharing hierarchy
 LLQ (Low Latency Queue):
 Strict priority queue within CBWFQ paradigm
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1806 Introduction to QoS Mechanisms
Putting the Pieces Together…
Conforming
Meter
Nonconforming
Packets
Packets
Packets
Classifier
Marker
Shaper/
Dropper
Shaped
Packets Congestion
Avoidance
Scheduler
Dropped
Packets
 Classifier: Selects packets based on portions of packet header
 Marker: Marks/Remarks the packet header based on traffic class
 Meter: Checks compliance to traffic profile and passes result to Marker and
Shaper/Dropper
 Shaper: Allows for delaying of packets in buffer to enforce compliance with
traffic profile
 Dropper: Drops traffic that does not conform with traffic profile
 Congestion Avoidance: Checks buffer levels and stochastically drops packets
 Scheduler: Allows for differential queueing and servicing of packets
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1806 Introduction to QoS Mechanisms
Outline
 Introduction to QoS
 History
 QoS Definitions
 Basic Functional Blocks of QoS
 Call Admission
 Resource Reservation
 Policing/Shaping
 Scheduling
 Congestion Avoidance Mechanisms
 Protocols Using QoS
 IP: DiffServ, IntServ, DS-MPLS-TE
 ATM
 Frame Relay
 UMTS
 Summary
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1806 Introduction to QoS Mechanisms
Scope of IP QoS
 From a TCP/IP perspective …
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1806 Introduction to QoS Mechanisms
IP Datagram Lifecycle under QoS
OUTGOING
QUEUE
INCOMING
ROUTING
Band. Management CLASSIFICATION
Band. Management
Classify and “police”
datagrams at
interfaces. Defines
policies for handling
traffic – e.g., setting
TOS, special
handling when it
exceeds thresholds.
Based on:
- IP Precedence
- Application Type
- Incoming Interface
Use standard IP
routing protocols
(RIP, IGRP,
EIGRP, OSPF,
BGP4, static) to
determine next
hop and interface
to forward the
packet
Congestion
Avoidance
SCHEDULING
Classify and place
Discard packets
incoming datagrams in if they do not
appropriate queues.
conform to
Based on:
agreed policies.
- IP Precedence
Policies can be
- Application type
defined using
- Application port
RED/WRED
- Incoming Interface
- Source/dest address
- DiffServ code point
- Combination of above
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Performs
datagram
scheduling by
using a specified
queuing scheme.
Options are:
- CQ
- PQ
- FIFO
- WFQ
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1806 Introduction to QoS Mechanisms
DiffServ Basics
 Focus on QoS provisioning across single domain and not end-to-end
 Classification/Policing at the edge and “class-based” forwarding in the core
 Use of IP ToS byte for DSCP (DiffServ Code Point)
 Allocate resources for aggregated traffic (Not individual flows)
 Emphasis on guaranteeing QoS by provisioning (SLA- Service Level
Agreement) rather than reservation (signaling)
 PHB (Per Hop Behavior)
 “Externally observable forwarding treatment at a single node for an aggregate
of flows with the same DSCP value.”
 Standard PHBs
 EF (Expedited Forwarding) for low delay, low jitter requirements
 AFxy (Assured Forwarding) for differential treatment. Allows for four classes
(0 < x < 5) and three levels (0 < y < 4) of drop precedence
 BE (Best Effort)
 Allows for backward compatibility with IP ToS precedence values
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1806 Introduction to QoS Mechanisms
DiffServ Components
 At the edge of DiffServ domain
 Classification and Marking
 Policing/Shaping
 Within the core of the DiffServ domain
 Congestion Avoidance
 Scheduling
 Combination of LLQ / CBWFQ for differential treatment to
DiffServ Classes (Why do we need LLQ?)
