我是 DHCP 领域的新手。我有一个带有 DHCP 客户端的设备，有时无法获取 IP 地址。当我开始通过 Wireshark 分析 DHCP 帧时，我得到了以下两种类型的帧。
帧 A 是 DHCPREQUEST 收到服务器 ACK 的情况，帧 B 则没有收到任何响应。
[框架—A]
No. Time Source Destination Protocol Length Info
2093 319.751000000 0.0.0.0 255.255.255.255 DHCP 342 DHCP Request - Transaction ID 0x3239d4b2
Frame 2093: 342 bytes on wire (2736 bits), 342 bytes captured (2736 bits) Ethernet II, Src: Industri_00:b6:04 (00:0b:d8:00:b6:04), Dst: Broadcast (ff:ff:ff:ff:ff:ff) Internet Protocol Version 4, Src: 0.0.0.0 (0.0.0.0), Dst: 255.255.255.255 (255.255.255.255) User Datagram Protocol, Src Port: bootpc (68), Dst Port: bootps (67) Bootstrap Protocol
Message type: Boot Request (1)
Hardware type: Ethernet (0x01)
Hardware address length: 6
Hops: 0
Transaction ID: 0x3239d4b2
Seconds elapsed: 0
Bootp flags: 0x0000 (Unicast)
Client IP address: 0.0.0.0 (0.0.0.0)
Your (client) IP address: 0.0.0.0 (0.0.0.0)
Next server IP address: 0.0.0.0 (0.0.0.0)
Relay agent IP address: 0.0.0.0 (0.0.0.0)
Client MAC address: Industri_00:b6:04 (00:0b:d8:00:b6:04)
Client hardware address padding: 00000000000000000000
Server host name not given
Boot file name not given
Magic cookie: DHCP
Option: (53) DHCP Message Type
Length: 1
DHCP: Request (3)
Option: (50) Requested IP Address
Length: 4
Requested IP Address: 172.16.220.155 (172.16.220.155)
Option: (61) Client identifier
Length: 7
Hardware type: Ethernet (0x01)
Client MAC address: Industri_00:b6:04 (00:0b:d8:00:b6:04)
Option: (55) Parameter Request List
Length: 7
Parameter Request List Item: (1) Subnet Mask
Parameter Request List Item: (3) Router
Parameter Request List Item: (6) Domain Name Server
Parameter Request List Item: (15) Domain Name
Parameter Request List Item: (44) NetBIOS over TCP/IP Name Server
Parameter Request List Item: (46) NetBIOS over TCP/IP Node Type
Parameter Request List Item: (47) NetBIOS over TCP/IP Scope
Option: (255) End
Option End: 255
Padding
[框架—B]
No. Time Source Destination Protocol Length Info
135 20.969000000 0.0.0.0 255.255.255.255 DHCP 342 DHCP Request - Transaction ID 0xcc160e02
Frame 135: 342 bytes on wire (2736 bits), 342 bytes captured (2736 bits) Ethernet II, Src: Industri_00:b6:04 (00:0b:d8:00:b6:04), Dst: Broadcast (ff:ff:ff:ff:ff:ff)
Destination: Broadcast (ff:ff:ff:ff:ff:ff)
Source: Industri_00:b6:04 (00:0b:d8:00:b6:04)
Type: IP (0x0800)
Internet Protocol Version 4, Src: 0.0.0.0 (0.0.0.0), Dst: 255.255.255.255 (255.255.255.255) User Datagram Protocol, Src Port: bootpc (68), Dst Port: bootps (67) Bootstrap Protocol
Message type: Boot Request (1)
Hardware type: Ethernet (0x01)
Hardware address length: 6
Hops: 0
Transaction ID: 0xcc160e02
Seconds elapsed: 0
Bootp flags: 0x0000 (Unicast)
Client IP address: 172.16.220.155 (172.16.220.155)
Your (client) IP address: 0.0.0.0 (0.0.0.0)
Next server IP address: 0.0.0.0 (0.0.0.0)
Relay agent IP address: 0.0.0.0 (0.0.0.0)
Client MAC address: Industri_00:b6:04 (00:0b:d8:00:b6:04)
Client hardware address padding: 00000000000000000000
Server host name not given
Boot file name not given
Magic cookie: DHCP
Option: (53) DHCP Message Type
Length: 1
DHCP: Request (3)
Option: (61) Client identifier
Length: 7
Hardware type: Ethernet (0x01)
Client MAC address: Industri_00:b6:04 (00:0b:d8:00:b6:04)
Option: (55) Parameter Request List
Length: 7
Parameter Request List Item: (1) Subnet Mask
Parameter Request List Item: (3) Router
Parameter Request List Item: (6) Domain Name Server
Parameter Request List Item: (15) Domain Name
Parameter Request List Item: (44) NetBIOS over TCP/IP Name Server
Parameter Request List Item: (46) NetBIOS over TCP/IP Node Type
Parameter Request List Item: (47) NetBIOS over TCP/IP Scope
Option: (255) End
Option End: 255
Padding
我正在尝试拔下并插入网线。这是 DHCP 客户端的问题还是服务器配置不正确的问题。
谁能分享一些提示？
答案1
你的直觉是正确的。
我在这里看不到任何可以区分这两个数据包的东西（尽管在 wireshark 界面之外读取有点困难）。事务 ID 和一些其他应该会有所不同的字段是不同的，但仅此而已。
所以你的客户端没问题。那么中间设备和/或服务器呢？
如果服务器是实际服务器或其他可以捕获流量的设备，那么这就是您的下一步。从那一端查看故障情况。