Chap 13 - PPP Flashcards
Name 5 components of PPP.
- contains header and trailer
- supports synchronous and async links
- Protocol Type field in header allows multiple L3 protocols
- Built in authentication tools
- Control protocols for each higher layer protocol
What are the 2 main categories of control protocols?
- Link Control Protocols (LCP
- Network Control Protocols (NCP)
How many LCPs are used per link?
1
How many NCPs are used per link?
One for each L3 protocol
What are 4 functions that LCP performs?
- Looped link detection
- Error detection
- Multilink Support
- Authentication
How does the PAP process work?
Initialized by router wanting to be authenticated by sending username and password in clear text
How does CHAP work?
- Authenticating router sends CHALLENGE with shared Random Number
- Router who wants to be authenticated creates and sends HASH based on username, password and shared Random Number
- Authenticating router compares received Hash with Hash it created. If a match then replies with PASS.
What happens if authentication fails?
PPP leaves the interface in an Up/Down state
What is CHAP’s one-way hash algorithm called?
MD5
On the authenticating router what input goes into the HASH
- Username
- Password
- Shared random number
What command takes an HDLC link and changes it to PPP?
encapsulation ppp
Do IP addresses need to be configured for PPP to work?
No
What are the steps for configuring PPP with CHAP?
- username (remote_router_hostname) password mypass
- int s0/0
- encapsulation ppp
- ppp authentication chap
What are 2 ways to tell if CHAP authentication has failed?
- interface in up/down state
- show ppp all
What are the steps for configuring PPP with PAP
- username (remote_router_sent-username) password (remote_router_sent-username_password)
- int s0/0
- encapsulation ppp
- ppp authentication pap
- ppp pap sent-username (local_router_hostname) password (local_router_password)