Network layer
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Network layer. Doug Young Suh [email protected] Last update : Aug. 1, 2009. Network layer and realtime multimedia. Protocols for switching in the routers Routing = path + resource cf) direction + width of road IP header : IPv4 and IPv6 New features in IPv6

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Network layer

Network layer

Doug Young Suh

[email protected]

Last update : Aug. 1, 2009

Network Layer


Network layer and realtime multimedia

Network layer and realtime multimedia

  • Protocols for switching in the routers

    • Routing = path + resource

      cf) direction + width of road

  • IP header : IPv4 and IPv6

    • New features in IPv6

  • Best Effort  per-class  per-flow

    • intServ. diffServ, MPLS

MediaLab , Kyunghee University


Qos control for networked video

QoS control for networked video

Upper Layers

(Video Layer)

Error resilience/concealment, scalability coding

End-to-end

UDP/RTP&RTCP, FEC, retransmission

Transport Layer

IP TOS, RSVP, intServ

Network Layer

FEC, retransmission, MAC

Data Link Layer

Power control

Physical Layer

Networked Video


Network layer approaches

Network layer approaches

  • RSVP

  • intServ

  • diffServ

  • MPLS

Video Layer

Transport Layer

  • Over-provision or QoS control?

  • Internet service will be charged.

  • IPv6 doesn't give a solution for the QoS issue. IPv6 has the potential.

Networked Video


Categories of qos protocols

Categories of QoS protocols

Network QoS

  • Packet switching

  • Variable QoS (Best Effort)

  • Resource sharing

  • e.g. downloading data

  • Circuit switching or broadcasting

  • Fixed QoS

  • Dedicated circuit for a call

  • e.g. telephone

  • QoS switching

  • Guarantee reserved QoS

  • Resource allocation (dynamic)

  • e.g. realtime service

QoS switching

Per-class (coarse) : Packets are classified into several classes.

Per-flow (fine) : A flow could be a media stream of a certain service. Call admission control is required for resource reservation with all routers along the path.


Per class and per flow qos services

Per-class and per flow QoS services

Per-class QoS service

router

I’m a class B packet.

You, use the Gate B.

After reading the temporary customer list for identification,,,,,,,

Per-flow QoS service

router

I’m a video packet for the video-phone service between John and Susan.

We provide you QoS of [5Mbps, 10-5 packet loss, and 1ms delay].


Qos identification for every video packet

QoS identification for every video packet

  • per-class QoS : 8 bit TOS (TC) in the IP header

    • BA (behavior aggregate) classifier

    • PHB : EF and AF(4 classes with 3 levels)

  • per-flow QoS

    • Each flow has a temporary contract on QoS.

    • IntServ : identified by 5 tuples

      • 104 bits IPv4, 296 bits IPv6

    • MPLS : identified by label

PHB1

BA

classifier

PHB2

PHB3

intServ routing table

1

SA

DA

SP

DP

Pr

TSpec

2

SA

DA

SP

DP

Pr

TSpec

3

SA

DA

SP

DP

Pr

TSpec

4

SA

DA

SP

DP

Pr

TSpec

5

SA

DA

SP

DP

Pr

TSpec

Admission

control

classifier

label

SA

DA

SP

DP

Pr

data

Packet

scheduler

data


Rsvp intserv

RSVP/intServ

  • CAC by RSVP, call control by intServ


Rsvp parameters

RSVP parameters

  • Tspec (PATH), Rspec (RESV)

    • r : token rate

    • b : token-bucket depth

    • p : peak rate

    • m : minimum policed size

    • M : maximum packet size

  • Leaky bucket model [r,b], [p,M]

Networked Video


Resource reservation

Resource reservation

  • When realtime service needs excess bandwidth, non-realtime service packets are buffered.

Networked Video


Diffserv architecture

Diffserv Architecture

r

b

ER marking

Edge router:

- per-flow service

- marks packets of in- or out-profile

Bandwidth Broker

Core router:

- per class service

- buffering and scheduling

- preference to in-profile packets

- Assured Forwarding

CR scheduling

.

.

.

Networked Video


Er traffic conditioning

ER : Traffic Conditioning

  • Classifier of micro-flow w.r.t. agreed traffic profile

  • Marker : low, medium, high drop precedence

Networked Video


Cr traffic management

CR : traffic management

  • BA (behavior aggregate) classifier

  • PHB

    • EF : guaranteed service, WFQ (weighted fair queuing)

    • AF : 4 classes with 3 levels (high, medium, low drop procedure levels), RED (random early discard)

PHB1

BA

classifier

PHB2

PHB3

Networked Video


History of video network

History of video/network

IPv4

2G

IPv6

3-4G

H.261

MPEG-2

SVC

??

