Home > Articles > Cisco > CCNA Routing and Switching

This chapter is from the book

Review Activities

Chapter Summary

  • The primary purpose of the core IPv6 protocol mirrors the same purpose of the IPv4 protocol. That core IPv6 protocol, as defined in RFC 2460, defines a packet concept, addresses for those packets, and the role of hosts and routers. These rules enable the devices to forward packets sourced by hosts, through multiple routers, so that they arrive at the correct destination host.
  • However, because IPv6 impacts so many other functions in a TCP/IP network, many more RFCs must define details of IPv6. Some other RFCs define how to migrate from IPv4 to IPv6. Others define new versions of familiar protocols or replace old protocols with new ones. For example:
    • Older OSPF Version 2 Upgraded to OSPF Version 3: The older OSPF version 2 works for IPv4 but not for IPv6, so a newer version, OSPF version 3, was created to support IPv6.
    • ICMP Upgraded to ICMP Version 6: ICMP worked well with IPv4 but needed to be changed to support IPv6. The new name is ICMPv6.
    • ARP Replaced by Neighbor Discovery Protocol: For IPv4, ARP discovers the MAC address used by neighbors. IPv6 replaces ARP with a more general Neighbor Discovery Protocol (NDP).
  • Although the term IPv6, when used broadly, includes many protocols, the one specific protocol called IPv6 defines the new 128-bit IPv6 address.
  • As with many functions of IPv6, IPv6 routing looks just like IPv4 routing from a general perspective, with the differences being clear only when you look at the specifics. IPv6 uses these ideas the same way as IPv4:
    • To be able to build and send IPv6 packets out an interface, end-user devices need an IPv6 address on that interface.
    • End-user hosts need to know the IPv6 address of a default router, to which the host sends IPv6 packets if the host is in a different subnet.
    • IPv6 routers deencapsulate and reencapsulate each IPv6 packet when routing the packet.
    • IPv6 routers make routing decisions by comparing the IPv6 packet’s destination address to the router’s IPv6 routing table; the matched route lists directions of where to send the IPv6 packet next.
  • IPv6 uses a convenient hexadecimal (hex) format for addresses. To make it more readable, IPv6 uses a format with 8 sets of 4 hex digits, with each set of 4 digits separated by a colon. For example:

    2340:1111:AAAA:0001:1234:5678:9ABC:1234

  • Two basic rules let you, or any computer, shorten or abbreviate an IPv6 address:
    • Inside each quartet of four hex digits, remove the leading 0s (0s on the left side of the quartet) in the three positions on the left. (Note: At this step, a quartet of 0000 will leave a single 0.)
    • Find any string of two or more consecutive quartets of all hex 0s, and replace that set of quartets with a double colon (::). The :: means “two or more quartets of all 0s.” However, you can use :: only once in a single address, because otherwise the exact IPv6 might not be clear.
  • To expand an IPv6 address back into its full unabbreviated 32-digit number, use two similar rules. The rules basically reverse the logic of the previous two rules.
    • In each quartet, add leading 0s as needed until the quartet has four hex digits.
    • If a double colon (::) exists, count the quartets currently shown; the total should be less than 8. Replace the :: with multiple quartets of 0000 so that 8 total quartets exist.
  • IPv6 uses a mask concept, called the prefix length, similar to IPv4 subnet masks. Similar to the IPv4 prefix-style mask, the IPv6 prefix length is written as a / followed by a decimal number. The prefix length defines how many bits of the IPv6 address defines the IPv6 prefix, which is basically the same concept as the IPv4 subnet ID.
  • Like IPv4, you can start with an IPv6 address and prefix length and find the prefix, with the same general rules that you use in IPv4. If the prefix length is /P, then use these rules:
    • Copy the first P bits.
    • Change the rest of the bits to 0.
  • When using a prefix length that happens to be a multiple of 4, you do not have to think in terms of bits but in terms of hex digits. A prefix length that is a multiple of 4 means that each hex digit is either copied or changed to 0. Just for completeness, if the prefix length is indeed a multiple of 4, the process becomes
    • Identify the number of hex digits in the prefix by dividing the prefix length (which is in bits) by 4.
    • Copy the hex digits determined to be in the prefix per the first step.
    • Change the rest of the hex digits to 0.

