ZyXEL P-304 User Guide - Page 68

PPTP Protocol Overview, Diagram 4 PPTP Protocol Overview, Control and PPP Connections

Get ZyXEL P-304 PDF manuals and user guides View all ZyXEL P-304 manuals
Add to My Manuals
Save this manual to your list of manuals

Page 68 highlights

Prestige 304 Broadband Sharing Gateway with 4-Port Switch PPTP Protocol Overview PPTP is very similar to L2TP, since L2TP is based on both PPTP and L2F (Cisco's Layer 2 Forwarding). Conceptually, there are three parties in PPTP, namely the PNS (PPTP Network Server), the PAC (PPTP Access Concentrator) and the PPTP user. The PNS is the box that hosts both the PPP and the PPTP stacks and forms one end of the PPTP tunnel. The PAC is the box that dials/answers the phone calls and relays the PPP frames to the PNS. The PPTP user is not necessarily a PPP client (can be a PPP server too). Both the PNS and the PAC must have IP connectivity; however, the PAC must in addition have dial-up capability. The phone call is between the user and the PAC and the PAC tunnels the PPP frames to the PNS. The PPTP user is unaware of the tunnel between the PAC and the PNS. Diagram 4 PPTP Protocol Overview Microsoft includes PPTP as a part of the Windows OS. In Microsoft's implementation, the PC, and hence the Prestige, is the PNS that requests the PAC (the ANT) to place an outgoing call over AAL5 to an RFC 2364 server. Control and PPP Connections Each PPTP session has distinct control connection and PPP data connection. Call Connection The control connection runs over TCP. Similar to L2TP, a tunnel control connection is first established before call control messages can be exchanged. Please note that a tunnel control connection supports multiple call sessions. The following diagram depicts the message exchange of a successful call setup between a PC and an ANT. Diagram 5 Example Message Exchange between PC and an ANT D Appendix B

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
Prestige 304 Broadband Sharing Gateway with 4-Port Switch
D
Appendix B
PPTP Protocol Overview
PPTP is very similar to L2TP, since L2TP is based on both PPTP and L2F (Cisco's Layer 2 Forwarding).
Conceptually, there are three parties in PPTP, namely the PNS (PPTP Network Server), the PAC (PPTP
Access Concentrator) and the PPTP user.
The PNS is the box that hosts both the PPP and the PPTP stacks
and forms one end of the PPTP tunnel.
The PAC is the box that dials/answers the phone calls and relays the
PPP frames to the PNS.
The PPTP user is not necessarily a PPP client (can be a PPP server too). Both the
PNS and the PAC must have IP connectivity; however, the PAC must in addition have dial-up capability.
The phone call is between the user and the PAC and the PAC tunnels the PPP frames to the PNS.
The PPTP
user is unaware of the tunnel between the PAC and the PNS.
Diagram 4 PPTP Protocol Overview
Microsoft includes PPTP as a part of the Windows OS. In Microsoft's implementation, the PC, and hence the
Prestige, is the PNS that requests the PAC (the ANT) to place an outgoing call over AAL5 to an RFC 2364
server.
Control and PPP Connections
Each PPTP session has distinct control connection and PPP data connection.
Call Connection
The control connection runs over TCP.
Similar to L2TP, a tunnel control connection is first established
before call control messages can be exchanged.
Please note that a tunnel control connection supports
multiple call sessions.
The following diagram depicts the message exchange of a successful call setup between a PC and an ANT.
Diagram 5 Example Message Exchange between PC and an ANT