Circuit switching

Broadcasting

per class QoS

Per flow QoS

MPEG-4

& AVC

~AVC

2008

Fine QoS control, each media traffic of each individual service

Packet switching :

Best effort

No QoS control, because everything is fixed.

No QoS control, because network does not care.

Coarse QoS control, [premium, medium, low, etc.]


Revisit qos of upper layers

Revisit QoS of upper layers.

  • Video layer

    • Feedback rate control

      • Realtime encoding : quality vs. bitrate (R-D)

      • Non-realtime encoding : Scalable coding

    • VBR(natural) and CBR(forced rate control)

    • Multiple levels of significance

      • Partition A, B, C in a frame

      • Intra > predictive > bi-directional

      • Scalable coding : base layer > enhancement layers

    • Error propagation and error resilience

  • Transport layer

    • Feedback of QoS metrics : loss/delay/bitrate

    • FEC : UEP/ULP (unequal error/loss protection)

MediaLab , Kyunghee University


Ipv6 ipng

IPv6 (IPng)

  • 128 bit address => 181018nodes, 4 nodes/cm2

    • Ubiquitous networks

    • Hierarchical addresses

    • multicast, anycast => QoS aware broadcasting

  • Simplified header (for realtime sevice)

  • Improved security

  • Auto-configuration

    • plug-play network access (DHCP, ND)

    • micro-mobility

  • QoS awareness

    • traffic class (8 bits)

    • flow label (20 bits, cf. VC of ATM)

Networked Video


Network layer

Version

(4)

Traffic

Class (8)

Flow Label (20)

Version

(4)

HLEN

(4)

Type of

Service (8)

Total Length (16)

Payload Length (16)

Next

Header (8)

Hop

Limit (8)

Identification (16)

Flags

(3)

Fragment

Offset (3)

TTL (8)

Protocol (8)

Header Checksum

(16)

Source Address (128)

Source IP Address (32)

Destination IP Address (32)

Destination Address (128)

Header formats of IPv4/IPv6

Networked Video


Ipv6 is reality

IPv6 is reality.

  • Worldwide IPv6 network : tunneling-based

  • IPv6 routers : 3Com, Compaq, Ericsson Telebit, Hitachi Ltd., Nokia Telecom, Northern Telecom,

  • IPv6 Linux kernel

  • Windows NT, Windows 2000

  • Future : wireless services in China, ubiquitous network

Networked Video


Multicast in ipv6

8 4 4 104 8

111111111

000T

Scope

Multicast group address

Multicast in IPv6

  • T : permanent (0) or transient (1)

  • Scope : geographic scope (within node~global)


Anycast in ipv6

Anycast in IPv6

3 5 8 32 16 64

010

Reg.

TLA

NLA

SLA

Interface ID

  • TLA, NLA, SLA : aggregators

  • Anycast : A group of hosts or routers can have the same address and provide the same service. Clients are connected to the nearest server. (cf: local broadcasting stations)

anyTV.co.kr

Networked Video


Mipv6 multimedia service

MIPv6 multimedia service

Networked Video


Intserv rsvp

IntServ/RSVP

Network Layer


Qos support in the internet

QoS Support in the Internet

  • Call admission control (CAC) traffic policing

    • by using signaling protocol

    • Traffic characteristics and requirements

  • Traffic shaping : User’s effort to keep promise

  • Traffic policing : Router’s effort to police

CAC

Traffic

shaping

Traffic

policing

Network Layer


Scheduling queuing algorithms

Scheduling (queuing) algorithms

  • FIFO (First In First Out)

  • Weighted fair queuing (WFQ)

  • Deficit round robin (DRR)

  • Stochastic fair queuing (SFQ)

  • Round robin (RR)

  • Strict priority

Network Layer


Re s ource reservation protocol rsvp

Resource reserVation Protocol (RSVP)

  • Previously, RFC1819 Internet Stream Protocol v2 (ST2+) referred as “IPv5”

  • RFC 2205 RSVP (1997)

    • RSVP and intServ : RFC 2210

  • Signaling to reserve resource along the path of particular data streams or flows

    • Unicast and multicast

    • Multipoint to multipoint

    • Multipoint to single point

Host

RESV

Router

RESV

Router

RESV

Router

RESV

Host

PATH

PATH

PATH

PATH

Network Layer


Path and resv messages

“PATH” and “RESV” Messages

  • “PATH” : from source to target

    • Marks the routed path and collects information about the QoS viability of each router along the path

  • “RESV” : from target to source

    • It the target wants, reserves resources along the path

  • Routers can “merge” downstream reservations to the same stream.

  • State is maintained as long as “PATH” and “RESV” messages flow.

