1 Network Architecture and Design Internet QoS Differentiated Services (DiffServ) Multiprotocol Label Switching (MPLS) Reference Zheng Wang, Internet QoS,

Network Architecture and Design 1

Internet QoS

Differentiated Services (DiffServ) Multiprotocol Label Switching (MPLS)

Reference

Zheng Wang, Internet QoS, Architectures and Mechanisms for QoS, ISBN 1-55860-608-4, 2001.

Network Architecture and Design 2

DiffServ - Overview

Integrated services provides QoS; but Problem of scalability

The routers have to maintain state on every flow passing through them.

Heterogeneous networks may not be able to provide particular QoS controls or even RSVP.

Differentiated service (DiffServ) aims to offer QoS to aggregated flows.

Network Architecture and Design 3

DiffServ - Overview DiffServ defines Differentiated Service Code

Point (DSCP) in IPv4 TOS field, IPv6 Traffic Class field.

All traffic in one DSCP is treated the same. Per hop behaviour (PHB) is determined by

DSCP of packet. Service Level Agreements concern aggregate

traffic not individual flows.

Network Architecture and Design 4

DiffServ - Operation

classifier marker

meter

Shaper/dropper

To interiornodesInput

Network Architecture and Design 5

DiffServ - Traffic conditioning Classifier

Marks packets according to classification rules. Meter

Checks whether the traffic falls within the negotiated profile.

Marker Marks traffic that falls within profile.

Shapper/DropperDelays and then forwards, discards, or remarks traffic.

Network Architecture and Design 6

DiffServ - Operation

2-Bit Differentiated Services Architecture for the Internet Premium service

Premium service levels are specified as a desired peak bit rate for a specific flow

Assured service Best-effort service

Network Architecture and Design 7

DiffServ - Operation Like leaky bucket with 2-bit designators (not just CLP setting). By

software not built into hardware. In-profile traffic is marked:

A-bit is set in every packet Out-of-profile (excess) traffic is unmarked

A-bit is cleared (if it was previously set) in every packet; this traffic treated as best-effort

r bps

b bits

metering in-profile traffic

out-of-profile traffic

user profile (token bucket)

set A-bit

clear A-bit

assured traffic

Network Architecture and Design 8

DiffServ - Operation In-profile traffic marked:

Set P-bit in each packet Out-of-profile traffic is delayed, and when buffer overflows it is dropped

r bps

b bits

Metering/Shaper/Set P-bit

in-profile traffic

out-of-profile traffic(delayed and dropped)

premium traffic

user profile(token bucket)

Network Architecture and Design 9

Problems of DiffServ Does not support dynamic reservations only

static. Scalable, but provides weaker services than

IntServ (due to aggregation). It is not yet clear what kind of guarantees can be

given to end-to-end services (how to translate user-QoS to net-QoS?).

Missing of standardized resource management in every node. Solution: Bandwidth Broker (BB)

Network Architecture and Design 10

Bandwidth Broker (BB) The BB performs three distinct tasks:

Negotiation of SLAs with BBs of neighbouring domains Translation of SLAs into one or several Traffic Control Agreements (TCAs)

for edge devices Delivery of the TCAs to the edge routers of the administered domain

Network Architecture and Design 11

IntServ Vs DiffServ

Integrated Services

Differentiated Services

QoS guarantee Per data stream Aggregated data streams

Configuration Per session end-to end

Between domains

Duration of guarantee

Short-lived Long-term

Signaling RSVP Not yet defined

Network Architecture and Design 12

IntServ Vs DiffServ IntServ provides fine grain control and handles

dynamic allocation of resources to flows DiffServ provides course grain control of flows

through their aggregates The two together can be combined to provide

scalable end to end Integrated service, using a DiffServ region as a single element

Controlled Load can be implemented over Assured Forwarding PHB

Guaranteed can be implemented over Expedited Forwarding PHB

Network Architecture and Design 13

IntServ & DiffServ

Network Architecture and Design 14

Internet QoS

Differentiated Services (DiffServ) Multiprotocol Label Switching (MPLS)

Network Architecture and Design 15

MPLS Overview

MPLS (Multiprotocol Label Switching) Improves the forwarding speed of a router. Introduces new capabilities for large IP

networks Introduction of many of the qualities and

attributes of switched networks to IP networks Integrates Layers 2 and 3.

Network Architecture and Design 16

MPLS Operation MPLS Components

Edge-LSR: Edge-Label Switching Router Assigns a label in an incoming IP packet

Removes the label of an incoming IP packet

LSP: Label Switching Path The path that a packet follows in an MPLS network

LSR: Label Switching Router Makes forwarding decisions based SOLELY on the contents of

the label (basic advantage)

Strips off the existing label and applies a new label which tells the next hop how to forward the packet

Network Architecture and Design 17

MPLS – Traditional IP Routing

47.1

47.247.3

IP 47.1.1.1

Dest Out

47.1 147.2 2

47.3 3

1

23

Dest Out

47.1 147.2 2

47.3 3

1

2

1

23

IP 47.1.1.1

IP 47.1.1.1IP 47.1.1.1

Dest Out

47.1 147.2 2

47.3 3

Network Architecture and Design 18

MPLS – MPLS RoutingIntfIn

LabelIn

Dest IntfOut

3 0.40 47.1 1

IntfIn

LabelIn

Dest IntfOut

LabelOut

3 0.50 47.1 1 0.40

47.1

47.247.3

1

2

31

2

1

2

3

3

IntfIn

Dest IntfOut

LabelOut

3 47.1 1 0.50

IP 47.1.1.1

IP 47.1.1.1

Network Architecture and Design 19

MPLS Label Format IP packet is encapsulated in MPLS

header and sent down LSP

IP packet is restored at end of LSP by egress router TTL is adjusted also

…IP Packet

32-bitMPLS Header

Network Architecture and Design 20

MPLS Label format

TTLLabel CoS S

Label Class of service Stacking bit Time to live

Decrement at each LSR, or Pass through unchanged

Network Architecture and Design 21

MPLS Fast forwarding speed Traffic Engineering

constraint-based routing explicit routing ability to compute a path at the source ability to reserve network resources and to modify link

attributes Voice/Video on IP

delay variation + QoS constraints Virtual Private Networks

controllable tunneling mechanism equivalent to a Frame Relay or ATM VC

Network Architecture and Design 22

Second Intermediate Report Multicast Routing (Focus on Internet Technology)

Doukas Multicast Routing (Focus on Wireless Technologies)

Kikilis MBONE

Mavrogenis IntServ (Focus on IntServ Implementation)

Klaoudatou IntServ (Focus on support of IntServ over other

technologies, i.e., ATM, wireless) Barbarousis

Diffserv (Focus on Diffserv Implementation) Ratsiatos

Network Architecture and Design 23

Second Intermediate Report Diffserv (Focus on support of DiffServ over other

technologies, i.e., ATM, DVB) Panoutsakopoulos

Integration of IntServ and Diffserv Lizos

MPLS (Focus on Routing) Kolovou

MPLS (Focus on Admission Control) Baliotis

SLAs/SLSs Rekleitis

Protocols for inter-BB communication Plataniwtis

Network Architecture and Design 24

Second Intermediate Report

Structure Overview of examined technology Focus on open research points Related to open points works - State of the

art behind open points Your own interests - Ideas Conclusions References

Network Architecture and Design 25

Second Intermediate Report

Report (soft and hard copy) A related presentation (about twenty

minutes) Usage of Greek language Deadline: 26/04/03

Network Architecture and Design 26

End of Fourth Lecture