Translations:MIPS/FAQ/41/en

Have you got the SGI machine (and server) plugged into the right network ports?
Make sure the network is cabled correctly. Also note that some machines have special needs. For instance the Challenge S cannot obtain network connectivity under Linux via its UTP port, you need to use the AUI port via a transceiver.
Are there any firewalls in use?
Make sure your firewall is not blocking DHCP/BOOTP requests (ports 67 and 68 on UDP) or TFTP (port 69 on UDP). iptables -I INPUT 1 -p udp --dport 67:69 -j ACCEPT should get things rolling.
Have you disabled packet MTU discovery and set the port range?
SGI boxes require /proc/sys/net/ipv4/ip_no_pmtu_disc = 1 and /proc/sys/net/ipv4/ip_local_port_range = "2048 32767". See the Gentoo/MIPS handbook.
Note
Only required for IP22/IP28 systems. Other SGI systems can netboot without these two tweaks.
Is the server giving out the correct details via BOOTP?
Double check your /etc/dhcp/dhcpd.conf . ISC's dhcpd won't dish out addressing information via BOOTP unless the machine has been statically defined with a fixed address.
Which TFTP server are you using?
tftp-hpa is known to work. atftp is a lot more advanced, this can cause problems. If in doubt, try installing tftp-hpa and see if the problem clears up.
Are the daemons running?
dhcpd should show up when typing ps ax . As for TFTP, it'll largely depend on whether its a standalone server, or if its running from (x)inetd . tftp-hpa runs as a process called in.tftpd . Look for that in the ps ax output and start any services not currently running.
Does the kernel exist in /tftpboot ?
Make sure you place the kernel image to be booted in this directory and that it is world-readable. ( chmod 644 /tftpboot/foo ) Also, in your /etc/dhcp/dhcpd.conf , note that the path to the kernel will be relative to the /tftpboot directory if you're using tftp-hpa .
Have you unset the netaddr and dlserver PROM variables?
Try running unsetenv netaddr and unsetenv dlserver .