434 Understanding IPv6, Second Edition

Yes. The IPv6 router running Windows Server 2008 will include the 2001:db8:0:1a4c::/64 prefix in a Route Information option for the Router Advertisement sent on the 2001:db8:0:90b5::/64 subnet. Hosts on the 2001:db8:0:90b5::/64 subnet add a route to their local IPv6 routing table for the 2001:db8:0:1a4c::/64 prefix.

Chapter 11: IPv6 Transition Technologies

1.Describe the difference between migration and coexistence.

Migration is the equipping and configuration of all nodes to replace one protocol (IPv4) with another (IPv6). Coexistence is allowing both types of protocols to maintain connectivity—an advantage while migration is occurring.

2.How does an IPv4-only host communicate with an IPv6-only host?

It communicates by using an Application or Transport layer gateway or proxy that translates or proxies IPv4 traffic to IPv6 traffic, and vice versa. The PortProxy component of the IPv6 protocol for Windows Server 2008 and Windows Vista is an example of a Transport layer proxy.

3.What is an IPv4-mapped address used for?

An IPv4-mapped address is used by an IPv6 implementation to internally represent IPv4only hosts and IPv4 addresses.

4.Is the IPv6 protocol for Windows Server 2008 and Windows Vista a dual IP layer? Why or why not?

Yes. The IPv6 protocol for Windows Server 2008 and Windows Vista includes single implementations of TCP and UDP that operate over both IPv4 and IPv6.

5.How are the source and destination addresses in the IPv4 header determined for IPv6- over-IPv4 tunnel traffic?

For configured tunneling, the source and destination IPv4 addresses are determined from the manually configured tunnel endpoints.

For automatic tunneling, the destination IPv4 address is derived from the next-hop address for the packet, which contains an embedded IPv4 address that is determined by the tunneling interface. The source address is the best source address to use to reach the already determined destination IPv4 address.

6.What is the Netsh command to enable the proxying of TCP connection data between an IPv6-only host and an IPv4-only service that is running on the PortProxy computer and listening on TCP port 32175?

netsh interface portproxy add v6tov4 listenport=32175 connectport=32175

7.Why might you have to manually add A or AAAA DNS records to help facilitate communication between IPv4-only nodes and IPv6-only nodes when using PortProxy?

For communication initiated by the IPv4-only node, the name of the IPv6-only node must resolve to an IPv4 address that is assigned to an interface of the PortProxy computer. This might require the addition of an A record. For communication initiated by the IPv6-only node, the name of the IPv4-only node must resolve to an IPv6 address assigned to an interface of the PortProxy computer. This might require the addition of an AAAA record.

Chapter 12: ISATAP

1.Describe the intended use of the ISATAP IPv6 transition technology.

ISATAP is intended to provide unicast IPv6 connectivity between IPv6/IPv4 hosts across an IPv4 intranet.

2.How can you recognize an ISATAP address?

You can recognize an ISATAP address from the “5efe” in the sixth block of the address and the dotted decimal notation of an IPv4 address in the seventh and eighth blocks of the address.

3.How are the source and destination addresses in the encapsulating IPv4 header determined for ISATAP traffic?

The ISATAP tunneling interface determines the destination IPv4 address from the last 32-bits of the next-hop address corresponding to the destination ISATAP address of the packet. The source address is the best source address to use to reach the already determined destination IPv4 address.

4.Define the required and optional roles of an ISATAP router.

Required: An ISATAP router must advertise one or more address prefixes that are assigned to the logical ISATAP subnet.

Optional: An ISATAP router can forward IPv6 packets between the logical ISATAP subnet and other IPv6 subnets.

5.List and describe the steps that a Windows Vista–based ISATAP host with a single LAN interface goes through to perform router discovery for its ISATAP tunneling interface.

Step 1. The IPv6 component in Windows Vista creates ISATAP tunneling interfaces as needed and assigns link-local ISATAP addresses to them.

Step 2. The IPv6 component in Windows Vista attempts to resolve the name ISATAP to an IPv4 address using built-in name resolution techniques.

436 Understanding IPv6, Second Edition

Step 3. When the name ISATAP is resolved to an IPv4 address, IPv6 sends an IPv4encapsulated Router Solicitation message to the ISATAP router.