Review Questions

Answer these review questions. You can find the answers at the bottom of the last page of the chapter. For thorough explanations, see DVD Appendix C, “Answers to Review Questions.”

  1. Which of the following was a short-term solution to the IPv4 address exhaustion problem?
    1. IP version 6
    2. IP version 5
    3. NAT/PAT
    4. ARP
  2. A router receives an Ethernet frame that holds an IPv6 packet. The router then makes a decision to route the packet out a serial link. Which of the following statements is true about how a router forwards an IPv6 packet?
    1. The router discards the Ethernet data link header and trailer of the received frame.
    2. The router makes the forwarding decision based on the packet’s source IPv6 address.
    3. The router keeps the Ethernet header, encapsulating the entire frame inside a new IPv6 packet before sending it over the serial link.
    4. The router uses the IPv4 routing table when choosing where to forward the packet.
  3. Which of the following is the shortest valid abbreviation for FE80:0000:0000:0100:0000:0000:0000:0123?
    1. FE80::100::123
    2. FE8::1::123
    3. FE80::100:0:0:0:123:4567
    4. FE80:0:0:100::123
  4. Which of the following is the shortest valid abbreviation for 2000:0300:0040:0005:6000:0700:0080:0009?
    1. 2:3:4:5:6:7:8:9
    2. 2000:300:40:5:6000:700:80:9
    3. 2000:300:4:5:6000:700:8:9
    4. 2000:3:4:5:6:7:8:9
  5. Which of the following is the unabbreviated version of IPv6 address 2001:DB8::200:28?
    1. 2001:0DB8:0000:0000:0000:0000:0200:0028
    2. 2001:0DB8::0200:0028
    3. 2001:0DB8:0:0:0:0:0200:0028
    4. 2001:0DB8:0000:0000:0000:0000:200:0028
  6. Which of the following is the prefix for address 2000:0000:0000:0005:6000:0700:0080:0009, assuming a mask of /64?
    1. 2000::5::/64
    2. 2000::5:0:0:0:0/64
    3. 2000:0:0:5::/64
    4. 2000:0:0:5:0:0:0:0/64

Review All the Key Topics

Review the most important topics from this chapter, noted with the Key Topic icon. Table 25-6 lists these key topics and where each is discussed.

keytopic.jpg

Table 25-6.Key Topics for Chapter 25

Key Topic Element

Description

Page Number

List

Similarities between IPv4 and IPv6

614

List

Rules for abbreviating IPv6 addresses

617

List

Rules for expanding an abbreviated IPv6 address

618

List

Process steps to find an IPv6 prefix, based on the IPv6 address and prefix length

620

Complete the Tables and Lists from Memory

Print a copy of DVD Appendix M, “Memory Tables,” or at least the section for this chapter, and complete the tables and lists from memory. DVD Appendix N, “Memory Tables Answer Key,” includes completed tables and lists for you to check your work.

Definitions of Key Terms

After your first reading of the chapter, try to define these key terms, but do not be concerned about getting them all correct at that time. Chapter 30 directs you in how to use these terms for late-stage preparation for the exam.

IPv4 address exhaustion

IETF

NAT

CIDR

IP version 6 (IPv6)

OSPF version 3 (OSPFv3)

EIGRP version 6 (EIGRPv6)

prefix

prefix length

quartet

Additional Practice with IPv6 Address Abbreviations

For additional practice abbreviating IPv6 addresses:

  • DVD Appendix K, “Practice for Chapter 25: Fundamentals of IP Version 6,” has some additional practice problems listed.
  • Create your own problems using any real router or simulator. Get into the router CLI, into configuration mode, and configure a 32-digit unabbreviated IPv6 address. Then predict the shortest abbreviation. Finally, use the show ipv6 interface command to see if the router used the same abbreviation you used.

Pearson IT Certification Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Pearson IT Certification and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Pearson IT Certification products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.pearsonitcertification.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020