Described in RFC 1584, MOSPF is intended for
use within a single routing domain, such as a network controlled by
a single organization. MOSPF is dependent on the use of OSPF as the
accompanying unicast routing protocol. In an OSPF/MOSPF network,
each router maintains an up-to-date image of the topology of the
entire network. MOSPF works by including multicast information in
OSPF link-state advertisements. An MOSPF router learns which
multicast groups are active on which LANs.
This link-state information is used to
construct multicast distribution trees. MOSPF builds a distribution
tree for each (source, group) pair and computes a tree for active
sources sending to the group. The tree state is cached, and trees
must be recomputed when a link-state change occurs or when the cache
times out.
MOSPF is best suited for environments that
have relatively few (source, group) pairs active at any given time.
This protocol will work less well in environments that have many
active sources or environments that have unstable links.
Note: Cisco routers do not support
MOSPF.