【正文】
it 從電信公司來的四芯的線路,通常是兩對雙絞線。每對用來在一個方向發(fā)送數(shù)據(jù),所以四芯電路允許全雙工的通信。 2wire circuit 從電信公司來的兩芯的線路,通常是一對雙絞線。 2芯電路只允許半雙公通信。 T/1 允許 。 (.) T/1 mux 將一條 T/1電路復(fù)用成 24條不同的 64kbps電路。 (.) E/1 ,可以復(fù)用成 32個 64Kbps信道。 各種點到點通信協(xié)議的不同 Protocol Error Correction Architected Type Field Other Attributes SDLC (Synchronous Data Link Control) Yes None Support multipoint links。 assumes SNA header occurs after the SDLC header LAPB (Link Access Procedure Balanced) Yes None Spec assumes single configurable protocol after LAPB. Used mainly with . Cisco uses a propriedary type field to support multiprotocol traffic. LAPD (Link Access Procedure on the D Channel) No No Not used between routers. Used on D channel from router to ISDN switch for signaling. 各種點到點通信協(xié)議的不同 Protocol Error Correction Architected Type Field Other Attributes HDLC (HighLevel Data Link Control) No No Cisco’s default on serial links. Cisco uses a proprietary type field to support mulitprotocol traffic. PPP (PointtoPoint Protocol) All