Cabletron Systems CyberSWITCH CSX150 User Manual

Also see for CyberSWITCH CSX150: User guide Quick start guide

Contents

Small Office Remote Access Switch 185CONFIGURING A LTERNATE ACCESSESX.25 AccessesX.25 R ELIABILITY , W INDOWS , AND A CKNOWLEDGMENTX.25 SEQUENCE N UMBER RANGEThe type of sequence numbers to be used for X.25; regular or extended. Extended sequencenumbering allows for packets to be assigned sequence numbers from 0-127 (modulo 128),as opposed to 0-7 (modulo 8). The default value is modulo 8.M AXIMUM W INDOW S IZEThis is the largest possible window size to be supported on any virtual circuit. The windowsize is the number of frames that a DTE can send without receiving an acknowledgment.SVCs that support window size negotiation will never allow the agreed upon window sizeto exceed this value. Using modulo 128, the DTEs can send up to 127 frames withoutreceiving an acknowledgment. Using modulo 8, the DTEs can send up to 7 frames withoutreceiving an acknowledgment. The default value for both modulo 8 and modulo 128 is 2.M AXIMUM P ACKET S IZEThis value is used to determine the maximum packet size that the system will support forX.25 connections. When packet size negotiation is performed on SVCs, this value will beused as the upper bound. The default maximum packet size is 128 bytes.X.25 Q UALITY - OF -SERVICE F ACILITIESThe X.25 Quality-of-Service Facilities apply only to SVCs. The first three configuration elements arefor SVCs that support negotiation.M AXIMUM THROUGHPUT C LASSThis value is used to determine the maximum throughput class that the system willsupport for X.25 connections. Throughput describes the maximum amount of data that canbe sent through the network, when the network is operating at saturation. Factorsinfluencing throughput are line speeds, window sizes, and the number of active sessionsin the network. When throughput class negotiation is performed on SVCs, this value willbe used as the upper bound. The default value is 19,200 BPS.F LOW C ONTROL N EGOTIATIONThis configuration element specifies whether Flow Control Negotiation is to be supportedfor SVCs (negotiation is not performed on PVCs). If Flow control negotiation is supportedfor SVCs, the window and packet sizes can be negotiated between DTEs on a per-call basis.As a default, this facility is not supported.THROUGHPUT C LASS NEGOTIATIONThis configuration element specifies whether Throughput Class Negotiation is to besupported for SVCs (negotiation is not performed on PVCs). This facility allows thethroughput rates to be negotiated between DTEs on a per-call basis. As a default, thisfacility is not supported.Note: The next 6 items configured for the X.25 Quality of Service Facilities are the non-standard default parameters for SVCs that do not support negotiation. These pa-rameters are used on SVCs that do not use the standard X.25 values, but also donot support any facility negotiation.