Cross-layer failure restoration techniques for a robust IPTV service

Broadcast TV distribution over an IP network requires stringent QoS constraints, such as low latency and loss. The main challenge to achieving these QoS objectives is how to design the network to respond to network failures. Streaming content in IPTV is typically delivered to the distribution points on the IP backbone using IP multicast, and in the case being considered, with protocol independent multicast source specific mode (PIM-SSM). A proven failure restoration technique at the IP layer is link-restoration using MPLS or layer-2 fast reroute (FRR). Link-based FRR creates a pseudo-wire or tunnel in parallel to the IP adjacencies (links) along the forwarding path used by the PIM tree. For each such tunnel both a primary and backup path are defined. The backup path is Layer-1-disjoint from the physical link and when the link fails, the pseudo-wire can be rapidly restored. Thus, single link failures are transparent to the interior gateway protocol (IGP). Although one may choose the back-up pathpsilas IGP link weights to avoid traffic overlap during any single link failure, multiple failures may still cause traffic overlap with FRR. We present a cross-layer restoration approach that combines both FRR-based restoration for single link failure and ldquohitlessrdquo (i.e., without loss) PIM tree reconfiguration algorithms to prevent traffic overlap when multiple failures occur.