# Packet Discard Rules

For all supported types of traffic (TCP, UDP, ICMP, and GRE), NAT discards packets in the following cases:

- When the translation table is full (that is, no more entries can be added).
- When the address pool is exhausted for outbound packets with inside source dynamic translation.
- When no match can be found for the destination addresses of inbound packets.
- When the address pool is exhausted for inbound packets with outside source dynamic translation.

In addition, NAT discards GRE packets under the following conditions:

- When the GRE packets match an NAPT rule.
- When Firewall is functioning.