Fig. 33.1 – Westermo RedFox Series User Manual
Page 753
Westermo OS Management Guide
Version 4.17.0-0
Link Establishment Phase
(Link Control Protocol)
PAP, CHAP, EAP, ...
Authentication Phase
Compression and encryption
negotiation phase
(Compression Control
Protocol)
Configuration Phase
Network Layer Protocol
(IP Control Protocol)
depending on PPP type
Message exchange
(PPPoE, L2TP/PPTP
PPP over serial/modem)
PPP protocol handshakes
establishment"
"Low level link
PPP
"client"
PPP
PPP LCP
message exchange
PPP Auth. Protocol
message exchange
message exchange
PPP IPCP
PPP CCP
message exchange
"server"
Time
"Pre−PPP"
Figure 33.1: PPP Connection Establishment Phases
send LCP Echo Request/Reply messages, to verify connectivity once the link
is up. As of WeOS v4.17.0 the LCP Echo Interval is 20 seconds (fixed), and
the link is considered down after failing to receive three LCP responses.
❼ PPP Authentication Phase: During the Link Establishment phase, the peers
can negotiate the use (and type) of authentication. See
for
more information on WeOS support for PPP authentication.
❼ Compression and Encryption Negotiation Phase: After the Link Establish-
ment and Authentication phases, the PPP peers can use the PPP compres-
sion control protocol (CCP[
]) to negotiate link layer compression or en-
cryption (typically the Microsoft Point-To-Point Encryption (MPPE) Protocol[
See
for more information on WeOS support for PPP encryption.
As of WeOS v4.17.0 PPP link layer compression is not supported.
❼ Network Control Protocol Phase: Once the link has been established via
LCP, and the optional authentication and compression handshakes are car-
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