 Result:
 Provide differential treatment to Behavior Aggregates (BA) by proper
configuration
 Remove complexity from core of network and place it at edges
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1806 Introduction to QoS Mechanisms
IntServ
 Allow for per-flow QoS
 More state information to be maintained (resource intense)
 Mechanism
 Applications announce traffic request
 Nodes use signaling and connection admission to establish route
 Accept the call; reserve resources for call along path
 Reject the call
 Nodes use policing mechanisms to enforce traffic profiles
 Features
 Provision true end-to-end QoS on a per-flow basis
 Routers need to maintain state information on a per-flow basis
 Scalability issues within core of network
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1806 Introduction to QoS Mechanisms
RSVP
 RSVP (Resource Reservation Protocol)
 Protocol used for control signals
 Transmitting applications use RSVP to describe data traffic
characteristics
 Receiving applications use RSVP to describe their QoS requirements
 Network Elements use RSVP to deliver QoS requests to other network
elements
 Reservation setup mechanism
 Dynamic: applications can dynamically reserve and free network
bandwidth
 Simplex reservation setup: Each side of a connection requiring
bandwidth guarantee must perform a separate reservation procedure
 Hop-by-hop reservation style: Every RSVP-aware hop benefits from
the RSVP messages traversing a flow – end-to-end guarantee not
possible if some intermediate elements do not support RSVP
 Different reservation styles for unicast and multicast traffic
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1806 Introduction to QoS Mechanisms
RSVP Usage Options
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1806 Introduction to QoS Mechanisms
MPLS – Basics
 Label Switching
 Originally designed to make routers faster
 Longest prefix lookup vs. fixed label lookup
 Separates control and data plane
 Higher forwarding rates
 Enables traffic engineering
 Scalable, high-performance IP networks
 Multi-Protocol
 “Label” as universal identifier
 Single device can transport data units of multiple protocols
 E.g., IP datagrams and ATM cells through an ATM switch
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1806 Introduction to QoS Mechanisms
MPLS – Traffic Engineering
 Traffic Engineering is placing traffic where there is bandwidth
 Optimize network resources through careful distribution of
traffic in network
 Provide ability to arbitrarily segregate flows at any desired
level of granularity and route those flows independently from
one another
 Constraint Based Routing (CBR)
 Allow TE Cost Metric to be based on parameters such as
 Hop Count
 Delay
 Available Bandwidth
 TE Cost
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1806 Introduction to QoS Mechanisms
MPLS-TE Operation
 Optimize route selection of LSP based on TE metric
 Off-Line Mode
 Compute routes periodically (using CBR) and switch to new routes during
maintenance periods
 Could lead to operational delays as all routes (even existing demands) are reestablished
 On-Line Mode
 Route computation performed incrementally with arrival of each new demand
 Does not require rerouting of existing traffic
 Inefficient optimization as compared to Off-Line Mode
 Two modes can be combined at different time scales
TCP Traffic
UDP Traffic
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1806 Introduction to QoS Mechanisms
DiffServ Aware MPLS-TE
 Combine TE concept of routing with service provisioning concept of
DiffServ
 CBR
 New concept of sub pools (within the global available bandwidth pool)
 Allows for a more restrictive bandwidth constraint that can be used by
LSPs meant for “guaranteed” traffic
 Allow LSPs to request bandwidth from a specific sub pool
 Concept of ensuring QoS for flows
 Forward Equivalence Class (FEC)
 A set of classification rules to allow classification of packets
 Examples: IP Prefix, Egress Router, Application flow
 Use Marking functionality to map FEC onto MPLS header
 E-LSP
 EXP bits on MPLS header are used to carry information about FEC
 L-LSP
 MPLS Label contains information about FECs
 Map EXP classes to DiffServ PHB for specific scheduling policies
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1806 Introduction to QoS Mechanisms
Outline
 Introduction to QoS
 History
 QoS Definitions
 Basic Functional Blocks of QoS
 Call Admission
 Resource Reservation
 Policing/Shaping
 Scheduling
 Congestion Avoidance Mechanisms
 Protocols Using QoS
 IP: DiffServ, IntServ, DS-MPLS-TE
 ATM
 Frame Relay
 UMTS
 Summary
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1806 Introduction to QoS Mechanisms
ATM Service Classes
Class
Description
Example
CBR
RT-VBR
NRT-VBR
Constant Bit Rate
Variable Rate: RT
Variable Rate: NRT
T1-circuit
Video conf
Email
ABR
UBR
Available Bit Rate
Unspecified Bit Rate
Guaranteed Frame Rate
Browsing
Best effort
IP traffic
GFR
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1806 Introduction to QoS Mechanisms
Usage Parameter Control (UPC)
 Parameters
 Peak Cell Rate (PCR)
 Maximum rate at which the source can send cells
