Cabletron Systems CSX1200 User Manual

Also see for CyberSWITCH CSX1000: User guide Quick start

Contents

Workgroup Remote Access Switch 207CONFIGURING A LTERNATE ACCESSESX.25 AccessesN ONSTANDARD D EFAULT R ECEIVE W INDOW S IZEThe number of frames that a DTE can receive without receiving an acknowledgment. Usingmodulo 128, the DTEs can send up to 127 frames without receiving an acknowledgment. Usingmodulo 8, the DTEs can send up to 7 frames without receiving an acknowledgment. The defaultvalue for both modulo 8 and modulo 128 is 2.N ONSTANDARD D EFAULT T RANSMIT P ACKET S IZEThe size of a packet that a DTE can transmit. The choice of a packet size must be weighed againstthe requirements for larger buffers at all the machines that process the packet. Larger packet sizesreduce the opportunity for other devices to share the channel. On the other hand, a larger packetreduces the ratio of overhead fields to user data. The default transmit packet size is 128 bytes.N ONSTANDARD D EFAULT R ECEIVE P ACKET S IZEThe size of a packet that a DTE can receive. The choice of a packet size must be weighed against therequirements for larger buffers at all the machines that process the packet. Larger packet sizesreduce the opportunity for other devices to share the channel. On the other hand, a larger packetreduces the ratio of overhead fields to user data. The default transmit packet size is 128 bytes.N ONSTANDARD D EFAULT T RANSMIT THROUGHPUT C LASSTransmit throughput describes the maximum amount of data that can be sent through the network,when the network is operating at saturation. Factors influencing throughput are line speeds,window sizes, and the number of active sessions in the network. The default value is 19,200 BPS.N ONSTANDARD D EFAULT R ECEIVE T HROUGHPUT CLASSReceive throughput describes the maximum amount of data that can be received through thenetwork, when the network is operating at saturation. Factors influencing throughput are linespeeds, window sizes, and the number of active sessions in the network. The default value is 19,200BPS.X.25 A CCESS B ACKGROUND I NFORMATIONX.25 was developed to provide an interface that would allow computers or terminals that usedifferent data communications protocols to exchange data across wide area packet-switchingnetworks. Since its inception by CCITT in 1974, it has been expanded to include many options,services, and facilities.Packet-switching is a transmission method in which data is broken down into packets. The packetsare sent across a shared medium from source to destination. The transmission may use anyavailable circuit. The next packet in the transmission may take a different route. Multiple packetsfrom the same transmission can be sent at the same time. Because of the switching, the packets maynot all take the same route, and they may not arrive in the order that they were sent. When theyarrive at their destination, the packets are reassembled in the proper order, and a check is done tosee if all expected packets arrived.X.25 provides common procedures between a device (DTE) and a packet network (DCE) forestablishing a connection to the network, exchanging data with another DTE, and releasing theconnection. X.25 contains no algorithms for routing the packets across the wide area network.Consequently, an X.25 Network does not mean that the internal operations of the network use X.25.It simply means that the interface to a packet data network is governed by the X.25 protocol.Virtual circuits are used to establish a virtual path from one DTE to another. This virtual pathappears to have the same characteristics that you might get from a physical telephone circuit. With