A Practical Guide to Advanced Networking: IPv6

Dec 11, 2012

📄 Contents

␡

⎙ Print

< Back Page 4 of 8 Next >

This chapter is from the book 

Practical Guide to Advanced Networking, A, 3rd Edition

Learn More Buy

8-4. Configuring a Router for IPv6

Not every piece of networking equipment is IPv6-capable, and this must be verified before implementing IPv6. IPv6-capable equipment can operate in the IPv4 and IPv6 environment. IPv6 relies heavily on multicast messages for enabling a lot of functions; therefore, the network switches must be able to support IPv6 multicast functions as well. In IPv4, IGMP (Internet Group Management Protocol) is used for determining which computers should join a multicast group. However, IGMP is no longer used in IPv6. For multicast group management, IPv6 uses Multicast Listener Discovery (MLD) instead. Similar to IGMP in IPv6, MLD snooping enables the switches to listen to MLD packets to determine how to efficiently forward multicast packets to specific listeners on specific ports.

Today, most routers are IPv6-capable. Those that are not might just require a software upgrade. On Cisco routers, IPv6 is not enabled automatically. To enable IPv6 unicast packet forwarding on Cisco routers, the global command ipv6 unicast-routing is entered. The following is the sequence of commands required to enable IPv6 unicast-routing:

Router# conf t
Router(config)#
Router(config)# ipv6 unicast-routing

The ipv6 unicast-routing command only activates the IPv6 forwarding mechanism on the routers. However, IPv6 is still not yet enabled on a specific interface. To enable IPv6 on a specific interface, you must enter the ipv6 enable command. The following example shows how to enable IPv6 on a gigabitethernet 3/1 interface. This step requires that the interface must first be selected. In this case, the command int Gig3/1 is entered from the (config)# prompt. The prompt changes to (config-if)# and the command ipv6 enable is entered:

int Gig3/1
Router(config)# int Gig3/1
Router(config-if)# ipv6 enable

For Cisco routers, enabling IPv6 on the interface automatically configures the link-local address for that interface. The link-local address can only communicate with the IPv6 devices on the same network link.

The command show running-config is used to verify the IPv6 configuration. The use of this command is next demonstrated and a portion of the running configuration for interface GigabitEthernet 3/1 is provided:

Router#show running-config
.
.
!
interface GigabitEthernet3/1
 no ip address
 ipv6 enable
!

Also, the command show ipv6 interface can be used to show the state of the IPv6 configuration on the interface. This command shows the IPv6 of the interface. In the following example, it shows that IPv6 is enabled on the interface gigabitEtheret3/1. It shows the interface has a link-local address, but not the global address. Along with that the IPv6 network discovery protocol information is shown:

Router#show ipv6 interface gigabitEthernet 3/1
GigabitEthernet3/1 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::217:DFFF:FEF5:1000
  No global unicast address is configured
  Joined group address(es):
    FF02::1
    FF02::2
    FF02::1:FFF5:1000
  MTU is 1500 bytes
  ICMP error messages limited to one every 100 milliseconds
  ICMP redirects are enabled
  Output features: HW Shortcut Installation
  ND DAD is enabled, number of DAD attempts: 1
  ND reachable time is 30000 milliseconds
  ND advertised reachable time is 0 milliseconds
  ND advertised retransmit interval is 0 milliseconds
  ND router advertisements are sent every 200 seconds
  ND router advertisements live for 1800 seconds
  ND advertised default router preference is Medium
  Hosts use stateless autoconfig for addresses.

The IPv6 global address can be configured on the interface by using the command ipv6 address ipv6 interface address issued from the (config-if)# prompt. There are two ways to program the IPv6 interface address. One is to specify the entire 128-bit IPv6 address followed by the prefix length. Another way is to specify a 64-bit prefix and to use the eui-64 option. Using the option eui-64 allows the router to choose its own host identifier (right most 64-bits) from the EUI-64 (Extended Universal Identifier-64) of the interface. The following example uses the IPv6 address of 2001:DB88:FEED:BEEF::1 on the router interface. This has a 64-bit network prefix of 2001:DB88:FEED:BEEF.

