Avaya P580 - Manual (Page 418)

10-14 Avaya P550R, P580, P880, and P882 Multiservice Switch User Guide,v5.3.1
Chapter
NBMA IP Interfaces
Overview
Non-broadcast multi-access (NBMA) functionality was added to RIP
and OSPF routing protocols on the Avaya Multiservice switch
software. Support for this functionality was added to enable route
exchange over nonbridged connections (routed PVCs).For more
information about NBMA, refer to the "NBMA IP Interfaces" in
Chapter 11, “
Configuring the OSPF Routing Protocol ”.
CAUTION
The 5.3.1 NBMA feature is not backward compatible. If you have
NBMA interfaces set up and need to downgrade from v5.3.1 to a 5.2
version of software, contact technical support.