Unit 4 IPv6 Addressing
Loopback address
(0:0:0:0:0:0:0:1) - within a reserved address block, is used for testing (for the host to send a packet to itself). This is often expressed as ::1
wastage
32 bits can express 2^32 unique addresses (in excess of four billion). However, the way in which addresses have been allocated has been inefficient, leading to _____ if available addresses.
ff02::1:2
All link-local DHCP agents.
ff02::2
All link-local routers
octal
An ___ number is base 8. With these, the digits 8 and 9 are unused. Any value above 8 is shifted one position to the left. For example, the value 255 in decimal is 377 in this form (3x8x8)+(7x8)+7
broadcast
As IPv6 does not support _____, clients use the multicast address ff:02::1:2 to discover a DHCP server.
interface
As a MAC address is currently 48 bits (6 bytes), a (relatively) simple translation mechanism allows driver software to create a 64-bit ___ ID (an EUI-64) from these 48 bits.
unicast address
As with IPv4, a ____ identifies a single network interface.
digit
Base 10 means that each ___ can have one of ten possible values (0...9)
two
Binary is base 2 so a digit in any given position can only have one of ___ values each place position is the next power of 2.
supplemental
DHCPv6 servers can be used to assign _____ information such as DNS configuration and default gateway to clients
546, 547
DHCPv6 uses ports ___ (clients) and ___ (servers) rather than 67 and 68 as with DHCPv4.
Private Network Migration Strategies
Dual-stack hosts can run both IPv4 and IPv6 simultaneously and communicate with devices configured with either type of address.
IPv4 mapped addresses
Dual-stack hosts may also make use of _____. This kind of address is expressed ::ffff:192.168.0.1 (that is, 80 zeroes followed by 16 ones and then the 32-bit IPv4 address. expressed by convention in dotted decimal)
binary digits
Each hex digit lines up neatly with four ____, so conversion is a straightforward matter of dividing the _____ into groups of four, then converting each group individually.
RFC 4291 definition of MAC-derived address (interface identifier)
Essentially, the digits fffe are added in the middle of the address and the U/L bit is flipped. (first two digits)
IPv4 packets
Essentially, when 6to4 is implemented, the IPv6 packets are inserted into _____ and routed over the IPv4 network to their destination.
Options
Extension headers of IPv6 replace the ___ field in IPv4
Informational messaging
ICMPv6 supports ICMPv4 functions such as echo and redirect plus a whole new class of messages designed to support ND and MLD (such as router and neighbor advertisements and solicitations)
16
IPv6 addresses comprise eight __-bit numbers (double-byte or double-octet) with each double-byte number expressed as 4 hex digits.
fe80::5efe.w.x.y.z
ISATAP hosts use the link-local range _______, where w.x.y.z is a dotted decimal IPv4 address.
network
If the prefix is /48, then if the first 48 bits of an IPv6 address were the same as another address, the two would belong to the same ____.
format
In DHCPv6, the ____ of messages is different but the process of DHCP server discovery and address leasing is fundamentally the same.
interface, network
In IPv6, the ___ identifier is always the last 64 bits; the first 64 bits are used for ___ addressing.
32
In Pv4 the addressing scheme is based on a __ -bit binary number.
ARP
In Pv4, IP address resolution to a specific hardware interface is performed using ____. ___ is "chatty" and requires every node to process its messages, whether they are relevant to the node or not.
6to4
In ___ automatic tunneling (RFC 3056), no host configuration is necessary to enable the tunnel. These addresses start with a leading 2002.
Hexadecimal notation
Is a convenient way of referring to the long sequences of bytes used in IPv6. This is base 16 with the possible values of each digit represented by the numerals 0...9 and the characters A, B, C, D, E, F.
anycast
Like IPv4, IPv6 defines a number of addressing schemes. The are unicast, multicast, and ____.
fe80, interface ID
Link-local addresses start with a leading ___ while the next 54 bits are set to zero and the last 64 bits are the ______
stop-gap
Network Address Translation (NAT) and private addressing have provided a "____" solution to the problem of supply exhaustion (IPv4 addressing)
neighbors
Nodes on the same link are referred to as _____.
computer networking
Octals are not widely used in ______ as there is far too much scope for confusing them with decimal values but many values in computing are represented in octets (or bytes).
Internet Tunneling Migration Strategies
Secondly, tunneling can be used to deliver Ipv6 packets across the IPv4 internet.
stateful
Some networks may prefer to deploy ____ configuration rather than using SLAAC.
Reserved Address
The 0000::/8 block (that is, IPv6 addresses where the first bits are 0000 0000) is reserved for special functions.
IPv6 packet
The ____ consists of two or three elements: the main header, one or more optional extension headers, and the payload.
RFC 4941 definition of temporary interface ID or token
The client device uses a psuedo-random number for the interface ID. There is some concern that using interface identifiers would allow a particular host to be identified and closely monitored when connecting to the internet and using a token mitigates this to some degree.
APIPA
The equivalent in IPv4 to Link-local addressing is ____ and its 169.254.0.0 addresses. However, unlike IPv4, an IPv6 host is ALWAYS configured with link-local addresses (one for each link), even if it also has a globally unique address.
