There are a couple of issues and i am not sure if i manage to answer them all right now (RL demanding my attention), so stay tuned for more tomorrow:

1. Your network setup

Please refrain from posting photos, they are using an awful lot of bandwidth. I have redrawn your picture using ASCII graphics using vi:

Code:

  Switch                 WLAN-Router
    ---                    ---
     |  +--------------+    |
     |--| ProLiant 1   |----|
     |  +--------------+    |
     |  +--------------+    |
     |--| ProLiant 2   |----|            +--------------+
     |  +--------------+    |------------| Laptop       |
     |  +--------------+    |            +--------------+
     |--| ProLiant 3   |----|
     |  +--------------+    |
     |  +--------------+   ---
     |--| Rasberry 1   |    
     |  +--------------+    
     |  +--------------+    
     |--| Rasberry 2   |    
     |  +--------------+    
     |  +--------------+
     |--| Rasberry 3   |
     |  +--------------+
    ---

You have two separate ethernets: one which connects all the servers and one which connects all the ProLiants with the Laptop. While this is possible, it is not desirable at all for your cause.

Such a setup, with a separate "admin LAN" to access the systems is sometimes used in very big installations (data centers) to make it easier to create firewall-rules to limit the physical connection to the admin LAN. You use that to restrict access only to a select number designated client systems, so that even knowing the password would not help a prospective hacker as long as he hasn't access to such a system (the admins workplace) too.

A serious drawback of this setup is that access to the Rasberry systems is only possible via one of the ProLiants, so you will have to enable IP-forwarding on at least one of them or connect the Rasberries to the WLAN router.

In short: this is not a good idea and i think you could make life easier for you. Consider the following:

Code:

                                Switch
                                  ---
                  WLAN-Router      |
                     ---           |  +--------------+
                      |            |--| ProLiant 1   |
                      |------------|  +--------------+
   +--------------+   |            |  +--------------+
   | Laptop       |---|            |--| ProLiant 2   |
   +--------------+   |            |  +--------------+
                     ---           |  +--------------+
                                   |--| ProLiant 3   |
                                   |  +--------------+
                                   |  +--------------+
                                   |--| Rasberry 1   |
                                   |  +--------------+
                                   |  +--------------+
                                   |--| Rasberry 2   |
                                   |  +--------------+
                                   |  +--------------+
                                   |--| Rasberry 3   |
                                   |  +--------------+
                                  ---

This way you need access only to the WLAN-Router to access your whole network and you do not need to activate IP-forwarding (which creates problems all of its own).

You may notice that i haven't made any distinction between WLAN and cable-bound Ethernet: the reason is that there is no difference. For networking a WLAN connection is just "another sort of cable", so to say and above the level of cabling it doesn't matter.

Notice also, that eth1 on the ProLiants is not used any more. You do not need it.

2. DHCP

DHCP (Dynamic Host Configuration Protocol) is a way to assign IP hosts with addresses and was invented to deal with a scarcity of IP addresses. Normally, every IP host will have an address. If you have more and more hosts sharing the same network range IP addresses will eventually become scarce. DHCP was invented, so that this problem could be somewhat alleviated. Not all the systems are permanently active, therefore you do not need as many addresses as you have hosts, but only so many as you have active hosts. One system would do the bookkeeping and give out "leases" with IP addresses when a host starts and collect these addresses when the host shuts down. A host would not be guaranteed to get the same address again if it reconnects.

It is possible to run a network with servers using DHCP if you use some sort of dynamic DNS, so that the IP addresses are dynamic while the DNS names of the servers are static. This is sometimes done (again: in big data centers with hundreds(thousands of servers), but would add a lot of configuration effort to your setup. AND you do not need it at all.

My suggestion is to give static IP addresses to all the servers. Then construct a common /etc/hosts and distribute this among the systems to have name resolution. This is not as elegant as setting up a DNS server, but it is done in seconds instead of hours and the drawbacks for six servers and one client (the laptop) are zero.

You can activate DHCP for your laptop or not, it doesn't matter. If you want to access the Internet at the same time from the laptop you will have to configure it this way:

- use an outside DNS server (to resolve names in the internet)
- put the file "/etc/hosts" with your local systems on it.
- let take "/etc/hosts" take precedence by setting "local, bind4" in "/etc/netsvc.conf"

Now, if you use a name, first the file "/etc/hosts" is queried for it, only then the DNS is asked. Because the DNS would not know about your servers this is as it should be.

a possible "/etc/hosts" could look like:

Code:

# Suppose the internal network to be 192.168.128/8
# Layout:  1-50 Infrastructure
#          51-99 Servers
#          100-  Clients

# ------------------------------------------------------------- Infrastructure
192.168.128.1      router router.mynetwork.org
# 192.168.128.2      printer1 printer1.mynetwork.org      # activate if you have a printer

# ------------------------------------------------------------- Servers
192.168.128.51      proliant1 proliant1.mynetwork.org
192.168.128.52      proliant2 proliant1.mynetwork.org
192.168.128.53      proliant3 proliant1.mynetwork.org
192.168.128.54      rasberry1 rasberry1.mynetwork.org
192.168.128.55      rasberry2 rasberry2.mynetwork.org
192.168.128.56      rasberry3 rasberry3.mynetwork.org

# ------------------------------------------------------------- Clients
# This only if you want to use static IPs for the laptop too
# 192.168.128.100     mylaptop mylaptop.mynetwork.org

So far, stay tuned for more. If you have questions, feel free to ask.

I hope this helps.

bakunin