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Motivation

Andrey Ermolinskiy (UC Berkeley)Sylvia Ratnasamy (Intel Research Berkeley )Scott Shenker (UC Berkeley)

Free Riding Multicast

IP Multicast: extension to IP unicast for one-to-many communication

Applications IP-TV multimedia conferencingmassive multi-player games

Benefits efficient multipoint communication group-based communication abstraction

Problem: complexity of existing solutions

multitude of routing protocols (Cisco routers implement 8 multicast protocols!) hard for ISPs to configure and manage

Today: little inter-domain ISP deployment despite router and OS vendor

supportFRM: a new approach to inter-domain multicast that reduces protocol complexity

exploits technology trends that endow routers with more memory and computation

(1) Group Membership Discovery A domain augments its BGP advertisements with an encoding of the multicast groups active within its domain

(2) Multicast Forwarding Originating domain computes the AS-level tree from the union of the BGP unicast paths to each member domain Encodes the tree in packet header and forwards packet to its children on tree Each child in turn forwards along the tree edges encoded in the packet

protocol: simple extension to BGP no multicast routing protocol ISP control via existing BGP framework general service model; efficient source-rooted trees

evaluated via trace-driven simulationimplemented in Linux, XORP router no change to endhosts; compatible with legacy BGP

AS P

AS XAS Y

AS Z

AS Q AS U

AS V

AS M

a.b.*.*: {Gr, Gb}c.d.e.*: {Gr, Gb}

p.q.*.*: {Gr}

AS P

AS XAS Y

AS ZAS Q

AS U

V

AS M

a.b.*.*: {Gr, Gb}c.d.e.*: {Gr, Gb}f.g.*.* : {Gb}m.n.*.*: {Gr, Gb}

V

Q U

P Z

X Y

Advantages Status

FRM Approach