Step 4. When the IPv6 component in Windows Vista receives the Router Advertisement message, it configures additional ISATAP addresses and routes based on the message contents.

In Windows Server 2008 and Windows Vista with SP1, the steps are in the order 2, 1, 3, 4.

6.To reach a native IPv6 host, IPv6 packets from an ISATAP host must traverse 7 IPv4 routers on the ISATAP subnet and 3 native IPv6 routers on the IPv6-capable portion of the intranet. If the IPv6 packets were sent by the ISATAP host with a Hop Limit field of 128, what is the value of the Hop Limit field when the packets arrive at the destination?

124 (1 for the ISATAP router and 3 more for the native IPv6 routers)

7.A network administrator needs to begin experimenting with IPv6 connectivity on his company’s IPv4-only intranet. Describe how the network administrator can configure a computer running Windows Server 2008 as an ISATAP router to immediately turn the entire IPv4-only intranet into a logical IPv6 subnet.

Use the following commands to enable advertising on the ISATAP interface and advertise an address prefix for the logical ISATAP subnet:

netsh interface ipv6 set interface ISATAPInterfaceNameOrIndex advertise=enabled

netsh interface ipv6 add route Address/PrefixLength ISATAPInterfaceNameOrIndex publish=yes

Then add A records to the appropriate DNS domains to resolve the name ISATAP to the IPv4 address of the computer running Windows Server 2008.

Chapter 13: 6to4

1.Describe the intended use of the 6to4 IPv6 transition technology.

6to4 is intended to provide unicast IPv6 connectivity between IPv6/IPv4 hosts in IPv6capable sites across the IPv4 intranet and to provide connectivity to the IPv6 Internet.

2.How can you recognize a 6to4 address? 6to4 addresses begin with 2002.

3.How are the source and destination addresses in the encapsulating IPv4 header determined for 6to4-tunneled traffic?

The 6to4 tunneling interface determines the destination IPv4 address from the second and third blocks of the next-hop address corresponding to the destination 6to4 address of the packet. The source address is the best source address to use to reach the already determined destination IPv4 address.

4.To reach a native IPv6 host on the IPv6 Internet, IPv6 packets from a 6to4 host must traverse 3 native IPv6 routers on an intranet, 13 IPv4 routers on the IPv4 Internet, and 6 native IPv6 routers on the IPv6 Internet. If the IPv6 packets were sent by the 6to4 host with a Hop Limit field of 128, what is the value of the Hop Limit field when the packets are received at the destination?

118 (1 for the IPv4 Internet and 9 more for the native IPv6 routers on the intranet and the IPv6 Internet)

5.A network administrator needs to begin experimenting with IPv6-only Web sites on the IPv6 Internet. Describe how the network administrator can configure a computer running Windows Server 2008 as a 6to4 router to immediately obtain connectivity to the IPv6 Internet.

Configure the computer running Windows Server 2008 with a public IPv4 address, and enable Internet Connection Sharing on the Internet interface.

Chapter 14: Teredo

1.Describe the intended use of the Teredo IPv6 transition technology.

Teredo is intended to provide unicast IPv6 connectivity between IPv6/IPv4 hosts that are connected to the IPv4 intranet and to provide connectivity to the IPv6 Internet.

2.How can you recognize a Teredo address? A Teredo address begins with 2001::.

3.How are the source and destination addresses in the encapsulating IPv4 header determined for Teredo-tunneled traffic to another Teredo client?

The Teredo tunneling interface determines the destination IPv4 address from the last 32 bits of the next-hop address corresponding to the destination address of the packet. The source address is the best source address to use to reach the already determined destination IPv4 address.

4.Why are portions of the Teredo address obscured?

To prevent “smart” NATs from translating the internal and external address and port numbers of traffic that the NAT forwards.

5.What is the difference between a Teredo relay and a Teredo host-specific relay?

A Teredo relay is an IPv6/IPv4 router that can forward packets between Teredo clients on the IPv4 Internet and IPv6 hosts on the IPv6 Internet. A Teredo host-specific relay is an IPv6/IPv4 node that has an interface and connectivity to both the IPv4 Internet and the IPv6 Internet and can communicate directly with Teredo clients over the IPv4 Internet, without the need for an intermediate Teredo relay.