  • Receiver driven (compared to broadcasting)

    • Large group, dynamicgroup membership, heterogeneous receiver requirements

    • “dynamic”=soft state : created/modified/removed

Network Layer


Network layer

RSVP

  • What I am

    • originating application and sub-flow

    • such as print flow vs. time-critical transaction

  • Who I am

    • authenticated user ID

  • What I want

    • the type of QoS service needed

  • How much I want

    • certain applications quantify their resource requirements precisely.

  • How I can be recognized

    • the 5-tuple classification criteria by which the data traffic can be recognized

  • Which network devices resources will be impacted by the associated data traffic

Network Layer


Rsvp modules in hosts and routers

RSVP modules in hosts and routers

  • ApplicationRSVP process

    • Admission control : sufficient available resources for the request?

    • Policy control : whether the use has permission for the reservation?

Host

Router

control

control

Appli-

cation

RSVP

process

RSVP

process

Policy

control

Routing

process

Policy

control

RSVP

data

Admission

control

Admission

control

classifier

classifier

intServ

Packet

scheduler

Packet

scheduler

data

data

Network Layer


Reservation request spec s

Reservation Request Spec.s

  • Filter spec. (logical)

    • Selection of subsets of the packets of a given session

    • Sender IP address and source port

    • To set parameters in the packet classifier

  • Flow spec. (quantitative)

    • Specification a desired QoS

      • Service class

      • Tspec (traffic descriptor)

      • Rspec (desired QoS parameters)

    • To set parameters in the node’s packet scheduler

Network Layer


Rsvp parameters1

RSVP parameters

  • Tspec (PATH), Rspec (RESV)

    • r : token rate

    • b : token-bucket depth

    • p : peak rate

    • m : minimum policed size

    • M : maximum packet size

  • Double leaky bucket model [r,b], [p,M]

VBR : average rate < r < p

CBR : average rate = r = p

p

<b

r

<M

Network Layer


Tspec rspec in rfc2210

Tspec/Rspec in RFC2210

Guaranteedservice

Controlled load

Network Layer


Rsvp styles

RSVP Styles

S1

S2

sender

S1

S2

  • Fixed-filter

    • All sender are active at all time.

filter

f

f

f

f

router

N

N

2f

f

receiver

R

R

  • One sender at a time

  • Wildcard-filter

    • e.g. audio conferencing

  • Shared explicit

    • The receiver select a sender.


Scalability problem

Scalability Problem

SA

DA

SP

DP

Pr

data

  • 3 step processes for every intServ packet

    • Identification of an intServ packet by 5 tuple classifiers

      {(SA, DA), (source port #, receiver port #), protocol}

    • Searching for the service spec. for the packet

    • Traffic policing and scheduling

  • Impossible inside core network

    • Maybe possible in edge routers of mobile network

1

SA

DA

SP

DP

Pr

TSpec

intServ routing table

2

SA

DA

SP

DP

Pr

TSpec

3

SA

DA

SP

DP

Pr

TSpec

4

SA

DA

SP

DP

Pr

TSpec

5

SA

DA

SP

DP

Pr

TSpec

Admission

control

classifier

Packet

scheduler

data

Network Layer


5 tuples in ipv4 and ipv6

5-tuples in IPv4 and IPv6

  • Flow ID : 104 bits in IPv4 and 296 bits in IPv6

    • IPv4 104 = 32*2 (SA, DA) + 32(SP, DP) + 8 (protocol)

    • Scalability problem in public network ~NN

  • Class ID : 6 bits in DS field  diffServ

Network Layer


Mpls multi protocol label switching

MPLS (Multi-Protocol Label Switching)

  • Scalability problem of intServ

    • A set of 5 tuples  a temporary label

    • Virtual switch for the efficiency of routers (cf. ATM)

      • Connection oriented : VC (Virtual Circuit)

      • VC lookup table (resource, path)

  • Routing flexibility

    • Traffic engineering and provisioning

    • Constraint-based routing (QoS routing)

    • FEC (Forward Equivalence Class)

      • With RSVP

         IPv6 “Flow Label”

Networked Video


Conclusions

Conclusions

  • intServ for per-flow service  IEEE801.16, UMTS~

    • RSVP for resource reservation

      • Controlled load, guaranteed service

    • CAC  traffic shaping / policing

  • Scalability problem

    • MPLS, IPv6 flow label for simplified identification

  • Advanced approach

    • RFC4495 “RSVP Extension for Reduction of Bandwidth” (2006)

    • Draft-intserv-multiple-tspec (2010)

      • “…. to dynamically adapt to available bandwidth…”

      • Multiple reservations between two endpoints

      • Refreshes only include the Tspecs that were accepted

MediaLab , Kyunghee University


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