Application Layer Multicast Extensions to RELOAD draft-kolberg-sam-baseline-protocol-01

1. Application Layer Multicast Extensions to RELOADdraft-kolberg-sam-baseline-protocol-01 Mario Kolberg, University of Stirling, UK (Editor) John Buford, Avaya Labs Research, USA Thomas C. Schmidt, HAW Hamburg Matthias Waehlisch, link-lab & FU Berlin

2. Overview • Baseline document • Extension to RELOAD, uses P2PSIP RELOAD as the overlay layer • Uses AMT (Automatic IP Multicasting Tunneling) for tunneling between ALM and Native Multicast regions • Main change: updated Section 4 (Hybrid ALM tree operations) • Editorial changes throughout • Request that the RG adopt this as an RG deliverable for future RFC submission • Any comments welcome!

3. Multicast • Widely considered important for consumer communications applications • Small group video conferencing • IPTV • Native multicast deployment is rather slow • Alternatives: • Application Layer Multicast • Native Multicast with tunnelling between regions • SAM RG within IRTF investigates a third option: • Hybrid protocols which use overlay multicast with native multicast where it is available

4. Hybrid Overlay Multicast • Select between OM subtree and NM subtree opportunistically • Expect improved network efficiency, increase throughput and reduce latency • Design based on AMT tunnelling mechanism • Protocol uses structured P2P overlay to connect peers in different types of multicast regions • Assumption: All tree member nodes are part of the overlay • AMT-R(elay): features a NM multicast connection to the multicast backbone • AMT-GW: does not have multicast connection to multicast backbone – uses an AMT-R to connect to the backbone

5. Example ALM-NM Toplogy

6. Sec. 4.1 Algorithm: ALM only • groupID=create(); • Allocation of unique groupID • Out of band advertisement/publishing in DHT • joinTree(groupID) • Out of band discovery of groupID (lookup in DHT) • Send join message to peer with the nearest NodeID to the groupID (tree root) • Peers on the path to the root join tree as forwarding nodes • leaveTree(groupID) • Sends leave message to each child node and the parent node • If parent is a forwarding node and this is its last child, forward to its parent • Child node receiving a leave message from parent sends join message to tree root • multicastMsg(groupID) • SSM tree: creator of tree is source; it sends data message to tree root from where it will be forwarded down the tree • ASM: peer sending message will send it to its parent and children; each node receiving message will forward it to remaining tree edges it is connected to

7. Sec. 4.2 Algorithm: ALM with peer at AMT site • Joining peer is within an AMT region with AMT-GW (P21) and uses ALM algorithm to try to connect to tree • Following cases are possible depending on which nodes respond: • NM peer in the tree which is in the same NM region as the joining peer. The joining peer uses ALM routing or connects directly to the NM peer. • NM peer which is in another NM region which supports an AMT-R (P6 and P7) or another peer which can function as a P-AMT-R (P-AMT-R17), the joining peer can use AMT to connect to one of the NM peers. • There is no NM peer in the tree. The NM peer uses ALM routing.

8. Sec. 4.3 ALM with NM peer using AMT-R • Joining peer is within an AMT region with AMT-R (P6) and uses ALM algorithm to try to connect to tree • Following cases are possible depending on which nodes respond: • NM peer in the tree which is in the same NM region as the joining peer (P7). The joining peer uses ALM routing or connects directly to the NM peer. • NM peer in the tree which is in a different NM region as the joining peer (such as P16). The joining peer can use AMT to connect to one of the NM peers. • peer in the tree which can function as P-AMT-GW (P-AMT-GW11). The NM peer can join the tree using ALM or connecting to the P-AMT-GW via its local AMT-R. • peer in the tree which is in an AMT-GW region (P21). The NM peer can join the tree using ALM or connecting to the peer via the AMT-GW and its local AMT-R. • There is no NM peer in the tree. The NM peer uses ALM routing.

9. Sec 5. Group Management API • API between Application and Group stack • Objectives: • Common multicast API for transparent communication in underlay and overlay • Abstract naming to support different distribution technologies • Access to different multicast flavours → Details in subsequent presentation

10. Sec. 6 Protocol definition • Messages between RELOAD nodes • Checked against the latest RELOAD draft, and no changes to messages required • Supports different tree formation algorithms described earlier • Control messages are propagated using overlay routing • Message categories • ALM Usage: • Tree life-cycle (create, join, leave, re-form, heartbeat) • Hybrid ALM Usage: • Tree life-cycle • AMT gateway advertisement and discovery • Peer region and multicast properties

11. V02 Changes Being Discussed • Move section 7 up just behind section 4 and reflect the achievable operations directly in reload usages.

12. RG Action Requested • Request that the RG adopt this as an RG deliverable for future RFC submission • Comments welcome