CHAPTER 1: INTRODUCTION1-22EMM-E6 User’s Guide1.9.1 MIBsThe Management Information Bases (MIBs) are a database resident onthe EMM-E6. Objects in the information base are uniquely identified byadministratively assigned identifiers (called object identifiers or OIDs),and can be viewed, retrieved, or changed using an SNMP packetexchange over the network.1.10 REVIEW OF ADDRESSINGFor network devices to recognize one another, unique identifiers, referredto as addresses, are required. The following sections are intended forreview, and do not represent a comprehensive description of networkaddressing.This section begins by discussing the two types of addressing used inTCP/IP networks, Internet Protocol (IP) addresses and Media AccessControl (MAC) addresses. These descriptions are followed by anoverview of the process of configuring addresses in a network, includingexamples of network Classes and the creation of subnets within networks.1.10.1 MAC AddressesThe MAC address is a unique, 48-bit binary number, associated with aspecific physical connection to a network which is capable of generatingpackets. Examples of devices with MAC addresses include SNMP agentsand DNI cards. MAC addresses are divided into 6 octets, and representedin hexadecimal form such as the following:00-00-1D-00-26-FBAll MAC addresses are administered by the IEEE and are generallyassigned at the time of manufacture, and cannot be changed. The firstthree octets uniquely identify the manufacturer. Cabletron devices’ MACaddresses all start with: 00-00-1D.
