Answers to the Chapter 9 Q&A Section 427
7
Split horizon can cause reachability issues in Frame Relay networks. List two ways in
which you can deal with split horizon problems.
The two methods of dealing with split horizon issues are turning it off (not recommended)
and implementing subinterfaces.
8
If connecting to non-Cisco routers on the other side of a Frame Relay network, what must
be specified in the configuration?
If connecting in a multivendor Frame Relay environment, you must use the IETF
implementation of Frame Relay. This can be done using the encapsulation frame-relay
ietf command, or IETF can be specified on each PVC as needed.
9
Frame Relay subinterfaces can be created with two different personalities. What are those
personalities?
Point-to-point and multipoint are the personality options for Frame Relay subinterfaces.
10
In Frame Relay traffic shaping, what is CIR?
In Frame Relay traffic shaping, CIR is the average rate at which you want to transmit. This
is generally not the same as the CIR provided by the telco, which is the amount you want
to send in periods of noncongestion.
11
If CIR is 64,000 bps, what should the value of MinCIR be?
The recommended setting for MinCIR is one-half of CIR, so MinCIR should be 32,000
bps.
12
List the steps in defining a map class for Frame Relay traffic shaping.
First, create the map class at global config. Then, define the traffic parameters for the map
class. Finally, associate the map class with a VC or an interface.
13
In map-class configuration mode, what command enables the router to respond to BECN
requests?
frame-relay adaptive-shaping becn
14
In map class configuration mode, what command specifies the CIR if you want CIR set to
512000 bps?
frame-relay cir 512000
15
In periods of congestion, what is the percentage drop of throughput experienced with each
BECN?
The drop is 25 percent but does not exceed MinCIR.
16
You are concerned that LMI is not flowing between the router and the switch. What
command could you use to watch the real-time exchange of LMI traffic?
debug frame-relay lmi