 Sustainable Cell Rate (SCR)
 Upper-bound on average cell rate
 Maximum Burst Size (MBS)
 Maximum number of cells sent back to back at PCR
 Minimum Cell Rate (MCR)
 Minimum cell rate guaranteed by the circuit
 Cell Delay Variation Tolerance (CDVT)
 The maximum cell delay variance
 QoS metrics
 Maximum Cell Transfer Delay (maxCTD)
 The maximum time spent by a cell in the network
 Cell Delay Variation (CDV)
 Difference between best and worst case CTD
 Cell Loss Ratio (CLR)
 Maximum ratio of lost cells over total cells transmitted
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1806 Introduction to QoS Mechanisms
ATM Classes, UPC and QoS
Class
UPC Contract
QoS Descriptor
CBR
PCR
Max CTD, CDV, CLR
RT-VBR
PCR, SCR, MBS
Max CTD, CDV, CLR
nRT-VBR
PCR, SCR, MBS
CLR
ABR
PCR
CLR (some networks)
UBR
MCR
No QoS
GFR
PCR, MCR
CLR
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1806 Introduction to QoS Mechanisms
Congestion Control in ATM
 Connection Admission Control (CAC)
 Computes an equivalent bandwidth, a function of UPC
 Source checks if enough resource (equivalent bandwidth) is available
before accepting a connection. Routing protocol (PNNI) may be used
 Allocates bandwidth for connection or denies entry
 Congestion Policing
 Controls whether the user (flow) obeys the UPC contract (usually
using a sequence of leaky buckets)
 Control of cell rates
 Using control packets (only applicable to ABR)
 Congestion Avoidance
 Early Packet Discard (EPD)
 Partial Packet Discard (PPD)
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1806 Introduction to QoS Mechanisms
Service Classes for IP Traffic
 Traditionally UBR is used to carry IP traffic over an ATM
network
 UBR offers no QoS and link subscription is minimal (four
cells/second), since IP offers no guarantee of service anyway
 GFR (Guaranteed Frame Rate) is a new service class defined
by the ATM FORUM
 UBR with MCR (Minimum Cell Rate) and EPD/PPD but without the
complicated renegotiation of the MCR rate of the ABR class
 If GFR is not available, nRT-VBR is a valid option, provided
AAL5 (ATM Adaptation Layer 5) and EPD/PPD are used
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1806 Introduction to QoS Mechanisms
ATM: Congestion Avoidance
 Early Packet Discard (EPD)
 Maximize the number of complete AAL5 frames that are successfully
transmitted during periods of congestion
 On reaching a threshold value in the ATM switch buffer, cells
belonging to new AAL5 frames are discarded
 Implemented on selected virtual circuits
 Enforced before cells are admitted into the buffer
 Partial Packet Discard (PPD)
 If a cell of a AAL5 frame needs to be discarded, then all remaining
cells of that frame are also discarded except for the last one that
contains the AAL5 trailer
 Enforced after cells are admitted into the buffer
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1806 Introduction to QoS Mechanisms
QoS Protocols – A Comparison
QoS
Protocols
ATM
DiffServ
IntServ
Connection
Admission Control
Required
Not Required
Required
Control Plane
Protocol
PNNI,
H-PNNI
Use existing
routing
RSVP
Policing/Shaping
Required
Optional
Required
Classification
UPC parameters
map to service
class
Src/Dest IP
Address etc.
RSVP state
information, same as
DiffServ
Congestion
Avoidance
EPD, PPD
RED, WRED
variants
RED, WRED, variants
Scheduling
WRR based
LLQ/CBWFQ,
WDRR etc.
Same as DiffServ
QoS
End-to-end at ATM
Layer
Within core of
domain (IP Layer)
End-to-end
(Application Layer)
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1806 Introduction to QoS Mechanisms
Outline
 Introduction to QoS
 History
 Basic Functional Blocks of QoS
 Call Admission
 Resource Reservation
 Policing/Shaping
 Scheduling
 Congestion Avoidance Mechanisms
 Protocols Using QoS
 IP: DiffServ, IntServ, DS-MPLS-TE
 ATM
 Frame Relay
 UMTS
 Summary
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1806 Introduction to QoS Mechanisms
Frame Relay
 Policing/Shaping
 Mainly used to control traffic flows in a hub-and-spoke network
 Used to throttle amount of traffic on a VC
 Can be used with ECN (Explicit Congestion Notification)
 FECN (Forward ECN)
 BECN (Backward ECN)
 Congestion Avoidance Schemes
 Partial Packet Discard (PPD)
 Early Packet Discard (EPD)
Copyright © 2004 OPNET Technologies, Inc. Confidential, not for distribution to third parties.
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1806 Introduction to QoS Mechanisms
Outline
• Introduction to QoS
– History
• Basic Functional Blocks of QoS
– Call Admission
– Resource Reservation
– Policing/Shaping
– Scheduling
– Congestion Avoidance Mechanisms
• Protocols Using QoS
– IP: DiffServ, IntServ, DS-MPLS-TE
– ATM
– Frame Relay
– UMTS
• Summary
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46
1806 Introduction to QoS Mechanisms
QoS in UMTS
 QoS Mechanism
 Connection Admission (Frequency Allocation)
 Inter-operability with wired networks. Allows for mapping precedence
bits in IP ToS byte (or service classes from ATM network) to one of
UMTS traffic classes
 Characterizes higher layer traffic for UMTS
 Each traffic class has its own configuration
 Allows configuration of data rate, block error rate, transfer delay, etc.
