# eth0：巨帧被丢弃，MTU为1500但收到来自00:1a:2b:3c:4d:5e的帧大小为9000

- **ID:** `networking/ethernet-jumbo-frame-dropped`
- **领域:** networking
- **类别:** network_error
- **验证级别:** ai_generated
- **修复率:** 88%

## 根因

配置为标准1500字节MTU的网络接口接收到了大于MTU的以太网帧（巨帧），通常来自启用了巨帧的对端，导致内核因大小不匹配而丢弃该帧。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| Linux kernel 5.15 | active | — | — |
| Linux kernel 6.6 | active | — | — |
| FreeBSD 13.2 | active | — | — |

## 解决方案

1. ```
   On the sender: ifconfig eth0 mtu 1500
   ```
2. ```
   ip link set dev eth0 mtu 9000
   ```

## 无效尝试

- **Setting the MTU on eth0 to 9000 to accept jumbo frames.** — This may cause fragmentation issues if the path has other devices with lower MTU; also, it changes the interface's behavior for all traffic, not just the problematic peer. (60% 失败率)
- **Using an access control list to block large frames from the sender.** — Does not solve the root cause; the sender still sends jumbo frames, and blocking them drops legitimate traffic. (80% 失败率)