This read-only value reports the net amount of bandwidth that has been allocated or deallocated on this port but has not yet been announced to the rest of the network via OSPF, representing a lag between local resource changes and the routing protocol's awareness of them. An admin checks this when bandwidth-based route metrics seem stale, since a large lportUnsyncBandwidth value means other nodes are still routing based on outdated capacity information for this link. For example, if an admin just added a large new PVC and lportUnsyncBandwidth shows a big pending delta, that explains why OSPF-based path selection elsewhere has not yet reacted to the new load on this trunk.