 Allocation, retention and preemption details for use during admission
control phase can also be configured
 UMTS QoS Classes
 Based on 3G TS 23.197
 Conversational
 Streaming
 Interactive
 Background
Copyright © 2004 OPNET Technologies, Inc. Confidential, not for distribution to third parties.
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1806 Introduction to QoS Mechanisms
Outline
• Introduction to QoS
– History
– QoS Definitions
• Basic Functional Blocks of QoS
– Call Admission
– Resource Reservation
– Policing/Shaping
– Scheduling
– Congestion Avoidance Mechanisms
• Protocols Using QoS
– IP: DiffServ, IntServ, DS-MPLS-TE
– ATM
– Frame Relay
– UMTS
• Summary
Copyright © 2004 OPNET Technologies, Inc. Confidential, not for distribution to third parties.
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1806 Introduction to QoS Mechanisms
IP QoS Framework
Source: Cisco “Service Provider QoS – Providing e2e Guarantees, April 2001
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1806 Introduction to QoS Mechanisms
ATM QoS Approaches
 Tailored Service Classes defined for use for specific QoS
expectations
 UPC parameters defined for service classes
 Connection and establishment of routes dictated by
equivalent bandwidth calculations
 QoS enforced by token bucket mechanisms and WRR-based
scheduling
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50
1806 Introduction to QoS Mechanisms
Relevant Sessions in OPNETWORK 2003
 Possible follow-up sessions include:
 1310 Planning, Analyzing, and Optimizing MPLS TE and FRR
Deployments
 1315 Planning and Analyzing QoS Deployments
 1510 Understanding IP Model Internals and Interfaces
 1813 Traffic behavior and Queueing in a QoS Environment
Copyright © 2004 OPNET Technologies, Inc. Confidential, not for distribution to third parties.
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1806 Introduction to QoS Mechanisms
Common Acronyms
AF<xy>
ATM
BA
BE
CAC
CBQFW
CBR
CBR
CQ
Diffserv
DRR
DSCP
ECN
EF
EPD
FEC
FIFO
IntServ
Assured Forwarding Class
Asynchronous Transfer Mode
Behavior Aggregate
Best Effort Class
Connection Admission Control
Class Based WFQ
Constraint Based Routing (MPLS)
Constant Bit Rate (ATM)
Custom Queueing
Differentiated Services
Deficit Round Robin
Diffserv Code Point
Explicit Congestion Notification
Expedited Forwarding Class
Early Packet Discard
Forward Equivalence Class
First In First Out
Integrated Services
Copyright © 2004 OPNET Technologies, Inc. Confidential, not for distribution to third parties.
LSP
LSR
MPLS
TE
PHB
PNNI
PPD
PQ
RED
RSVP
SLA
ToS
UPC
UMTS
VC
WFQ
WRED
WRR
Label Switched Path
Label Switched Router
Multi Protocol Label
Switching
Traffic Engineering
Per Hop Behavior
Private Network to Network
Interface
Partial Packet Discard
Priority Queueing
Random Early Detection
Resource Reservation
Protocol
Service Level Agreement
Type of Service
Usage Parameter Control
Universal Mobile
Telecommunication System
Virtual Channel
Weighted Fair Queueing
Weighted RED
Weighted Round Robin
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1806 Introduction to QoS Mechanisms
References
 QoS
 Y. Bernet, “Networking Quality of Service and Windows Operating Systems,” New
Riders Publishing, 2001. ISBN 1-57870-206-2
 Z. Wang, “Internet QoS – Architectures and Mechanisms for Quality of Service,”
Morgan Kaufmann Publishers, 2001. ISBN 1-55860-608-4
 http://www.cisco.com
 http://www.qosforum.com
 Protocol Standards (http://www.ietf.org/home.html)
 IntServ
 RFC 2208, 2209, 2210, 2211, 2212, 2215, 2216, 2750, 2998, 3006
 DiffServ
 RFC 3140, 3168, 3260, 3246, 3270, 3289
 MPLS
 RFC 3031, 3032, 3034, 3035
 MPLS
 http://www.mplsrc.com
 ATM
 http://www.atmforum.com
 Frame Relay
 http://www.frforum.com
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1806 Introduction to QoS Mechanisms
Take-Away Points
 So what is QoS?
 Ability to provide better service to selected traffic
 Functional Blocks of QoS
 Call Admission
 Resource Reservation
 Policing/Shaping
 Scheduling
 Congestion Avoidance Mechanisms
 Protocols that use QoS
 IP (DiffServ, IntServ, MPLS-TE)
 ATM
 FR
 UMTS
 So, what’s next?
 Learn how to configure and deploy QoS in your network
Copyright © 2004 OPNET Technologies, Inc. Confidential, not for distribution to third parties.
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