Multicast and Broadcast for the Future Internetfif.kr/fiwc2008/docs/3-3.pdf · to introduce...

Multicast and Broadcast for the Future Internet

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the Future Internet

Hojin Lee (lumiere@mmlab.snu.ac.kr)

2008.02.20

Contents• Multicast Research

– Native IP Multicast– Application Layer Multicast

• Main Driving Forces

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• Main Driving Forces• Indirection• Conclusion

Multicast Research

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Native IP Multicast• Based on IP Network• Many intra-domain, inter-domain multicast routing protocols– Intra-domain: DVMRP, MOSPF, CBR, PIM-DM, PIM-SM, …

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SM, …– Inter-domain: QoSMIC, PIM-SM/MSDP, BGMP, EXPRESS, …

• Support large multicast group• However, large number of multicast groups?

Application Layer Multicast• To address deployability problem of native IP multicast– POM (Proxied Overlay Multicast)– ESM (End System Multicast)

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– ESM (End System Multicast)

• Efficiency?

Classification

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Illustration

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(a): Native IP multicast (b): ESM (c): POM

Activities of Multicast Research (1/2)

• IETF WG– multicast group management

• magma WG (http://www.ietf.org/html.charters/magma-charter.html)

– multicast routing protocols

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– multicast routing protocols• mboned WG (http://www.ietf.org/html.charters/mboned-

charter.html)• pim WG (http://www.ietf.org/html.charters/pim-charter.html)• idr WG (http://www.ietf.org/html.charters/idr-charter.html)

– missing features in current multicast• rmt WG (http://www.ietf.org/html.charters/rmt-charter.html)• msec WG (http://www.ietf.org/html.charters/msec-charter.html)

Activities of Multicast Research (2/2)

• IETF RG– Scalable Adaptive Multicast RG (http://www.samrg.org)

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to introduce broadcast and multicast

Main Driving Forces10

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to introduce broadcast and multicast schemes…

L. Henden, et al., “Broadcast and multicast – a vision on their role in future broadband access networks,” Broacast Multicast Cluster, IST, Jan 2005

1. Saving Bandwidth• Effective utilization

of bandwidth– Bandwidth and server requirement will increase fast.

11

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increase fast.

– Current solution: increase the capacity of both the backbone and the server at the same speed. � A cost-intensive concealment of the real problem

2. Economy12

• The costs of multicast services are related to:– Network deployment– Installation of CPE– Management– Maintenance

• For multicast,

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• For multicast,– The initial costs are higher– The cost of adding new users decreases proportional with

increasing number of receivers.• The use of multicast only make sense when the bandwidth savings are larger than the deployment and management cost.

3. Introduction of E-based Services

• Participation in the modern e-society– Digital divide

• It represents a threat to the development of an information society serving everybody.

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• Community type services– E-government, E-health, E-learning– A huge amount of information should be

delivered to many receivers, which will take advantage of multicast

(4. Changes of Traffic Type)• Data -> Streaming

• Live streaming service– Real time sport broadcasting

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– Real time sport broadcasting– News– …

• IPTV, …

Indirection

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Unicast vs. Multicast• IP unicast

– direction: a destination address• IP multicast

– indirection: a group address instead of individual

R1

R2

RG

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– indirection: a group address instead of individual destination addresses

* Indirection: the ability to reference something using a name, reference,

or container instead of the value itself [ wikipedia]

R3

R4

R5

G

Basic• Indirection architecture

– Each packet is associated with an id – Receiver: inserts trigger (id, addr) into the network– Sender: sends packet (id, data)

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– support general communication abstractions• unicast, multicast, anycast, host mobility

General Communication Abstractions

• multicast

• mobility

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• anycast

Multicast• Receivers insert triggers with same identifier• Can dynamically switch between multicast and unicast

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Sender Receiver (R1)

Receiver (R2)

trigger

id R2

trigger

id R1

Mobility• Host just needs to update its trigger as it moves from one subnet to another

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Sender

Receiver

(R1)

Receiver

(R2)

id R1id R2

Anycast• Use longest prefix matching instead of exact matching– Prefix p: anycast group identifier– Suffix si: encode application semantics, e.g., location

send(R1,data)

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Sender

Receiver (R1)

p|s1 R1send(p|a,data)

Receiver (R2)p|s2 R2

p|s3 R3

Receiver (R3)

Underlay vs. Overlay• Underlay routing (network infra entity)

– simple for scalability, efficiency, cost and robustness• unicast

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• unicast– general communication abstractions are supported by overlay• can be applied into a new network with minor or no modification

Example• ID space [0..63] partitioned across five i3 nodes • Each host knows one i3 node• R inserts trigger (37, R); S sends packet (37, data)

3S

send(37, data)

02m-1

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7

20

35

41

37 R

3

7

20

35

41

37 R

R

trigger(37,R)

send(R, data)

Chord circle

R

Multicast• Logical links between indirection servers– bound out-degree

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• Tree optimization

Indirection Multicast Architecture• Hierarchy

– physical topology consideration• Scalability

– member aggregation

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– member aggregation– flow aggregation

• User indirection multicast

Hierarchy• Assign ID to servers

– randomly• flat label

– with additional information

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– with additional information• hierarchy

– more hierarchy, less anonymity• why?

– aggregation

Aa0 Aa1

Ab0

Ac0Ac1

Ba0

Ba1

source

aggregation

Infra Indirection Multicast

Big Picture

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Aa1

Aa2

Ac2

Ba2Bb1

Bb0

User Indirection Multicast

Ba0 Ba1

HierarchyBa0Ab0

source

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Aa0 Aa1

Aa2

HierarchyBa0 Ba1

Ab0

source

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Aa0 Aa1

Aa2

Hierarchy - Issues• How to make hierarchical ID for indirection servers– ?: ASN# + IP prefix + random value

• Which ID is assigned to a new

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• Which ID is assigned to a new indirection server– ?: two neighbor indirection servers’ ID / 2

• Reassignment indirection server ID– ?

Scalability• IP unicast

– LPM -> aggregation• IP multicast

– multicast group addresss has no meaning (flat label)

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– multicast group addresss has no meaning (flat label) -> no-aggregation => state per flow

– cf> volatile– scalable in terms of the number of multicast members

– not scalable in terms of the number of multicast groups

Scalability – flow aggregation• ID assignment

– Flexible ID assignment and re-assignment for a flow

– An ID assignment for a group of flowsabc.001

abc.xxx

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– An ID assignment for a group of flows

• ID summarization– ID & group_prefix = a set of flows

abc.001

abc.002

abc.003

abc.999

User Indirection Multicast• Dense multicast group in the same subnet or nearby subnet– Temporarily end host performs indirection– end host

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– end host• less powerful, limited uplink bandwidth• less stable• my resource

Conclusion• Using Indirection

– general communication abstractions– anonymity

• Focus on multicast

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• Focus on multicast– physical topology consideration– scalability– user indirection

References• i3• wikipedia• secure indirection• chord

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• chord

Appendix• Splitting L3 into

– communication service layer

– forwarding layer communication service layer

- multicast

APP/ transport

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– forwarding layer - multicast

- anycast

- mobility

MAC/ PHY

forwarding layer

(basic: unicast)

Aa0Aa1

Aa2

Bb0

Bb1

Bb2

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Ac2

Ba0

Ba1

Ab0

Ac1

Ac0