background image
766 Appendix A: Answers to the "Do I Know This Already?" Quizzes and Q&A Sections
Answers to the Chapter 8 "Do I Know This Already?" Quiz
1
Can PPP perform dynamic assignment of IP addresses? If so, is the feature always
enabled?
PPP's IPCP protocol can assign an IP address to the device on the other end of the link.
This process is not required and is not performed by default. PPP usually does address
assignment for dial access, such as when a user dials an Internet service provider.
2
Create a configuration to enable PPP on serial 0 for IP and IPX. Make up IP and IPX
Layer 3 addresses as needed.
interface serial 0
ip addr 1.1.1.1 255.255.255.0
ipx network 1
encapsulation ppp
encapsulation ppp is all that is needed for PPP. Having IP and IPX enabled causes PPP
to enable the control protocols for each.
3
CHAP configuration uses names and passwords. Given Routers A and B, describe what
names and passwords must match in the respective CHAP configurations.
Router A has name B and a corresponding password configured. Router B has name A and
the same password configured. The names used are the host names of the routers unless
the CHAP name is configured.
4
What field has Cisco added to the HDLC header, making it proprietary?
A Protocol Type field has been added to allow support for multiprotocol traffic. HDLC
was not architected to allow for multiprotocol support originally.
5
Explain the purpose of Inverse ARP. Explain how Inverse ARP uses Frame Relay
broadcasts.
A router discovers the Layer 3 address(es) of a router on the other end of a VC when that
other router sends an Inverse ARP message. The message is not a broadcast. Broadcasts
are not supported over Frame Relay.
6
Would a Frame Relay switch connected to a router behave differently if the IETF option
were deleted from the encapsulation frame-relay ietf command on that attached router?
Would a router on the other end of the VC behave any differently if the same change were
made?
The switch does not behave differently. The other router, however, must also use IETF
encapsulation; otherwise, the routers will not be looking at the correct fields to learn the
packet type. The IETF-defined headers include the Protocol Type field options.
apA.fm Page 766 Monday, March 20, 2000 5:24 PM