Bit-and-piece attack (a.k.a carpet bombing) is the tactics that attackers use to evade detection of the target. When the attackers craft traffic small enough to bypass detection thresholds which are largely based on the volume of traffic heading for destination IPs, the traffic, once converging, is big enough to cripple the targeted site or even an entire CSP network. Owing to the negligible size of this traffic, typical security devices deployed by ASN-level CSPs are unable to detect and mitigate the traffic before it can cause any harm. The difference between the bit-and-piece pattern and traditional network-layer volumetric attacks is that bit-and-piece exploits the large attack surfaces of ASN-level CSPs, whereas the latter just zero in on one or a few IPs that serve mission-critical services such as websites and mail servers and overwhelm the target by sending voluminous amount of junk. For its details, please refer to Q3 2018 threat report. https://www.nexusguard.com/hubfs/2019%20PTC/Nexusguard_Q3%202018%20Threat%20Report.pdf