3com 3C886 Manual De Usuario

This chapter provides a description of the 56K LAN Modem’s key functionality, 
covering the following topics.

■

Connection Types

■

Call Routing Protocol and IP Address Translation

■

Understanding PPTP

This section discusses LAN side and WAN side connections.

Your 56K LAN Modem utilizes the V.90 56K ITU standard, which is backward 
compatible with all US Robotics 56K standards, and is capable of download 
speeds of up to 56K

1

. V.90 technology takes advantage of the typical network 

configuration found when an analog modem dials into a digitally connected 
Internet Service Provider. Because it requires no analog-to-digital conversions in 
the downstream path (which can cause line noise), V.90 can use nearly all of the 
available 64K network bandwidth. (Upstream data, typically less speed sensitive, 
travels at the standard V.34 rate.) 

Further information is available in Appendix A of this User Guide, or visit the 56K 
web site at 

On the LAN side, up to four users can connect to the 56K LAN Modem’s built in 
Ethernet hub, or up to 25 users may connect to the 56K LAN Modem via an 
external user-supplied hub, enabling users to share files and printers and to use 
Internet email. An example of ten workstation connections is shown in Figure 3. 

1.Capable of receiving at up to 56 Kbps and sending at up to 33.6 Kbps. Due to FCC regulations, re-
ceiving speeds limited to 53 Kbps. Actual speeds may vary. Requires compatible phone line and server
equipment. The 56K LAN Modem complies with the V.90 ITU standard and is backwards compatible
with all US Robotics 56K standards. Standard officially determined in February, 1998; ratification expect-
ed in September, 1998.