3Com 520 - Manual (Page 48)

1-34 C H A P T E R 1: G E T T I N G S T A R T E D
IP Host on the Same IP Network
If your organization operates a TCP/IP network and
needs to extend the IP network over geographically
remote sites, it is possible to bridge the network
using the OfficeConnect Remote. It is only possible to
bridge where both sites have the same network
address and the devices are on the same subnet. In a
class C IP address, the network address is the first
three groups of numbers. For example:
192.000.000.xxx
where xxx represents the host ID of the individual
devices on the subnet. See “IP Addresses” in
Appendix A for more information about addresses.
Typically IP bridging would be used to connect a
back office or home office into a main site. Any
further network connections would be carried out
from the main site. An example of such a network is
shown in Figure 1-17 .
During configuration, you enter the ISDN number and
the IP addresses of any hosts to which you want to
connect. In the example in Figure 1-17 , the IP address
of the host 191.000.000.100 is used and only when data
destined for this device is received by the OfficeConnect
Remote, is a call made to the remote site.
Figure 1-17 IP Bridged Network
There are some issues about which you should be
aware when implementing an IP bridging solution.
■ Although calls to the remote site are only generated
when data is addressed to a specific IP host or hosts
(in our example, 191.000.000.100), any data that
cannot be identified as local is also passed over the
link while it is open. This can prevent the link from
closing after the intended data has been transferred.
■ Some devices and applications (for example
autodiscovery programs on SNMP managers) poll all
devices on a subnet at regular intervals and this
could lead to frequent ISDN calls if you have entered
Rc.bk : RC01.FRM Page 34 Thursday, July 10, 1997 9:53 AM