CH13: Internet Protocol Version 6 (IPv6)
How many IPv4 addresses are available? How many of those can be assigned to devices?
About 4.3 billion are available, but there really are only about 250 million addresses that can be assigned to devices.
What is a Multicast Address?
As in IPv4, packets addressed to a Multicast Address are delivered to all interfaces identified by the multicast address. They're one-to-many addresses. In an IPv6 address, they always start with FF.
What is Autoconfiguration in the IPv6 environment?
Autoconfiguration allows devices on a network to address themselves with a link-local unicat address. This process happens through first learning the prefix information from the router and then appending the device's own interface address as the interface ID. The interface ID is the device's physical MAC address. Since the interface ID is 64 bits, the extra 16 bits are padding in the middle "FFFE". Finally the 7th bit in the address gets changed to identify whether it is globally unique (1) or locally unique (0).
What IPv6 multicast addresses does OSPFv3 use?
FF02::5 and FF02::6
What is the IPv6 multicast address for RIPng?
FF02::9
What is the IPv6 multicast address for EIGRP?
FF02::A
What is the process that DHCPv6 goes through in IPv6?
First, the host performs autoconfiguration to find its IP address by sending out an RS. The router sends back an RA saying whether or not a DHCP is available for use. If a router isn't found, the client will respond by sending out a DHCP solicit message (a multicast message addressed to all DHCP agents).
What is a Global Unicast Address?
Global Unicast Addresses are your typical publicly routable addresses, and they're the same as they are in IPv4.
What are the special (or reserved addresses) in IPv6?
- 2000::/3 - Global Unicast Address range - FC00::/7 - Unique Local Unicast range - FE80::/10 - Link-Local Unicast range - FF00::/8 - Multicast range - 3FFF:FFFF::/32 and 2001:0DB8::/32- Reserved for examples and documentation - 2002::/16 - Used with 6to4
What are the three ways organizations are handling the migration from IPv4 to IPv6?
- Dual-stacking - 6to4 Tunneling - NAT-PT
What are two IPv4 add-ons that have become standardized on IPv6?
- IPSec: Provides end-to-end security - Mobility: Allows a device to roam from one network to another without dropping connections
What are the different address types in IPv6?
- Unicast - Global Unicast Addresses - Link-Local Addresses - Unique Local Addresses - Multicast - Anycast
What are some advancements that we have used with IPv4 to increase the amount of usable IP addresses?
- Variable Length Subnet Masks (VLSM) and Classless Inter-Domain Routing (CIDR) - Network Address Translation (NAT)
What are the rules about shortening an IPv6 address and what is an example showing how it can be used the best way?
- You can only replace one contiguous block of zeros in an address with double-colons. -For any other bytes that are all 0s, you can reduce them by placing only one zero - You can drop any leading zeros in each of the individual blocks - 2001:0000:0000:0012:0000:0000:1234:56ab - 2001::12:0:0:1234:56ab
What does the MAC address 0060.d673.1987 look like as an interface ID?
0260.d6FF.FE73.1987 - Why the 2? For padding, the 7th bit in the address gets changed to identify whether it is globally unique (1) or locally unique (0).
How would 192.168.100.1 be written in a mixed IPv6/IPv4 environment?
0:0:0:0:0:0:192.168.100.1
What is the two-step process that a host uses to go through stateless autoconfiguration?
1. First, the host needs the prefix information, so it sends a router solicitation (RS) request for it. 2. The router answers back with the required prefix information via a router advertisement (RA). RA messages are sent on a periodic basis, but the host sends the RS for an immediate response so it doesn't have to wait until the next scheduled RA to get what it needs.
How long is an IPv6 address?
128 bits (four times the size of IPv4 addresses)
What is an example of an IP address (non-shortened) and what does each section mean?
2001:0db8:3c4d:0012:0000:0000:1234:56ab - 2001:0db8:3c4d is the Global prefix - 0012 is the Subnet - 0000:0000:1234:56ab is the Interface ID
How many addresses does IPv6 give us?
3.4 x 10^38
What is 6to4 Tunneling?
6to4 Tunneling is a useful migration strategy for carrying IPv6 data over a network that's still IPv4. It's possible that you'll have IPv6 subnets or other portions of your network that are all IPv6, and those networks will have to communicate with each other. When you consider that you may find this happening over a WAN or some other network that you don't control, it could be difficult. So you have to create a tunnel by snatching the IPv6 packet that's traveling across the network and sticking an IPv4 header onto the front of it.
