# PPPoE：LCP回显超时，未收到对端192.168.100.1的响应

- **ID:** `networking/pppoe-lcp-echo-timeout`
- **领域:** networking
- **类别:** protocol_error
- **验证级别:** ai_generated
- **修复率:** 72%

## 根因

PPPoE会话的链路控制协议（LCP）回显请求未得到远程对端的确认，通常是由于接入集中器失效、DSL调制解调器故障或PPPoE服务器静默断开会话。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| pppd 2.4.9 | active | — | — |
| pppd 2.5.1 | active | — | — |
| Linux kernel 5.10 | active | — | — |

## 解决方案

1. ```
   killall pppd && pon dsl-provider
   ```
2. ```
   reboot modem via web interface or power cycle; then restart pppd: ifdown ppp0 && ifup ppp0
   ```

## 无效尝试

- **Setting lcp-echo-interval to a larger value (e.g., 60 seconds) to reduce timeout frequency.** — This only delays the inevitable disconnection; the underlying peer unresponsiveness remains, and sessions still drop after the longer timeout. (80% 失败率)
- **Adding 'noecho' option to pppd to stop sending LCP echo requests.** — Hides the failure but leaves the session in a broken state; the PPPoE connection may appear up but cannot pass traffic. (95% 失败率)