Building a Robust, Ubiquitous Multicast Infrastructure Linda Winkler Argonne National Laboratory

Objectives n Support for native multicast routing n Scalable, inter-domain policy-based routing n Allow for variety of intra-domain protocols and topologies

Multicast Forwarding n Uses the source address to make forwarding decision n Reverse path forwarding (RPF)- router forwards a multicast datagram only if received on the upstream interface to the source

Multicast Distribution Trees n Defines the network path along which traffic will flow from source to receiver n Built based on multicast routing protocol employed

Protocol Independent Multicast-Dense Mode n Independent of unicast routing protocol used n Reverse path forward flood and prune- data driven n Useful when senders and receivers in close proximity; few senders and many receivers; volume of traffic is high; bandwidth is plentiful

Protocol Independent Multicast-Spare Mode n Independent of unicast routing protocol used n Receiver initiated membership n Receivers join hop by hop toward rendezvous points (RP) n Senders register with the RP n Data flows down the shared tree only toward places that need the data n Useful when few receivers; senders and receivers geographically dispersed

Multicast Source Discovery Protocol (MSDP) n Allows RPs to share group memberships n Intra-domain exchange of group state and active sources n Allows each AS to choose its own mode, sparse or dense

Multicast Border Gateway Protocol (MBGP) n Makes use of the multiprotocol extensions to BGP4+ n Routers carries two sets of routes- one for unicast and one for multicast n Multicast routes are used to build data distribution trees n Allows non-congruent unicast and multicast topologies n Where unicast and multicast topologies are congruent, allows differing policies

High Performance Backbone Networks & Multicast Configuration n Abilene, APAN/TransPAC, ESnet, NREN, vBNS n Route exchange –MBGP provides scalable, policy based EGP n Tree building/multicast forwarding protocol –PIM allows for (M)BGP inter-domain and IGP intra-domain n PIM-DM initially (floods state to collocated RPs) n PIM-SM (reduces flood-prune, requires MSDP) n PIM-Spare-Dense (depends if RP is known) n Method for identifying active sources –dense mode floods data to establish state –MSDP floods Source Active packets to MSDP intra-domain peers

STARTAP NGIX-C Multicast vBNS TANet SingAREN NREN Abilene CANARIE TransPAC

NGIX-C Issues n Multipoint vs Point-to-Point interface n Monitoring –mSD by Peter Parnes in Sweden –AU, JP, KR, STARTAP soon n Debugging