每过 2 小时，所有工作站都会断网 10 秒。ISP 技术支持似乎不愿意解决这个问题，所以我想自己解决这个问题。这是我们的网络图：
我编写了一个 shell 脚本来记录掉线情况。该脚本（在远程服务器上）每秒 ping 我们的外部 IP 地址，并记录 ping 失败的时间。以下是日志的摘录：
=======================================
Failure Start Length
=======================================
2016-08-16 17:52:11 10 sec
2016-08-16 19:52:23 10 sec
2016-08-16 21:52:34 10 sec
2016-08-17 23:52:46 10 sec
另外，以下是路由器日志的摘录：
50 2016-08-16 17:29:03 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
51 2016-08-16 17:31:07 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
52 2016-08-16 17:33:11 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
53 2016-08-16 17:35:15 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
54 2016-08-16 17:36:51 <5> : WAN1:DHCP lease timeout, beging a new one.
55 2016-08-16 17:38:51 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
56 2016-08-16 17:40:55 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
57 2016-08-16 17:42:59 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
58 2016-08-16 17:45:03 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
59 2016-08-16 17:47:07 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
60 2016-08-16 17:49:11 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
61 2016-08-16 17:51:15 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
62 2016-08-16 17:51:51 <5> : WAN1:DHCP renew fail, begin a new discovery.
63 2016-08-16 17:52:02 <5> : WAN1:DHCP getting IP succeeded, and IP addr:XX.XX.XX.97, mask:255.255.254.0, gateway:XX.XX.XX.1.
64 2016-08-16 18:54:06 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
65 2016-08-16 18:56:10 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
66 2016-08-16 18:58:14 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
67 2016-08-16 19:00:18 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
68 2016-08-16 19:02:22 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
69 2016-08-16 19:04:26 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
70 2016-08-16 19:06:30 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
71 2016-08-16 19:08:34 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
72 2016-08-16 19:10:38 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
73 2016-08-16 19:12:42 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
74 2016-08-16 19:14:46 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
75 2016-08-16 19:16:50 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
76 2016-08-16 19:18:54 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
77 2016-08-16 19:20:58 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
78 2016-08-16 19:23:02 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
79 2016-08-16 19:25:06 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
80 2016-08-16 19:27:10 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
81 2016-08-16 19:29:14 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
82 2016-08-16 19:31:18 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
83 2016-08-16 19:33:22 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
84 2016-08-16 19:35:26 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
85 2016-08-16 19:37:02 <5> : WAN1:DHCP lease timeout, beging a new one.
86 2016-08-16 19:39:02 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
87 2016-08-16 19:41:07 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
88 2016-08-16 19:43:10 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
89 2016-08-16 19:45:14 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
90 2016-08-16 19:47:19 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
91 2016-08-16 19:49:22 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
92 2016-08-16 19:51:26 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
93 2016-08-16 19:52:02 <5> : WAN1:DHCP renew fail, begin a new discovery.
94 2016-08-16 19:52:14 <5> : WAN1:DHCP getting IP succeeded, and IP addr:XX.XX.XX.97, mask:255.255.254.0, gateway:XX.XX.XX.1.
95 2016-08-16 20:54:18 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
96 2016-08-16 20:56:22 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
97 2016-08-16 20:58:26 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
98 2016-08-16 21:00:30 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
99 2016-08-16 21:02:33 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
100 2016-08-16 21:04:37 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
101 2016-08-16 21:06:41 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
102 2016-08-16 21:08:46 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
103 2016-08-16 21:10:50 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
104 2016-08-16 21:12:54 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
105 2016-08-16 21:14:58 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
106 2016-08-16 21:17:02 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
107 2016-08-16 21:19:06 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
108 2016-08-16 21:21:09 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
109 2016-08-16 21:23:14 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
110 2016-08-16 21:25:17 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
111 2016-08-16 21:27:22 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
112 2016-08-16 21:29:26 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
113 2016-08-16 21:31:30 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
114 2016-08-16 21:33:34 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
115 2016-08-16 21:35:38 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
116 2016-08-16 21:37:14 <5> : WAN1:DHCP lease timeout, beging a new one.
117 2016-08-16 21:39:14 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
118 2016-08-16 21:41:18 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
119 2016-08-16 21:43:22 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
120 2016-08-16 21:45:26 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
121 2016-08-16 21:47:30 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
122 2016-08-16 21:49:34 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
123 2016-08-16 21:51:38 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
124 2016-08-16 21:52:14 <5> : WAN1:DHCP renew fail, begin a new discovery.
125 2016-08-16 21:52:25 <5> : WAN1:DHCP getting IP succeeded, and IP addr:XX.XX.XX.97, mask:255.255.254.0, gateway:XX.XX.XX.1.
126 2016-08-16 22:54:29 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
127 2016-08-16 22:56:33 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
128 2016-08-16 22:58:37 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
129 2016-08-16 23:00:41 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
130 2016-08-16 23:02:45 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
131 2016-08-16 23:04:49 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
132 2016-08-16 23:06:54 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
133 2016-08-16 23:08:58 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
134 2016-08-16 23:11:02 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
135 2016-08-16 23:13:05 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
136 2016-08-16 23:15:09 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
137 2016-08-16 23:17:13 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
138 2016-08-16 23:19:17 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
139 2016-08-16 23:21:21 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
140 2016-08-16 23:23:26 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
141 2016-08-16 23:25:30 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
142 2016-08-16 23:27:34 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
143 2016-08-16 23:29:38 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
144 2016-08-16 23:31:42 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
145 2016-08-16 23:33:46 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
146 2016-08-16 23:35:50 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
147 2016-08-16 23:37:25 <5> : WAN1:DHCP lease timeout, beging a new one.
148 2016-08-16 23:39:25 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
149 2016-08-16 23:41:29 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
150 2016-08-16 23:43:33 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
151 2016-08-16 23:45:37 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
152 2016-08-16 23:47:41 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
153 2016-08-16 23:49:45 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
154 2016-08-16 23:51:49 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
155 2016-08-16 23:52:25 <5> : WAN1:DHCP renew fail, begin a new discovery.
156 2016-08-16 23:52:37 <5> : WAN1:DHCP getting IP succeeded, and IP addr:XX.XX.XX.97, mask:255.255.254.0, gateway:XX.XX.XX.1.
157 2016-08-17 00:54:42 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
158 2016-08-17 00:56:46 <5> : WAN1:DHCP send DHCP-REQUEST timeout.
每次我们遇到掉线情况，路由器都会记录“DHCP 更新失败”和“DHCP 获取 IP 成功”。这可能是什么问题？这与外部 IP 地址的租约时间有关吗？
这些“DHCP 发送 DHCP-REQUEST 超时”日志又是什么呢？
谢谢！
答案1
看来您的 ISP 网络管理员在 DHCP 上的配置有问题。DHCP 客户端的标准设置是在租约过半时调用续订，并不断尝试直到续订完成。日志告诉我您的 ISP 有 2 小时的租约。但续订到一半时失败了。可能被阻止了。
我还看到 DHCP 发现正在运行，但 DHCP 更新没有运行。
继续跟踪他们。我怀疑他们有网络管理员的空缺，而其他人正在试图填补这个职位。或者他们有一位缺乏经验的新人。阅读 DHCP RFC，然后打电话给他们的支持技术人员。