System information

5500 Express IP Control Unit
281
• Original network uses subnet mask 255.255.255.0 and is assigned
addresses 100.100.100.0 through 100.100.100.255 (See Figure 155)
• Desire to split this address space so that 64 addresses are reserved for
use by the twinax workstations attached to the IBM 5500 control unit and
192 addresses are left for other LAN devices.
• Twinax workstation use subnet mask 255.255.255.192 and can take any
contiguous 64 addresses between 100.100.100.0 and 100.100.100.255.
We is highly recommended that the twinax workstations use the upper end
of the available range of addresses, in this case 100.100.100.192 through
100.100.100.255. It is also critically important that none of the addresses
in the range reserved for the twinax workstations be assigned to any
device anywhere else on the network.
• Because three of these addresses are consumed by the TCP/IP network
architecture (you should not use the first, second or last address in the
range), there are 61 addresses left for use by twinax workstations
attached to the IBM 5500 control unit.(100.100.100.194 through
100.100.100.254).
• No upstream router table changes are required because the IBM 5500
control unit and the total address space is already properly routed to the
existing LAN.
Figure 156. Example of a Network before Installing the IBM 5500
• No subnet mask changes are required on devices attached to the LAN
(any other time you subnet a network all of the subnet masks must be
changed to reflect the network number for each subnet). You must assign
LAN
Subnet mask: 255.255.255.0
Address range: 100.100.100.0
through 100.100.100.255