What is 6to4?
6to4 is the transition system, or structure that allows IPv6 packets to be transmitted over an IPv4 network without the need to configure explicit tunnels.
How is EIGRPv6 different from EIGRP?
Basically they're the same, only that they are configured a little differently.
What is Dual-Stacking?
Dual-Stacking is the most common type of migration strategy because it's easiest, and it allows our devices and applications on the network one at a time. As more and more hosts and devices on the network are upgraded, more of your communication will happen over IPv6, and then a network engineer can remove all the old IPv4 protocol stacks that are no longer needed. To configure dual-stacking, all you have to do is enable IPv6 forwarding and apply an address to the interfaces already configured with IPv4.
What is ICMPv6?
IPv4 used ICMP for many things, such as error messages like destination unreachable, and troubleshooting functions like Ping and Traceroute. ICMPv6 does the same, but it isn't implemented as a separate layer 4 protocol. It's an integrated part of IPv6 and is carried after the basic IPv6 header information as an extension header. Another cool feature... it prevents IPv6 from doing any fragmentation through an ICMPv6 process called path MTU discovery.
How is OSPFv3 (IPv6 version) different from OSPFv2 (IPv4)?
In OSPFv2, the router ID (RID) is determined by the highest IP addresses assigned to the router. In version 3, you assign the RID, area ID, and link-state ID, which are all still 32-bit values but are not found using the IP address anymore because an IPv6 address is 128 bits.
What is an Anycast Address?
Like Multicast Addresses, an Anycast address identifies multiple interfaces, but there's a big difference: the anycast packet is only delivered to one address... actually to the first one it finds defined in terms of routing distance. You can apply a single address to more than one interface. You could call them one-to-one-of-many addresses.
What is a Link-Local Address?
Link-Local Addresses are like the private addresses in IPv4 in that they're not meant to be routed. They are a tool that gives you the ability to throw a temporary LAN together for meetings or for creating a small LAN that's not going to be routed but still needs to share and access files and services locally.
What is NAT-PT?
NAT-PT is a last-resort migration strategy. With it, your IPv4 hosts can only communicate with other IPv4 hosts, and those that are native IPv6, with other IPv6 hosts. Unlike 6to4 tunneling, with NAT-PT there is no encapsulation. The data of the source packet is removed from one IP type and repackaged as the new destination IP type. You can use static NAT-PT (one IPv4 address to one IPv6 address), dynamic (using a pool), and NAPT-PT (Network Address Port Translation) (using a port number).
Does IPv6 allow one address for each host and network?
No, it allows multiple addresses for each, which can increase the network availability factor for a business.
What is a Unicast Address?
Packets addressed to a Unicast address are delivered to a single interface. For load balancing, multiple interfaces can use the same address.
How does the additional address room from IPv6 improve efficiency?
The additional address room permits more levels of hierarchy and a more flexible address architecture. This makes routing much more efficient and scalable because the addresses can be aggregated a lot more effectively.
How does the new IPv6 header improve efficiency?
The header in an IPv6 packet has half the fields, and they are aligned to 64 bits, which can really increase processing. Compared to IPv4, lookups happen at light speed.
What is RIPng?
The primary features of RIPng are the same as RIPv2. It is still a distance-vector protocol, has a max hop count of 15, and uses split horizon, poison reverse and other loop avoidance mechanisms, but it now uses port 521. It still uses multicast to send its updates, but in IPv6, it uses FF02::9 for the transport address. The difference with RIPv2 is that with RIPng, the router keeps track of the next-hop address using the link-local address, not a global address. Also, to configure, you need to be in interface config mode, not router config mode.
What is stateless autoconfiguration?
The type of autoconfiguration where a host doesn't contact or connect and receive any further information from the router after the autoconfiguration.
How are broadcasts used in IPv6?
There is so nuch thing as a broadcast in IPv6 because it uses multicast traffic instead.
What is a Unique Local Address?
Unique Local Addresses are also intended for non-routing purposes, but they are nearly globally unique, so it's unlikely you'll ever have one of them overlap. They were designed to replace site-local addresses, so they basically do almost exactly what IPv4 private addresses do... allow communication throughout a site while being routable to multiple networks.
Why do we need IPv6?
We need to communicate and our current system isn't cutting it anymore. We are running out of addresses and we need more flexibility, efficiency, capability, and optimized functionality for our ever-increasing network needs.