Router(config)# int Gig3/1
Router(config-if)# ipv6 address 2001:DB88:FEED:BEEF::1/64

Next, the command show ipv6 interface gigabitEthernet 3/1 is used to display the configuration of the Gig3/1 interface. This time the command shows that the interface gigabitEthernet 3/1 now has an IPv6 global address assigned to it, which is 2001:DB8:FEED:BEEF::1:

Router#show ipv6 interface gigabitEthernet 3/1
GigabitEthernet3/1 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::217:DFFF:FEF5:1000
  Global unicast address(es):
  2001:DB8:FEED:BEEF::1, subnet is 2001:DB8:FEED:BEEF::/64
  Joined group address(es):
    FF02::1
    FF02::2
    FF02::1:FF00:1
    FF02::1:FFF5:1000
  MTU is 1500 bytes
  ICMP error messages limited to one every 100 milliseconds
  ICMP redirects are enabled
  Output features: HW Shortcut Installation
  ND DAD is enabled, number of DAD attempts: 1
  ND reachable time is 30000 milliseconds
  ND advertised reachable time is 0 milliseconds
  ND advertised retransmit interval is 0 milliseconds
  ND router advertisements are sent every 200 seconds
  ND router advertisements live for 1800 seconds
  ND advertised default router preference is Medium
  Hosts use stateless autoconfig for addresses.

Now that IPv6 is enabled on the router, the router can begin to participate in the IPv6 functions. The router plays a key role in the stateless autoconfiguration of an IPv6 network. An IPv6 router uses the neighbor discovery (ND) protocol to periodically advertise information messages on the links to which they are connected. These are ICMPv6 messages of the type Router Advertisement (RA). One parameter of the router advertisements is the IPv6 network prefix for the link that can be used for host autoconfiguration. Upon receiving RA messages, an unconfigured host can build its global unicast address by prepending the advertised network prefix to its generated unique identifier just like in the link-local address case.

Another way for a host to autoconfigure itself is by sending router solicitation messages to the connected routers. These messages are sent to ask routers to send an immediate RA message on the local link, so the host can receive the autoconfiguration information without having to wait for the next schedule RA. Note: The time interval between RA messages is configurable. By default, router advertisements are sent every 200 seconds in Cisco routers.

As a result, the global unicast address of every machine on this network is the combination of the network prefix of 2001:DB8:FEED:BEEF and the self-generated interface identifier for that machine. Both Figure 8-11 and Figure 8-12 show two IPv6 addresses with the 2001:DB8:FEED:BEEF prefix. There are two IPv6 addresses. One is a global unicast address and another is a random generated identifier as part of the privacy identifier. This was discussed earlier in this section (see Privacy Extensions for Stateless Autoconfiguration). Microsoft calls this random identifier IPv6 a “temporary IPv6 address.” This is shown to be a temporary address in Windows 7.

Figure 8-11. Windows XP—ipconfig result with an IPv6 global unicast address

Figure 8-12. Windows 7—ipconfig result with an IPv6 global unicast address

In Windows XP, both of these are presented as IP addresses. Of course, we can tell that one is a modified EUI-64 format, and the other one is randomly generated. An IPv6 address with ff:fe in the middle indicates the EUI-48 to EUI-64 transform. On Mac OS X, no random identifier is used. The global unicast address is the product of the modified EUI-64 format, as shown in Figure 8-13.

Figure 8-13. Mac OS X—ipconfig result with an IPv6 global unicast address

Throughout this chapter, the IPv6 prefix used is 2001:DB8::/32. This is a special range designated by the IANA to be used for any testing or documentation. This IPv6 prefix cannot be used nor can it be routed on the Internet.

With the global unicast address, the machine is now reachable from anywhere on the IPv6 network. However, it is a daunting task to remember the IPv6 global unicast address. It is not practical to use the long 128-bits address. This required a DNS server that can translate a host name to an IPv6 address. The DNS record for IPv6 is called AAAA (Quad A) record.

< Back Page 4 of 8 Next >

🔖 Save To Your Account

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.

Privacy Notice

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

Email Address