GE MiCOM P40 Agile Technical Manual

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4 GENERAL FUNCTIONS FOR REDUNDANT ETHERNET BOARDSThe following functions apply to all redundant Ethernet protocols.4.1 FORWARDINGThe MiCOM Ethernet switch products support store and forward mode. The switch forwards messages with knownaddresses to the appropriate port. The messages with unknown addresses, the broadcast messages and themulticast messages are forwarded out to all ports except the source port. MiCOM switches do not forward errorpackets, 802.3x pause frames, or local packets. 802.1p priority tagging is enabled on all ports.4.2 SIMPLE NETWORK MANAGEMENT PROTOCOL (SNMP)Simple Network Management Protocol (SNMP) is a network protocol designed to manage devices in an IP network.SNMP uses a Management Information Base (MIB) that contains information about parameters to supervise. TheMIB format is a tree structure, with each node in the tree identified by a numerical Object Identifier (OID). Each OIDidentifies a variable that can be read or set using SNMP with the appropriate software. The information in the MIBis standardized.Each system in a network (workstation, server, router, bridge, etc.) maintains a MIB that reflects the status of themanaged resources on that system, such as the version of the software running on the device, the IP addressassigned to a port or interface, the amount of free hard drive space, or the number of open files. The MIB does notcontain static data, but is instead an object-oriented, dynamic database that provides a logical collection ofmanaged object definitions. The MIB defines the data type of each managed object and describes the object.The SNMP-related branches of the MIB tree are located in the internet branch, which contains two main types ofbranches:● Public branches (mgmt=2), which are defined by the Internet Engineering Task Force (IETF).● Private branches (private=4), which are assigned by the Internet Assigned Numbers Authority (IANA). Theseare defined by the companies and organizations to which these branches are assigned.The following figure shows the structure of the SNMP MIB tree. There are no limits on the width and depth of theMIB tree.Chapter 5 - OperationPx4x-REB-TM-EN-6 69