Windows XP在接收到DHCP Offer之后，没有发送DHCP Request消息

实验环境：

DHCP Server：

  系统Ubuntu 10.04  , DHCP Server : dnsmasq

DHCP Relay：

  系统Ubuntu 10.04， DHCP Relay为WiMAX网关。

 

现象：

  (1)  Win XP收到DHCP Offer，没有响应。

  (2)  Ubuntu下客户端能够正常获得IP地址。

 

在多次尝试后，并查看外国网站上的文章。最后了解到。Linux下,和XP上的DHCP实现是有些不同的。

 

Frame 13 (342 bytes on wire, 342 bytes captured)

Ethernet II, Src: Intel_c1:3a:11 (00:04:23:c1:3a:11), Dst: Broadcast (ff:ff:ff:ff:ff:ff)
Internet Protocol, Src: 192.168.130.1 (192.168.130.1), Dst: 255.255.255.255 (255.255.255.255)
User Datagram Protocol, Src Port: 10426 (10426), Dst Port: bootpc (68)
Bootstrap Protocol
    Message type: Boot Reply (2)
    Hardware type: Ethernet
    Hardware address length: 6
    Hops: 0
    Transaction ID: 0x6fabf38e
    Seconds elapsed: 0
    Bootp flags: 0x0000 (Unicast)
    Client IP address: 0.0.0.0 (0.0.0.0)
    Your (client) IP address: 192.168.130.100 (192.168.130.100)
    Next server IP address: 192.168.66.52 (192.168.66.52)
    Relay agent IP address: 192.168.130.253 (192.168.130.253)
    Client MAC address: Dell_58:b6:36 (00:15:c5:58:b6:36)
    Server host name not given
    Boot file name not given
    Magic cookie: (OK)
    Option: (t=53,l=1) DHCP Message Type = DHCP Offer
    Option: (t=1,l=4) Subnet Mask = 255.255.255.0
    Option: (t=58,l=4) Renewal Time Value = 4 days
    Option: (t=59,l=4) Rebinding Time Value = 7 days
    Option: (t=51,l=4) IP Address Lease Time = 8 days
    Option: (t=54,l=4) Server Identifier = 192.168.66.52
    Option: (t=15,l=7) Domain Name = "abc.com"
    Option: (t=3,l=4) Router = 192.168.130.1
    Option: (t=6,l=8) Domain Name Server
    End Option
    Padding

如上的消息，在Win XP中，客户端接收到消息后，将不会做任何反应。

因为Win XP判断比较严格，必须按照RFC2131标准的消息格式，客户端才会接收DHCP消息。

如上消息的三个红色的地方必须是一致的。

即：

Dst: Broadcast (ff:ff:ff:ff:ff:ff)

Dst: 255.255.255.255 (255.255.255.255)

Bootp flags: 0x8000 (Broadcast)

或

Dst: Broadcast (11:22:33:44:55:)

Dst: 192.168.1.172 (192.168.1.172)

Bootp flags: 0x0000 (Unicast)

这两种中的一种，才会被Win XP所接收.