Information About OSPFv2-OSPF Live-Live
Overview of OSPFv2-OSPF Live-Live
Many new applications driving the growth of networking market are multicast based. Applications such as Internet Protocol television (IPTV) are typically associated with simultaneously delivering massive amount of sensitive data streams to large audiences. Packet drop is a critical issue in multimedia traffic. There is a demand to reduce multicast traffic loss to the range of milliseconds or to zero packet loss. The zero packet loss solution for multicast in case of single link failure is also known as live-live.
In a live-live network, multicast streams (typically two flows) form their own reverse path forwarding (RPF)/shortest path trees (SPT) over diversified physical links, so that failure on one link does not affect multicast traffic on other link. The existing multi topology technology in Cisco IOS software supports the multiple multicast topologies.
The OSPFv2-OSPF Live-Live feature enables the protocol independent multicast (PIM) to handle multiple multicast topologies. When a multicast topology is created and enabled on OSPF, IP prefixes on each topology are injected into topology-based Routing Information Base (RIB). PIM then decides which RIB to use for RPF lookup.
PIM RPF topology is a collection of routes used by PIM to perform the RPF operation when building shared or source trees. In a multi topology environment, multiple RPF topologies can be created in the same network. A particular source may be reachable in only one of the topologies or in several of them through different paths.
- Configure a policy that maps a group range to a topology. When RPF information needs to be resolved for the RP or the sources for a group within the range, the RPF lookup takes place in the specified topology. This can be used for PIM Sparse Mode (PIM-SM)/source-specific multicast (SSM)/Bidirectional(Bidir) PIM.
- Configure a policy that maps a source prefix range to a topology. This can be used for PIM-SM and PIM-SSM.
- Use the topology identified by the Join Attribute encoding in the received PIM packets.
The PIM Join Attribute extends PIM signaling to identify a topology that should be used when constructing a particular multicast distribution tree. For more details on the PIM Join Attribute, see PIM Multi-Topology ID (MT-ID) Join-Attribute IEEE draft.