Interface ID / EUI-64
The interface can be determined using two techniques. One is by using the client computer's network interface MAC address. The second technique, the client device uses a pseudo-random number for the interface ID.
Miredo
The open source alternative of Teredo, available for UNIX / Linux Operating systems
anycast addressing
The packet is sent to the member of the group physically closest to the transmitting host. This is principally used for routing protocol traffic
bandwidth. multicast
There is no concept of broadcast addressing in IPv6. Eliminating the use of broadcasts saves network ____. Functions that would have used broadcasts in IPv4 use special _____ addresses in IPv6.
anycast address
This identifies multiple addresses. Is used where a message must be sent to any member of a group but not necessarily to all of them.
IPv4 mapped addresses
This kind of address is never ASSIGNED to hosts but used by IPv4/IPv6 routers to forward traffic between IPv4 and IPv6 networks.
Multicast Listener Discovery (MLD)
This protocol performs some of the same functions for IPv6 as IGMP does for IPv4. It is defined in RFC 3810
base
To start with the familiar; decimal numbering can also be referred to as ___ 10.
4to6
Transferring IPv4 through an IPv6 network
ISATAP (Intra-Site Automatic Tunnel Addressing Protocol)
Under ______ a dual-stack router takes an IPv6 packet and rewrites it as an IPv4 packet. The ____ router allows for a network with mixed IPv4 and IPv6 hosts but cannot be used for routing BETWEEN networks.
Stateless Address Autoconfiguration
Unlike IPv4, IPv6 addresses do not need to be assigned from a server, such as a DHCP server, and instead rely on a mechanism known as ______. This process is fully described in RFC 4862.
multicast
Unlike IPv4, IPv6 routers MUST support ___.
ICMPv6
Updated version of ICMP used in IPv6
Neighbor Discovery (ND)
Used in IPv6. Each unicast address for an interface is configured with a corresponding solicited-node multicast address.
UDP
Using ____ rather than TCP allows tunneling through NAT devices.
URI (web address)
Where IPv6 addresses are used as part of a ___, as both formats use colon delimiters to mean different things, the IPv6 address must be contained within square brackets.
dual-stack
Windows XP / Vista / 7 and Windows Server plus current versions of UNIX/Linux implement ____ IP.
network prefix
Within 64-bit network ID, as with CIDR, the length of any given ____ is used to determine whether two addresses belong to the same network.
Unspecified address
Within a reserved address block, is a host that has not obtained a valid address. Often expressed as :: (0:0:0:0:0:0:0:0)
Teredo
____ tunnels IPv6 packets as Ipv4-based UDP messages over port 3544.
Link-local addressing
addresses in this addressing are used by IPv6 for network housekeeping traffic. The addresses also span a single subnet (they are not forwarded by routers)
Local address resolution
allows a host to discover other nodes and routers on the local network (neighbors)
Prefix discovery
enables a host to discover the known network prefixes that have been allocated to the local segment. This also allows next-hop determination (whether a packet should be addressed to a local host or router)
multicast address
identifies multiple network interfaces.
scope
is a region of the network
IPv6 (also called IP Next Generation of IPng)
provides a long-term solution of address space exhaustion. Its 128-bit addressing scheme has space for 340 undecillion unique addresses.
broadcast
these addresses are not implemented in IPv6. Instead of these kinds of addresses, hosts use an appropriate multicast address for a given situation. (IPv6)
public
6to4 supports only ____ IPv4 addresses (that is, those NOT behind a NAT device)
translate
A dual-stack router can ____ between IPv6 and IPv4.
zone ID
A given host may have links to a loopback address, Ethernet, and a VPN. Each of these links may use the same link-local address, so each is assigned a ___ to make it unique. Zone indices are generated by the host system, so where two hosts communicate, they may be referring to the link using different zone IDs.
zone index
A link-local address is also appended with a ____ (or scope_id) of the form %1 (Windows) or %eth0 (Linux). This is used to define the source of the address and make it unique to a particular link.
ff02::1
All link-local nodes
Error messaging
ICMPv6 supports the same sort of destination unreachable and time exceeded messaging as ICMPv4. One change is to introduce a Packet Too Big class of error. (Under IPv6, routers are no longer responsible for packet fragmentation and reassembly so the host must ensure that they fit in the MTUs of the various links used.)
Neighbor Discovery
The ____ protocol performs some of the functions on an IPv6 network that ARP and ICMP perform under IPv4. It is defined in RFC 4861.
ff02::1:ff
The corresponding solicited-node multicast address (ND) comprises the prefix _____ plus the last 24 bits of the unicast address.
255
The number ___ can be written out as (2x10x10) + (5x10) + 5 in decimal numbering.
address resolution
The solicited-node address is used by ND to perform _______.
DHCPv6
can serve the same sort of purpose as for DHCP under IPv4. Is defined in RFC 3315/
Address Autoconfiguration
enables a host to configure IPv6 addresses for its interfaces automatically and detect whether an address is already in use on the local network.
Redirection
enables a router to inform a host of a better route to a particular destination
addressing
IPv6 unicast ___ is scoped
Global
These scopes provide the equivalent of public addressing schemes in IPv4 while link-local schemes provide private addressing.
