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Answers to the Chapter 8 Q&A Section 771
19
What show commands list Frame Relay information about mapping? In what instances
will the information displayed include the Layer 3 addresses of other routers?
show frame-relay map. The mapping information includes Layer 3 addresses when
multipoint subinterfaces are used or when no subinterfaces are used. The two cases in
which the neighboring routers' Layer 3 addresses are shown are the two cases in which
Frame Relay acts like a multiaccess network. With point-to-point subinterfaces, the logic
works like a point-to-point link, where the next router's Layer 3 address is not important
to the routing process.
20
True or false: The no keepalive command on a Frame Relay serial interface causes no
further Cisco proprietary keepalive messages to be sent to the Frame Relay switch.
False. This command stops LMI status inquiry messages from being sent. If the switch is
expecting these, the switch could take down the PVCs to this DTE. Be careful--this is
exactly the type of tricky wording on the exam. The messages do not go between the two
routers over Frame Relay, but the Cisco keepalive message is not sent on true point-to-
point links.
21
What debug options will show Inverse ARP messages?
debug frame-relay events, as shown in Example 8-19 on page 561.
22
True or false: The Frame Relay map configuration command allows more than one Layer
3 protocol address mapping on the same configuration command.
False. The syntax allows only a single network layer protocol and address to be
configured.
23
What do the letters in ISDN represent? What about BRI and PRI?
Integrated Services Digital Network. Basic Rate Interface. Primary Rate Interface. BRI is
the most likely to be on the exam.
24
Define the term function group. List two examples of function groups.
A function group is a set of ISDN functions that need to be implemented by a device. NT1,
NT2, TE1, TE2, and TA are all function groups.
25
Define the term reference point. List two examples of reference points.
A reference point is an interface between function groups. R, S, T, and U are reference
points. S and T are combined in many cases and then called the S/T reference point.
Reference points refer to cabling, which implies the number of wires used. In particular,
the S and T points use a four-wire interface; the U interface uses a two-wire cable.
apA.fm Page 771 Monday, March 20, 2000 5:24 PM