莫名其妙的收到PADT，求高人解救

做的软件，里面有PPPOE多拨功能，根据用户反馈总是掉线(单拨也掉)，但是我在学校这边测没有问题，很奇怪
测试条件有限我无法重现这个故障，但是根据用户反馈来的log信息看，该用户的接入服务器总是在200秒后突然强制中断连接（PADT）。。
我实现协议的时候，C/S有数据交流的时候重置定时器（10秒），定时器到时间就发送echo request来保持连接。
这都是参考的mikrotik pppoe那个代码来的
 
有没有做过pppoe客户端的同志，帮忙分析下。。。。为什么服务器要PADT。。。
 
[ 0][11837.934383]Interface: \DEVICE\{D443C8F7-B642-4A72-96F4-45BCDE3BEE82}  StartDial,Sending PADI..
[ 0][11837.936684]ReceiveDiscovery from 08:19:A6:26:EB:AE  bind:00:00:00:00:00:00
[ 0][11837.936694]Receive PADO
[ 0][11837.936700]  Get ACName
[ 0][11837.936704]Send PADR.
[ 0][11837.938852]ReceiveDiscovery from 08:19:A6:26:EB:AE  bind:00:00:00:00:00:00
[ 0][11837.938862]Receive PADS.SessionID = B520
[ 0][11837.938867]Send LCP Config Request..
[ 0][11837.938956]Receive LCP Config request.
[ 0][11837.938962] Server request PAP.
[ 0][11837.938970]Send LCP Ack.
[ 0][11837.941340]Receive LCP Config ack.
[ 0][11837.941346]LCP Config Stage end.
[ 0][11837.941349]Send PAP Request..
[ 0][11837.962780] PAP Response ACK.
[ 0][11837.962789]Send IPCP Request.
[ 0][11837.962810]Receive IPCP request
[ 0][11837.962851]Send IPCP Ack.
[ 0][11837.966073]Receive IPCP nak.
[ 0][11837.966082]Send IPCP Request.
[ 0][11837.967746]Receive IPCP ack
[ 0][11837.967753]Get LocalIp 6482167C
[ 0][11837.967759]Get PriDns F28357D2
[ 0][11837.967763]Get SecDns FB8357D2
[ 0][11857.810833] Receive Ehco Request. Send Reply..
[ 0][11877.825258] Receive Ehco Request. Send Reply..
[ 0][11897.841787] Receive Ehco Request. Send Reply..
[ 0][11917.806585] Receive Ehco Request. Send Reply..
[ 0][11933.148448]Timer   State:PPP_IP.
[ 0][11933.148460] Send Lcp Echo Request.
[ 0][11933.150383] Receive Ehco reply.
[ 0][11937.816447] Receive Ehco Request. Send Reply..
[ 0][11957.857655] Receive Ehco Request. Send Reply..
[ 0][11977.818161] Receive Ehco Request. Send Reply..
[ 0][11997.834547] Receive Ehco Request. Send Reply..
[ 0][12017.879906] Receive Ehco Request. Send Reply..
[ 0][12027.883978]Timer   State:PPP_IP.
[ 0][12027.883989] Send Lcp Echo Request.
[ 0][12027.885342] Receive Ehco reply.
[ 0][12037.829197] Receive Ehco Request. Send Reply..
[ 0][12037.841514]ReceiveDiscovery from 08:19:A6:26:EB:AE  bind:00:00:00:00:00:00
[ 0][12037.841527]Receive PADT
 
 
 
 

做了个抓包的功能，写pcap文件
 
然后用wireshark看了下用户反馈的pcap没有发现特别的其他协议信息。。
 
后来意识到很可能是MagicNum的问题
 
我在回复服务器的echo request的时候没有修改magicnum
 
可能导致某些支持环路检测的BAS定期PADT...