I have 2 unix boxes setup in a similar manner what I did was
configured my Linksys to maintain a range of addresses for dhcp
probably the same as you but I configured the Sun Ulltra 2's
running Solaris 8 with static Ip's and stayed away from using DHCP because it made life easy for the suns to be up and not rely
on the LynkSys router for there IP's.

If you really want to use DHCP though you may need to recycle
the LynkSys I find it gets hung up especially when using a network hub chained to it.

Other than that make sure you have all proper file settings to use
dhcp on your sun boxes.

you can also use snoop -a dhcp to check for response from your
DHCP server.

The above will give you audible clicks for any dhcp network traffic
this is helpful in troubleshooting any Dynamic Host Configration Protocol.

Anything else Go to http://docs.sun.com/ab2/coll.834.2/D...ocView/idmatch(DHCP-CONFIG-67)?Ab2Lang=C&Ab2Enc=iso-8859-1

and read up on DHCP config to make sure your not missing something.
Configuring and Unconfiguring a Solaris DHCP Client
When you install the Solaris operating environment from CD-ROM, you are prompted to use DHCP to configure network interfaces. If you select yes, the DHCP client software is enabled on your system during Solaris installation. You do not need to do anything else on the Solaris client to use DHCP.

If a client system is already running the Solaris operating environment and not using DHCP, you must unconfigure the system and issue some commands to set up the system to use DHCP when it boots.

If your client is not a Solaris client, consult the client documentation for configuration instructions.

How to Configure a Solaris DHCP Client
This procedure is necessary only if DHCP was not enabled during Solaris installation.

Become superuser on the client system.

If this system uses preconfiguration instead of interactive configuration, edit the sysidcfg file to add the dhcp subkey to the network_interface keyword.

For example, network_interface=le0 {dhcp}. See the sysidcfg(4) man page for more information.

Unconfigure and shut down the system by typing the following command:


# sys-unconfig


See the sys-unconfig(1M) man page for more information about what configuration information is removed by this command.

Reboot the system after it has completely shut down.

You are prompted for system configuration information by sysidtool programs when the system reboots. See the sysidtool(1M) man page for more information.

When prompted to use DHCP to configure network interfaces, specify Yes.

If you preconfigured the system by using a sysidcfg file, insert the network_interface keyword, and specify dhcp as a dependent keyword. For example, network_interface=le0 {dhcp}.

How to Unconfigure a Solaris DHCP Client
Become superuser on the client system.

If you use a sysidcfg file to preconfigure the client, remove the dhcp subkey from the network_interface keyword.

Unconfigure and shut down the system by typing the following command:


# sys-unconfig


See the sys-unconfig(1M) man page for more information about which configuration information is removed by this command.

Reboot the system after it has completely shut down.

Because you unconfigured the system, you will be prompted for configuration information by sysidtool programs when the system reboots. See the sysidtool(1M) man page for more information.

When prompted to use DHCP to configure network interfaces, specify No.

If you use sysidcfg to specify configuration, you will not be prompted.