Cabletron Systems CSX1200, CSX1000 manual PPP Background Information

CONFIGURING OTHER ADVANCED OPTIONS

PPP Configuration

LINK FAILURE DETECTION STATUS

You can enable or disable the link failure detection feature. If enabled, there will be a periodic transmission of Echo-Request frames, a maintenance type frame provided by PPP’s Link Control Protocol. Reception of the appropriate Echo-Reply frame indicates a properly functioning connection; incorrect replies or lack of replies indicate a connection failure.

ECHO FREQUENCY

This specifies, in seconds, how often the Echo-Request frames are transmitted (see above element). The default value is 10 seconds.

MAXIMUM ATTEMPTS

This specifies how many consecutive Echo-Requests are sent without receiving a reply before declaring the PPP link to be faulty. The default value is 3 attempts.

PPPBACKGROUND INFORMATION

Point-to-Point Protocol (PPP) can provide standard interoperability for remote devices. Interoperability will allow remote devices made by different manufacturers to operate and exchange 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-link connection.

3.A family of Network Control Protocols (NCPs) for establishing and configuring different network-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 link

After a link is established through LCP, the Network Control Protocols (NCPs) manage the specific needs required by each device’s network-layer protocol.

PPPLINK FAILURE DETECTION

On a point-to-point link, there are a variety of failures which can occur on the intervening communications path and/or within the remotely connected system. Often times, such failures are detectable via a signalling mechanism associated with the link. For example, a failure of an ISDN B-channel usually leads to a corresponding failure of the associated D-channel, an event which is suitable 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.

Workgroup Remote Access Switch 335