Which of the following is a true statement?

In a dynamic network, a higher MAC address age-time causes learned entries to remain in the Forwarding Database (FDB) for a longer period. This slow removal of potentially stale entries, combined with the constant learning of new MACs, increases the total number of entries held in the FDB at any given time. To prevent the FDB from reaching its capacity—which would cause flooding for unlearned destinations—a larger fdb-table-size is required to accommodate the accumulation of both active and inactive entries. A lower age-time would have the opposite effect, clearing stale entries faster and thus reducing the required table size.

A. A lower age-time purges entries faster, which reduces the required FDB size, not increases it.
C. A higher age-time coupled with a smaller FDB size would increase the risk of table exhaustion and flooding.
D. The age-time is a critical parameter for managing FDB occupancy; a direct relationship exists between them.

1. Nokia 7450 ESS, 7750 SR, 7950 XRS, and VSR Layer 2 Services and EVPN Guide, Release 21.10.R1, Document ID: DC211000611. In the "VPLS" chapter, section "FDB Management", the guide states: "When the FDB is full, no new MAC addresses can be learned, which causes flooding of all traffic for unknown destinations." The subsequent section on "MAC Aging" explains that a shorter aging time helps prevent the FDB from becoming full in dynamic environments, which logically implies that a longer (higher) aging time contributes to the FDB filling up, thus necessitating a larger table size.

2. Kurose, J. F., & Ross, K. W. (2017). Computer Networking: A Top-Down Approach (7th ed.). Pearson. In Chapter 6, "The Link Layer and LANs," the section on "Link-Layer Switches" (specifically 6.3.2) describes the switch table (FDB). It explains that entries are removed after a period of inactivity (the aging time) to prevent the table from filling up with obsolete entries. This principle directly supports the conclusion that a longer aging time requires a larger table to avoid overflow in a dynamic environment.