pex+ftp+tftp+dhcp安装疑问

yjfnpl

在dhcpd.conf文件配置如下

option space PXE;
　　option PXE.mtftp-ip　　　　　　　 code 1 = ip-address;　
　　option PXE.mtftp-cport　　　　　　code 2 = unsigned integer 16;
　　option PXE.mtftp-sport　　　　　　code 3 = unsigned integer 16;
　　option PXE.mtftp-tmout　　　　　　code 4 = unsigned integer 8;
　　option PXE.mtftp-delay　　　　　　code 5 = unsigned integer 8;
　　option PXE.discovery-control　　　code 6 = unsigned integer 8;
　　option PXE.discovery-mcast-addr　 code 7 = ip-address;
　　class "pxeclients" {
　　　　match if substring (option vendor-class-identifier, 0, 9) = "PXEClient";
　　　　option vendor-class-identifier "PXEClient";
　　　　vendor-option-space PXE;
　　　　# At least one of the vendor-specific PXE options must be set in
　　　　# order for the client boot ROMs to realize that we are a PXE-compliant
　　　　# server.　We set the MCAST IP address to 0.0.0.0 to tell the boot ROM
　　　　# that we can't provide multicast TFTP (address 0.0.0.0 means no
　　　　# address).
　　　　option PXE.mtftp-ip 0.0.0.0;
　　　　# This is the name of the file the boot ROMs should download.
　　　　filename "pxelinux.0";
　　　　# This is the name of the server they should get it from.
　　　　next-server 192.168.0.1;
　　}
　　ddns-update-style interim;
　　ignore client-updates;
　　default-lease-time 1200;
　　max-lease-time 9200;
　　option subnet-mask 255.255.255.0;
　　option broadcast-address 192.168.0.255;
　　option routers 192.168.0.254;
　　option domain-name-servers 192.168.0.1,192.168.0.2;
　　option domain-name "mydomain.org";
　　subnet 192.168.0.0 netmask 255.255.255.0 {
　　range 192.168.0.10 192.168.0.100;
　　}　
　　host q10 {
　　hardware ethernet 00:00:F0:6B:38:5B;
　　fixed-address 192.168.0.22;
　　}
对于上述配置里面的红色部分,这些参数分别都是什么意思!!