IP MULTICAST Adiseshu Hai, T. V. Lakshman and Godon Wilfong Nokia DIMACS Wokshop on Algoithms fo Data Cente Netwoks Rutges Univesity, NJ 1
Why is IP Multicast not deployed in public netwoks? Denial-of-Sevice (DoS) attack amplification Complex Contol Plane Lage Fowading state - Non aggegable Multicast state flow Multicast data flow Multicast contol plane Multicast data plane 2
Can SDN help with Multicast? Denial-of-Sevice (DoS) attack amplification Contol state Fowading state Multicast state flow Multicast data flow Multicast SDN Contolle Multicast SDN switch 3
Can we eliminate multicast fowading state in SDN? Eliminate unicast fowading state in SDN: - Path Switching: pe-flow outing without pe-flow state - New data path suitable fo SW switches and pogammable packet pocessos - Encode path in the packet heades - DIMACS 2016 4
Eliminating unicast fowading state in SDN using Path Switching SDN Contolle 5
Can we eliminate multicast fowading state in SDN? Can we extend Path Switching to encode multicast paths? Can we ceate an efficient encoding of a multicast path? No blowup in packet size (e.g. using bitmaps) No blowup in stoage state (e.g,. encode each multicast tee by a unique identifie) 6
Can we educe multicast fowading state in SDN? Unicast Banching (UB) - Use banching nodes in the netwok to eplicate unicast flows. - Use SDN Flow Table at ingess and egess - Use SDN Goup Table at banching nodes Reduces multicast fowading state fom linea to sublinea in numbe of fowading nodes 7
Unicast Banching (UB) Refeence Diagam Cental Contolle Banching Nodes With Goup Tables 8 Tansit Switches Fist Hop Switches Fist Hop Switches Endpoints Endpoints
Reducing multicast fowading state in SDN using Unicast Banching (UB) UB state flow UB data flow UB SDN Contolle Unicast switch Ingess, Egess, Banching SDN switch 9
Added advantages of Unicast Banching (UB) Tunable knob to switch between unicast eplication and full multicast Allows fo an NFV based implementation Allows Taffic Engineeed banches - Fast Reoute, Pe banch QoS Woks at all potocol layes potocol agnostic - Ethenet, IP, MPLS Enables unicast only potocols like Segment Routing and TCP to be multicast capable* - HTTP Adaptive Steaming multicast - Efficient content caches Enables Policy Based Multicast 10 * Requies stateful NFV elements, not just SDN switches fo banching points
Policy Based Multicast Policy based netwoking: Rules fo non default outing - Geofencing - QoS - Membeship filteing UB enables Policy Based Multicast - Numbe, location and type of banching nodes 11
Whee ae the Algoithms? 12
Building Efficient Policy Based Multicast Tees Poblem 1 definition: - Given an ingess node, a set of egess nodes and a set of banching nodes, build an optimal multicast tee. - What is optimal - Usual definition is based on link cost. - Steine tee poblem (NP-complete) 13
Building Multicast Tees using UB Majo Issue UB based multicast tee is not a tee!!! - It is a configuation Cannot apply Steine tee appoximation solutions diectly. Poblem: How to ceate minimum cost configuations? b 2 G 1 14
Tansfomation to Steine tee poblem on H Define : Edge-weighted gaph H = (O,E). O is set of banching nodes (including teminals) e=(b,b ) O, w(e) = length shotest path containing no intenal O nodes b G 2 1 2 H b 5 5 2 1 4 15 Theoem: Minimum cost configuation poblem in G is equivalent to Steine tee poblem in H
Minimum cost configuation poblem Theoem: Thee is a polynomial-time 1.39-appoximation algoithm fo min cost configuation poblem. [BGRS10] Theoem: The minimum cost configuation poblem is APX-had. Poof: Follows fom APX-hadness of Steine poblem fo complete gaphs with weights 1 and 2. [BP89] 16
Poblem 2: Minimize banching nodes Poblem 1: Minimize cost given a set of banching nodes. MIN COST PROBLEM Poblem 2: Minimize numbe of banching nodes given a fixed cost. MIN BRANCHING PROBLEM 17
Min Banching Poblem Fo a subset X of the tansit nodes, let CX be the minimum cost valid configuation using X as the set of exta banching nodes. We ae given a gaph G = (V, E), a multicast demand d = (, 1, 2,..., t), a bound k and an attainable cost c. Does thee exists a banching set X with least cost valid configuation CX satisfying d whee X <= k and cost(cx) <= c. 18 Does anybody
Min Banching Poblem Theoem: This poblem is NP-complete. Poof: Follows fom a constuction using Set Cove. Coollay: Fo this poblem the best possible appoximation is ln n. Poof: Follows fom bounds fo Set Cove. 19 Does anybody
20 Theoem: Min Banching is NP-complete 1 a b c e f n 1 C m C n e b a m f e c C C,,,,, 1, 1 n demand,,, 1
Policy Diven Softwae Defined Multicast Using Efficient Selection of Unicast Banching Points Conclusion: - Unicast Banching based multicast povides fo efficient, policy diven Softwae Defined Multicast. 21