Chap 13 - PPP Flashcards

1
Q

Name 5 components of PPP.

A
  • 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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 2 main categories of control protocols?

A
  • Link Control Protocols (LCP
  • Network Control Protocols (NCP)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How many LCPs are used per link?

A

1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How many NCPs are used per link?

A

One for each L3 protocol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are 4 functions that LCP performs?

A
  • Looped link detection
  • Error detection
  • Multilink Support
  • Authentication
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does the PAP process work?

A

Initialized by router wanting to be authenticated by sending username and password in clear text

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does CHAP work?

A
  • 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.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens if authentication fails?

A

PPP leaves the interface in an Up/Down state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is CHAP’s one-way hash algorithm called?

A

MD5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

On the authenticating router what input goes into the HASH

A
  • Username
  • Password
  • Shared random number
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What command takes an HDLC link and changes it to PPP?

A

encapsulation ppp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Do IP addresses need to be configured for PPP to work?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the steps for configuring PPP with CHAP?

A
  • username (remote_router_hostname) password mypass
  • int s0/0
    • encapsulation ppp
    • ppp authentication chap
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are 2 ways to tell if CHAP authentication has failed?

A
  • interface in up/down state
  • show ppp all
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the steps for configuring PPP with PAP

A
  • 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)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are 2 ways to tell if PAP authentication failed?

A
  • interface in up/down state
  • show ppp all
17
Q

What is the difference between how CHAP passwords are configured vs. PAP passwords?

A
  • CHAP requires password to match on both ends
  • finds correct username/password combination to send based on the username match
  • PAP relies on the sent-username interface command for username and password.
18
Q

What is the default load balancing method used on 2 equal-metric serial links?

A

Per destination

19
Q

How does MLPPP do load balancing?

A

It fragments the packet with each fragment having its own PPP header/trailer.

20
Q

What are the commands to configure a serial interface for MLPPP?

A
  • int s0/0
    • no ip address
    • encap ppp
    • ppp multilink
    • ppp multilink group 1
    • authentication (if configured)
21
Q

What are the commands to configure a multilink interface for MLPPP?

A
  • int mu1
    • ip address 1.1.1.1 255.255.255.0
    • encap ppp
    • ppp multilink
    • ppp multilink group 1
22
Q

When configuring MLPPP, which parameters must match on both ends of the link?

A
  • the multilink interface number (mu1)
  • the multilink group number
23
Q

For MLPPP, which 3 commands are the same on both physical interfaces and multilink interface?

A
  • encap ppp
  • ppp multilink
  • ppp multilink group 1
24
Q

What 2 show commands verify multilink is working?

A
  • show interfaces mu1
  • show ppp multilink
25
Q

What layer is affected if interface status is down/down

A

Layer 1

26
Q

What layer is affected if interface status is up/down

A

Layer 2

27
Q

What layer is affected if interface status is up/up?

A

Layer 3 (could be mismatched IP subnets)

28
Q

What is the remote interface status if the remote end is admin’ed down?

A

down/down

29
Q

What are the possible causes when the remote router interface is down/down?

A
  • local interface admin’ed down
  • bad/unplugged cable
  • misconfigured or bad CSU
  • Telco problems
30
Q

What are possible causes if both routers are up/down?

A
  • mismatched encapsulation
  • ppp authentication failure
31
Q

What is the possible cause if the local router is up/up but the remote router is up/down?

A

KeepAlives disabled on the local router when using HDLC (ppp has its own keepalives)

32
Q

What will happen if encap is PPP and the two routers are in different subnets?

A
  • pings will still work
  • routing neighbor relationship won’t form
33
Q

What is the difference between a Connected Route and a Local Route?

A
  • Connected Route gets subnet mask from interface
  • Local Route always has /32