This read-only MacAddress object identifies the second of the two peer MAC addresses that define a conversation row in the mplp peer-pair protocol-mix history table. Pairing it with Mac1Index lets an admin uniquely identify which two hosts' exchange the counters in that row of the mplp peer-pair protocol-mix history table describe, since a matrix table has one row per host pair rather than per host. When a report shows heavy traffic on a row of the mplp peer-pair protocol-mix history table, an admin checks mplpMac2Index to see the second host in that pair, e.g. confirming a backup server was talking to a specific client rather than to the whole segment.