请教关于adsl在嵌入式系统中的一些问题

Question

我用的开发板是s3c2410，系统是arm-linux，内核是"2.4.18-rmk7-hzh-yaffs.tar.bz2"。adsl modem是硬置modem，IP是192.168.1.1。
刚开始时用rp-pppoe-3.6无法获得IP，adsl modem不识别我所发送的PADI包。经过检查发现2410与PC对int等数据所占的内存字节数的规定好像并不相同，所以我发送的PADI包总是在中间多出两个字节，导致adsl modem不识别这个包。后来我将pppoe.h中的结构体
typedef struct PPPoEPacketStruct {
    struct ethhdr ethHdr;        /* Ethernet header */
#ifdef PACK_BITFIELDS_REVERSED
    unsigned int type:4;        /* PPPoE Type (must be 1) */
    unsigned int ver:4;                /* PPPoE Version (must be 1) */
#else
    unsigned int ver:4;                /* PPPoE Version (must be 1) */
    unsigned int type:4;        /* PPPoE Type (must be 1) */
#endif
    unsigned int code:8;        /* PPPoE code */
    unsigned int session:16;        /* PPPoE session */
    unsigned int length:16;        /* Payload length */
    unsigned char payload[ETH_DATA_LEN]; /* A bit of room to spare */
} PPPoEPacket;
修改了一下。其中struct ethhdr ethHdr是系统定义的以太网包头。我重新写了一个结构体来替换原来的：
typedef struct PPPoEPacketStruct {
    u_int8_t h_dest[ETH_ALEN];
    u_int8_t h_source[ETH_ALEN];
    u_int16_t h_proto;
#ifdef PACK_BITFIELDS_REVERSED
    unsigned int type:4;        /* PPPoE Type (must be 1) */
    unsigned int ver:4;                /* PPPoE Version (must be 1) */
#else
    unsigned int ver:4;                /* PPPoE Version (must be 1) */
    unsigned int type:4;        /* PPPoE Type (must be 1) */
#endif
    unsigned int code:8;        /* PPPoE code */
    unsigned int session:16;        /* PPPoE session */
    unsigned int length:16;        /* Payload length */
    unsigned char payload[ETH_DATA_LEN]; /* A bit of room to spare */
} PPPoEPacket;
这里只是重新规定了以太网包头各类数据所占的字节数，其他都没有修改，发现问题解决了！终于可以从ISP服务商那里分配到IP了。
但当我ping一些网站时，发现modem有响应，也有数据的交换，但目标板却接收不到数据包。我用一个抓包工具来抓包，发现目标板的网卡上也有adsl modem所发送过来的数据包。我怀疑这可能又是哪里没定义好，导致目标板的网卡对adsl modem所发送过来的数据包不识别。
好郁闷啊，先是adsl modem不识别数据包，现在目标板又犯同样的问题，我都不知道该怎么办了。哪位高手帮我解答一下呀！

[ 本帖最后由 txb777 于 2006-4-3 12:34 编辑 ]

Answer 1

以下是pppoe在2410下连网时的信息：

Connect: ppp0 <--> /dev/pts/0
Warning - secret file /etc/ppp/pap-secrets has world and/or group access
sent [LCP ConfReq id=0x1 <mru 1492> <magic 0xe7971296>]
rcvd [LCP ConfReq id=0x1 <mru 1492> <auth pap> <magic 0x75170000>]
sent [LCP ConfAck id=0x1 <mru 1492> <auth pap> <magic 0x75170000>]
rcvd [LCP ConfAck id=0x1 <mru 1492> <magic 0xe7971296>]
sent [LCP EchoReq id=0x0 magic=0xe7971296]
Warning - secret file /etc/ppp/pap-secrets has world and/or group access
sent [PAP AuthReq id=0x1 user="100001398172" password=<hidden>]
rcvd [LCP EchoRep id=0x0 magic=0x75170000]
rcvd [IPCP ConfReq id=0x0 <addr 61.51.120.1>]
discarding proto 0x8021 in phase 5
sent [PAP AuthReq id=0x2 user="100001398172" password=<hidden>]
rcvd [PAP AuthAck id=0x2 ""]
PAP authentication succeeded
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0>]
rcvd [IPCP ConfNak id=0x1 <addr 61.51.123.14>]
sent [IPCP ConfReq id=0x2 <addr 61.51.123.14>]
rcvd [IPCP ConfAck id=0x2 <addr 61.51.123.14>]
rcvd [IPCP ConfReq id=0x1 <addr 61.51.120.1>]
sent [IPCP ConfAck id=0x1 <addr 61.51.120.1>]
local  IP address 61.51.123.14
remote IP address 61.51.120.1
其中discarding proto 0x8021 in phase 5是什么意思呀？这对上网有什么影响吗？望指教！