3Com 3C840 manual Add ip network houston address 192.75.202.99/23

IP Addressing Basics B-5

with OfficeConnect Remote 840. The first option permits you to set the subnet via numerical (8-30 bits) designation. For example:

add ip network houston address 192.75.202.99/23

Secondly, you can specify a class designation: A, B, or C. You can also leave the subnet value blank and let the OfficeConnect Remote 840 choose it for you. In this case, however, OfficeConnect Remote 840 will specify a class setting based on the IP address. For example:

add ip network houston address 192.75.202.99/C

To avoid confusion when configuring an IP address and subnet mask for a user, as opposed to a network, be aware that some user commands (e.g.: set network user) offer the option of H for the subnet class designator.

This value can be used only when the station being identified is a host. Networked nodes still require class or numeric (8-32 bits) subnets. For example:

set vc same remote_ip_address 234.170.168.0/h

IP Subnet Mask Subnet masking is used to expand the number of networks due to the Address 32-bit limitation of an IP's address field. When assigned an address by the

NIC, the address can be further broken down to expand the single net number to many more by using host bits.

IP Planning If you are not very familiar with IP addressing, read the following sections to gain a better understanding before assigning addresses.

Assigning IP In IP, every “interface” typically gets an address. Interface, in this context, Addresses and tends to mean “IP port.” Your workstations each have one IP port--its

Subnetting Ethernet adapter card, which is connected to an Ethernet hub by a twisted-pair cable. The OfficeConnect Remote 840, however, has multiple ports: one ethernet and one for each virtual circuit over the ATM WAN interface. An OfficeConnect Remote 840's LAN (Ethernet) port must be assigned an address, but assigning the WAN ports an address is optional. Not providing a WAN IP address creates and unnumbered WAN interface. This feature simplifies configuration but is not always available because it must be used at both ends of the connection. For more information on unnumbered interfaces see the last section in this appendix, “IP Numbered and Unnumbered Links”.