Providing robust congestion control is essential prior to Internet-wide deployment of long-lived multicast flows. This thesis therefore reviews currently proposed techniques, and identifies key issues. It then proposes a new framework that enables the network to police and enforce correct congestion behaviour. Receiver-driven layer multicast congestion control is especially vulnerable to misbehaving receivers. Countering these problems demands a new paradigm to enforce correct receiver behaviour. A framework based on Explicit Congestion Notification (ECN)-nonce is proposed, which preserves the ability to work with system/network heterogeneity in the multicast tree, mandates layered multicast receivers to feedback nonce-reports in an arrayed form. Appropriate behaviour may be enforced in the new framework by introducing selected border routers in the multicast tree, known as <i>enforcers</i>. This also avoids practical limitations requiring an upgrade to all edge routers, and allows local service providers to protect their own network. The approach uses re-active policing. This can not prevent receivers joining under congestion, but reacts by preventing forwarding of specific groups within a reasonable delay. This approach eliminates the need for secure transfer of information from the sender to the enforcing routers and avoids a need to upgrade the IGMP and PIM protocols. The method is compatible with using ECN when Active Queue Management (AQM), which has benefit when using Forward Error Correction (FEC) based reliability. This framework was analysed using simulation. The thesis also analyses some important related performance issues for congestion-controlled multicast transport protocols, considering issues such as excessive overshoot and poor congestion response in delay-diversified networks using the IETF NACK-Oriented Reliable Multicast (NORM) framework and an unnecessary congestion response with heterogeneous receivers in Asynchronous Layered Coding (ALC) framework.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:509176 |
| Date | January 2009 |
| Creators | Kulatunga, Chamil |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=33532 |
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