## The Evolution of Solana's "Immunity System": Why a 6 Тbit/s Attack Actually Demonstrates Network Resilience

Typically, when we assess the strength of a blockchain network, we're really asking: how much chaos can it withstand without collapsing? The recent test that Solana experienced directly answers this question.

According to data released by infrastructure company Pipe, Solana recently faced a traffic attack of approximately 6 Тbit/s — a figure that falls into the common category of "threat reports" on the internet, usually only encountered by the largest websites. But the key point isn't the scale of the attack itself, rather Solana's response: the network continued to produce blocks normally, validation was uninterrupted, and user fees did not spike abnormally. No emergency restart, no chaos among validators.

This stands in stark contrast to Solana's past stories. In September 2021, a flood of bot-driven transactions (originating from an IDO event on Raydium) caused the network to go offline for over 17 hours. By April 2022, during an even more intense attack, the network received 60 million transactions per second, with some nodes experiencing traffic reaching 100 Гbit/s. That incident directly led to halted block production and forced a network-wide restart.

And this time, history did not repeat itself.

## From "Passive Hit" to "Proactive Defense"

The reason Solana was able to withstand this test lies in several foundational design innovations at the network's core.

First is the upgrade of the communication protocol. Solana adopted the QUIC protocol to replace traditional connection models. The core advantage of QUIC is that it is inherently designed for multiplexing, meaning malicious actors cannot cheaply generate garbage traffic like with older protocols. Within Solana's Transaction Processing Unit (TPU) framework, QUIC introduced multiple layers of restrictions:

- Concurrency limits based on client identifiers
- Per-connection flow limits
- Dynamic restrictions based on the sender’s stake

The most clever aspect of this design is stake-weighted QoS (Quality of Service). Simply put, if a validator holds 1% of the total stake, it has the right to send 1% of the data packets to the leader. This creates a new firewall: attackers not only need bandwidth but also actual stake holdings. Small stake holders can no longer flood the network with simple spam attacks.

Second is the localization reform of the fee market. In the past, when an application was attacked or generated大量垃圾交易, the entire network would bear the cost — all transactions queued, fees skyrocketed network-wide. Solana introduced Local Fee Markets and Priority Fees mechanisms.

Users can set a cap on the computational units for their transactions and voluntarily pay extra fees to gain priority. The key detail is that priority fees are based on the declared computational limit, not the actual units consumed. Overestimating will be "punished," encouraging users to estimate accurately. This makes abuse of computational resources costly, giving the network a lever to regulate and curb malicious behavior.

## From "Shared Collapse" to "Layered Defense"

What is the combined effect of these changes? Solana has evolved from the past model of "the whole network fails if one part fails" to a multi-layered defense system.

When attack traffic reaches the boundary, it first encounters a stake-based rate limit — without sufficient stake, it cannot generate大量数据包. Even if this layer is bypassed, the priority fee mechanism raises the cost of malicious transactions, requiring real economic expenditure. Finally, even if someone is willing to pay for flood attacks, the network has local isolation mechanisms to ensure that congestion in one application does not drag down the entire system.

From another perspective, validators become roles with "tickets." You are no longer purely attacking based on bandwidth and technical means; you must have real stake invested. This naturally filters out participants without "real money" in the system and significantly raises the attack cost threshold.

## Reality and Compromises

But it’s worth noting that no system is perfect. Regarding the 6 Тbit/s attack, there is ongoing community discussion: was it a sustained traffic wall or a brief spike? Different interpretations influence the assessment of "successful defense." Internet traffic measurement itself is complex, and without independent audits, claims that "the network remains standing" are hard to verify with 100% certainty.

Another subtlety is that this stake-based priority system naturally favors operators with large capital. Small validators or individual nodes may be at a disadvantage during congestion. The system still risks becoming a hunting ground for bots willing to pay.

However, the most important shift has already occurred: Solana has moved from "passively waiting for collapse" to "actively countering attacks." Past stories involved production halts, network restarts, and lengthy coordination. This time, the story is: the chain remains active, transactions continue confirming, and user perception is minimally affected.

This indicates that Solana has evolved from an "easily defeated network" into one that "wears out attackers first." This mindset shift may be more meaningful than any single technical upgrade.