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DMS-100 Family EIU User Guide TELECOM12
185
Appendix I: Obtaining a MAC address
This appendix provides information on media access control (MAC)
addresses
1
, and on obtaining a MAC address for the Ethernet interface unit
(EIU).
Overview
The standard among manufacturers of Internetworking hardware is that the
MAC address is hard-coded in read-only memory (ROM) on each device. The
address becomes a unique identifier, and this standard ensures that no two
devices have the same identifier.
The EIU departs from this standard in that, while Nortel controls the MAC
address and the address is still unique, the operating company is responsible
for recording this address in datafill. While there is flexibility in assigning the
MAC address to EIU, this flexibility can cause problems if MAC addresses are
not unique across the network or the Internetwork. The operating company
must ensure that the datafilled address is correct, or addressing conflicts can
occur.
Administrative personnel assign a unique MAC address to each EIU using
table control datafill in table LIUINV.
MAC address format
As defined by IEEE Standard 802.3, a MAC address is either 16 or 48 bits
long. SuperNode supports 48-bit addresses. The 48-bit MAC address structure
is shown in figure 47.
1. The MAC address is also known as an Ethernet address. In this document, the industry -
standard term MAC address is used.