2. Step 2: Check and verify the pap authentication between RA and RB.
Step 3: Test the connectivity between RB and RC.
4. Step 4 Check and verify CHAP authentication between RB and RC.
Extended data:
Workflow of ppp protocol
When a user dials up to access an ISP, the router's modem will confirm the dialing and establish a physical connection (bottom-up). The PC sends a series of LCP packets (encapsulated in multiple PPP frames) to the router.
These packets and their responses select some PPP parameters and configure the network layer (if PAP or CHAP authentication is required before). NCP assigns a temporary IP address to the newly accessed PC, making it a host on the Internet.
When the communication is completed, NCP releases the network layer connection and takes back the originally assigned IP address. Then, LCP releases the data link layer connection. Finally, release the physical layer connection.
Baidu encyclopedia -PPP protocol