Cabletron Systems CyberSWITCH CSX150 User Manual

Also see for CyberSWITCH CSX150: User guide Quick start guide

Contents

Small Office Remote Access Switch 317C ONFIGURING O THER ADVANCED O PTIONSPPP ConfigurationLINK FAILURE D ETECTION S TATUSYou can enable or disable the link failure detection feature. If enabled, there will be a periodictransmission of Echo-Request frames, a maintenance type frame provided by PPP’s Link ControlProtocol. Reception of the appropriate Echo-Reply frame indicates a properly functioningconnection; incorrect replies or lack of replies indicate a connection failure.ECHO FREQUENCYThis specifies, in seconds, how often the Echo-Request frames are transmitted (see above element).The default value is 10 seconds.MAXIMUM ATTEMPTSThis specifies how many consecutive Echo-Requests are sent without receiving a reply beforedeclaring the PPP link to be faulty. The default value is 3 attempts.PPP BACKGROUND I NFORMATIONPoint-to-Point Protocol (PPP) can provide standard interoperability for remote devices.Interoperability will allow remote devices made by different manufacturers to operate andexchange information on the same network.PPP consists of three main parts:1. A method of encapsulating datagrams so that they can be more easily transmitted over point-to-point links.2. A Link Control Protocol (LCP) for establishing, configuring, and testing the data-linkconnection.3. A family of Network Control Protocols (NCPs) for establishing and configuring differentnetwork-layer protocols.Link Control Protocol (LCP) is used to:• automatically agree upon the encapsulation formation options• handle the varying limits on sizes of packets• authenticate the identity of the remote device on the link• determine when a link is functioning properly• detect common misconfiguration errors• terminate the linkAfter a link is established through LCP, the Network Control Protocols (NCPs) manage the specificneeds required by each device’s network-layer protocol.PPP L INK FAILURE D ETECTIONOn a point-to-point link, there are a variety of failures which can occur on the interveningcommunications path and/or within the remotely connected system. Often times, such failures aredetectable via a signalling mechanism associated with the link. For example, a failure of an ISDNB-channel usually leads to a corresponding failure of the associated D-channel, an event which issuitable for concluding that the B-channel has failed. Similarly, the Local Management Interface(LMI) facility of a Frame Relay circuit may provide feedback suitable for determining that an end-to-end Virtual Circuit has failed.