2 56K LAN MODEMFUNCTIONALITY DESCRIPTIONThis chapter provides a description of the 56K LAN Modem’s key functionality,covering the following topics.n Connection Typesn Call Routing Protocol and IP Address Translationn Understanding PPTPConnection Types This section discusses LAN side and WAN side connections.56K Technology Your 56K LAN Modem utilizes the V.90 56K ITU standard, which is backwardcompatible with all US Robotics 56K standards, and is capable of downloadspeeds of up to 56K 1 . V.90 technology takes advantage of the typical networkconfiguration found when an analog modem dials into a digitally connectedInternet Service Provider. Because it requires no analog-to-digital conversions inthe downstream path (which can cause line noise), V.90 can use nearly all of theavailable 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 56Kweb site at http://www.3com.com/56k.LAN Side Connection On the LAN side, up to four users can connect to the 56K LAN Modem’s built inEthernet hub, or up to 25 users may connect to the 56K LAN Modem via anexternal user-supplied hub, enabling users to share files and printers and to useInternet 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 serverequipment. The 56K LAN Modem complies with the V.90 ITU standard and is backwards compatiblewith all US Robotics 56K standards. Standard officially determined in February, 1998; ratification expect-ed in September, 1998.
