The system FDB table size is configurable as follows:
configure
service
system
fdb-table-size table-size
where table-size can have values in the range from 255999 to 2047999 (2000k).
The default, minimum, and maximum values for the table size are dependent on the chassis type. To support more than 500k MAC addresses, the CPMs provisioned in the system must have at least 16 GB memory. The maximum system FDB table size also limits the maximum FDB table size of any card within the system.
The actual achievable maximum number of MAC addresses depends on the MAC address scale supported by the active cards and whether selective learning is enabled.
If an attempt is made to configure the system FDB table size such that:
the new size is greater than or equal to the current number of allocated FDB entries, the command succeeds and the new system FDB table size is used
the new size is less than the number of allocated FDB entries, the command fails with an error message. In this case, the user is expected to reduce the current FDB usage (for example, by deleting statically configured MAC addresses, shutting down EVPN, clearing learned MACs, and so on) to lower the number of allocated MAC addresses in the FDB so that it does not exceed the system FDB table size being configured.
The logic when attempting a rollback is similar; however, when rolling back to a configuration where the system FDB table size is smaller than the current system FDB table size, the system flushes all learned MAC addresses (by performing a shutdown then no shutdown in all VPLS services) to allow the rollback to continue.
The system FDB table size can be larger than some of the line card FDB sizes, resulting in the possibility that the current number of allocated global MAC addresses is larger than the maximum FDB size supported on some line cards. When a new line card is provisioned, the system checks whether the line card's FDB can accommodate all of the currently allocated global MAC addresses. If it can, then the provisioning succeeds; if it cannot, then the provisioning fails and an error is reported. If the provisioning fails, the number of global MACs allocated must be reduced in the system to a number that the new line card can accommodate, then the card-type must be reprovisioned.