This chapter covers the following subjects:
Frame Relay Protocols
Frame Relay Configuration
Frame Relay is the most popular WAN technology used today, so it's no surprise that Frame Relay is an important topic on the ICND exam. This chapter reviews the details of how Frame Relay accomplishes its goal of delivering frames to multiple WAN-connected sites.
Frame Relay most closely compares to the OSI data link layer (Layer 2). If you remember that the word "frame" describes the data link layer protocol data unit (PDU), it will be easy to remember that Frame Relay relates to OSI Layer 2. Like other data-link protocols, Frame Relay can be used to deliver packets (Layer 3 PDUs) between routers. Frame Relay protocol headers and trailers are simply used to let a packet traverse the Frame Relay network, just like Ethernet headers and trailers are used to help a packet traverse an Ethernet segment.
This chapter describes the Frame Relay protocol details, along with the associated configuration.
"Do I Know This Already?" Quiz
The purpose of the "Do I Know This Already?" quiz is to help you decide if you need to read the entire chapter. If you intend to read the entire chapter, you do not necessarily need to answer these questions now.
The ten-question quiz, derived from the major sections in the "Foundation Topics" section, helps you determine how to spend your limited study time.
Table 11-1 outlines the major topics discussed in this chapter and the "Do I Know This Already?" quiz questions that correspond to those topics.
Table 11-1 "Do I Know This Already?" Foundation Topics Section-to-Question Mapping
|
Foundations Topics Section |
Questions Covered in This Section |
|
Frame Relay Concepts |
1–6 |
|
Frame Relay Configuration |
7–10 |
CAUTION
The goal of self-assessment is to gauge your mastery of the topics in this chapter. If you don't know the answer to a question or you're only partially sure of the answer, you should mark this question as wrong for purposes of the self-assessment. Giving yourself credit for an answer you guess correctly skews your self-assessment results and might give you a false sense of security.
Which of the following defines a protocol used between the Frame Relay DTE and the Frame Relay switch in the service provider's network?
-
VC
-
cIR
-
LMI
-
Q.921
-
dLCI
-
fRF.5
-
encapsulation
-
None of the above
Which of the following defines a protocol or feature that matters to what the provider might do inside its network but that is transparent to the DTE/router using the Frame Relay service?
-
VC
-
cIR
-
LMI
-
dLCI
-
Q.921
-
fRF.5
-
encapsulation
-
None of the above
What does DLCI stand for?
-
data Link Connection Identifier
-
data Link Connection Indicator
-
data Link Circuit Identifier
-
data Link Circuit Indicator
-
None of the above
Imagine two Cisco routers, R1 and R2, using a Frame Relay service. R1 connects to a switch that uses LMI type ANSI T1.617, and R2 connects to a switch that uses ITU Q.933a. What can R1 and R2 configure for the LMIs to work correctly?
-
aNSI and ITU
-
T1617 and q933
-
aNSI and q933
-
T1617 and ITU
-
This won't work with two different types.
-
No configuration is needed.
FredCo has five sites, with routers connected to the same Frame Relay network. Virtual circuits (VCs) have been defined between each pair of routers. What is the fewest subnets that FredCo could use on the Frame Relay network?
1
2
3
4
5
6
7
8
9
10
BarneyCo has five sites, with routers connected to the same Frame Relay network. VCs have been defined between each pair of routers. Barney, the president of the company, will fire anyone who configures Frame Relay without using point-to-point subinterfaces. What is the fewest subnets that BarneyCo could use on the Frame Relay network?
1
4
8
10
12
15
BettyCo has five sites, with routers connected to the same Frame Relay network. VCs have been defined between each pair of routers. Betty, the president of the company, will fire anyone who configures anything that could just as easily be left as a default. Which of the following configuration commands, configured for the Frame Relay network, would get the engineer fired?
ip address
encapsulation
lmi-type
frame-relay map
inverse-arp
WilmaCo has some routers connected to a Frame Relay network. R1 is a router at a remote site, with a single VC back to WilmaCo's headquarters. The R1 configuration currently looks like this:
-
no ip address
-
interface-dlci
-
no encapsulation
-
encapsulation frame-relay
-
frame-relay interface-dlci
WilmaCo has another network, with a main site router that has ten VCs connecting to the ten remote sites. Wilma now thinks that multipoint subinterfaces are even cooler than point-to-point. The current main site router's configuration looks like this:
interface-dlci 101 110
interface dlci 101-110
Ten different interface-dlci commands
frame-relay interface-dlci 101 110
frame-relay interface dlci 101-110
Ten different frame-relay interface-dlci commands
Which of the following commands lists the information learned by Inverse ARP?
show ip arp
show arp
show inverse arp
show frame-relay inverse-arp
show map
show frame-relay map
interface serial 0/0 ip address 10.1.1.1 255.255.255.0 encapsulation frame-relay
Wilma, the president, has heard that point-to-point subinterfaces are cool, and she wants you to change the configuration to use a point-to-point subinterface. Which of the following commands do you need to use to migrate the configuration?
interface serial 0/0 ip address 172.16.1.1 255.255.255.0 encapsulation frame-relay
Wilma wants you to change the configuration to use a multipoint subinterface. Which of the following do you need to use to migrate the configuration? (Note: DLCIs 101 through 110 are used for the ten VCs.)
The answers to the "Do I Know This Already?" quiz appear in Appendix A. The suggested choices for your next step are as follows:
8 or less overall score—Read the entire chapter. This includes the "Foundation Topics," "Foundation Summary," and "Q&A" sections.
9 or 10 overall score—If you want more review on these topics, skip to the "Foundation Summary" section and then go to the "Q&A" section. Otherwise, move to the next chapter.