I need some information with your setup.
Can you post the output of following commands:

/sbin/ifconfig
netstat -r

grep telnet /etc/inetd.conf
grep ftp /etc/inetd.conf

rpm -qf /usr/sbin/in.telnetd
rpm -qf /usr/sbin/in.ftpd

cat /etc/hosts.allow
cat /etc/hosts.deny

cat /proc/interrupts
cat /proc/ioports

ps -ef

: I install a redhat 6.2 server in LAN.
: I install oracle8.16 and apache, php4 on the server.
: Now,when i telnet or ftp this server,the connection
: was often broken.
: I can ping this server,and find network is well.
: I don't know what's wrong with it.
: Please help me.
: Thanks