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REQUEST_SYNC is a public packet, handled in PacketProcessor's unauthenticated branch and passed straight to GossipSyncManager. Nothing between the radio and the response limits how often a neighbor may send one, so a single peer decided how often we decode a GCS filter, run SHA-256 over every stored packet, and transmit whatever its filter claims to be missing. A filter that claims to hold nothing is a few bytes and makes us replay up to seenCapacity() packets — 500 by default. Repeating it costs the sender nothing and saturates a link measured in kbps. Give each requester a token bucket: one request per 5s with a burst of 2, so the scheduled first sync and a periodic one both land, and a response allowance that refills to seenCapacity() over the 30s periodic interval — the most a peer can legitimately be missing in one round. An honest peer never reaches either limit, so what it receives is unchanged. The bookkeeping is keyed by a peer ID off the wire, so it is an access-ordered LinkedHashMap capped at 256 entries; otherwise the mitigation would be its own memory exhaustion vector.