今天新装了Redhat 5.4企业版，配置了一下PPPoe，准备就驾着本本遨游了，可是令我奇怪的是，ppp的连接不停的掉线，新开一个终端，一直在Ping，发现网络隔一分钟左右就自动掉一次，然后自动重新连接，查看message日志，发现有如下内容，不断重复：
Aug  5 23:20:53 localhost pppd[5754]: pppd 2.4.4 started by root, uid 0
Aug  5 23:20:53 localhost pppd[5754]: Using interface ppp0
Aug  5 23:20:53 localhost pppd[5754]: Connect: ppp0 <--> /dev/pts/0
Aug  5 23:20:53 localhost pppoe[5755]: PPP session is 33288
Aug  5 23:20:54 localhost pppd[5754]: appear to have received our own echo-reply!
Aug  5 23:20:54 localhost pppd[5754]: PAP authentication succeeded
Aug  5 23:20:54 localhost pppd[5754]: local  IP address 10.0.0.59
Aug  5 23:20:54 localhost pppd[5754]: remote IP address 10.0.0.1
Aug  5 23:21:14 localhost pppd[5754]: appear to have received our own echo-reply!
Aug  5 23:21:34 localhost pppd[5754]: appear to have received our own echo-reply!
Aug  5 23:21:54 localhost pppd[5754]: No response to 3 echo-requests
Aug  5 23:21:54 localhost pppd[5754]: Serial link appears to be disconnected.
Aug  5 23:21:54 localhost pppd[5754]: Connect time 1.0 minutes.
Aug  5 23:21:54 localhost pppd[5754]: Sent 6578 bytes, received 13132 bytes.
Aug  5 23:21:54 localhost pppd[5754]: Connection terminated.
Aug  5 23:21:54 localhost pppoe[5755]: read (asyncReadFromPPP): Session 33288: Input/output error
Aug  5 23:21:54 localhost pppoe[5755]: Sent PADT
Aug  5 23:21:54 localhost pppd[5754]: Exit.
Aug  5 23:21:54 localhost adsl-connect: ADSL connection lost; attempting re-connection.
Aug  5 23:21:59 localhost pppd[5846]: pppd 2.4.4 started by root, uid 0
Aug  5 23:21:59 localhost pppd[5846]: Using interface ppp0
Aug  5 23:21:59 localhost pppd[5846]: Connect: ppp0 <--> /dev/pts/0
Aug  5 23:21:59 localhost pppoe[5847]: PPP session is 33544
Aug  5 23:21:59 localhost pppd[5846]: appear to have received our own echo-reply!
Aug  5 23:21:59 localhost pppd[5846]: PAP authentication succeeded
Aug  5 23:22:00 localhost pppd[5846]: local  IP address 10.0.0.5
Aug  5 23:22:00 localhost pppd[5846]: remote IP address 10.0.0.1
Aug  5 23:22:19 localhost pppd[5846]: appear to have received our own echo-reply!
Aug  5 23:22:39 localhost pppd[5846]: appear to have received our own echo-reply!
Aug  5 23:22:59 localhost pppd[5846]: No response to 3 echo-requests
Aug  5 23:22:59 localhost pppd[5846]: Serial link appears to be disconnected.
Aug  5 23:22:59 localhost pppd[5846]: Connect time 1.0 minutes.
Aug  5 23:22:59 localhost pppd[5846]: Sent 31464 bytes, received 78172 bytes.
Aug  5 23:23:00 localhost pppd[5846]: Connection terminated.
Aug  5 23:23:00 localhost pppoe[5847]: read (asyncReadFromPPP): Session 33544: Input/output error
Aug  5 23:23:00 localhost pppoe[5847]: Sent PADT
Aug  5 23:23:00 localhost pppd[5846]: Exit.

随即在网上搜了一下，发现网上出现此问题的人也不在少数，要么修改/etc/ppp/options的内容，要么就是修改/etc/ppp/pppoe-server-options的内容，我也在这两个文件上浪费了挺多的时，测试了挺久时间，网络状况依然如故，后来一想，平常修改IP的设置之类的都在网卡上设置的，就试着在 vi /etc/sysconfig/network-scripts/ifcfg-ppp0  里面作了修改，原文件如下：

USERCTL=no
BOOTPROTO=dialup
NAME=DSLppp0
DEVICE=ppp0
TYPE=xDSL
ONBOOT=no
PIDFILE=/var/run/pppoe-adsl.pid
FIREWALL=NONE
PING=.
PPPOE_TIMEOUT=80
LCP_FAILURE=3
LCP_INTERVAL=20
CLAMPMSS=1412
CONNECT_POLL=6
CONNECT_TIMEOUT=60
DEFROUTE=yes
SYNCHRONOUS=no
ETH=eth0
PROVIDER=DSLppp0
USER=46804
PEERDNS=no
DEMAND=no
IPV6INIT=no
PERSIST=no

将此文件内的二个地方作了修改：
LCP_FAILURE= 30
LCP_INTERVAL= 30

至此，一直末出现不间断掉线的情况了，其实将上面两个语句的任意一个值，修改得大些即可解决问题。