4. Configuration3150-A2-GB24-10 March 2001 4-15Selecting the Link Layer ProtocolTwo link layer protocols, Point-to-Point Protocol (PPP) and Serial Line InternetProtocol (SLIP), are supported for connection to an external SNMP manager,Telnet device, or network device (e.g., a router). PPP can be used for synchronousor asynchronous operation. SLIP can be used for asynchronous operation only.NOTE:The carrier-mounted CSU does not support synchronous operation on theCOM port.The standalone CSU implementation of PPP supports the following: Full negotiation of PPP’s Link Control Protocol (LCP). Active negotiation of LCP when the connection is established. Maximum Request Unit (MRU) sizes up to 1500 bytes, but the CSU willattempt to negotiate down to 500 bytes. The CSU provides a unique LCP magic number derived from the unit serialnumber and the elapsed time. Full negotiation of escape characters.The CSU implementation of PPP does not support Link Quality Reports (LQR),compression, encryption, Password Authentication Protocol (PAP) or ChallengeHandshake Authentication Protocol (CHAP).The CSU implementation of SLIP supports a fixed MRU size of 1006 bytes.Before selecting the protocol, you must first select the port to be used as thecommunications link. Refer toSelecting the Port on page 4-12. This exampleshows the COM port being used as the communications link.
