Internet Protocol v6
what are the multicast scopes for IPv6?
0 reserved 1 Interface-Local scope 2 Link-Local scope 3 reserved 4 Admin-Local scope 5 Site-Local scope 6 (unassigned) 7 (unassigned) 8 Organization-Local scope 9 (unassigned) A (unassigned) B (unassigned) C (unassigned) D (unassigned) E Global scope F reserved The same way we have common reserved multicast groups in IPv4 e.g. 224.0.0.1 and 224.0.0.2, we also have reserved multicast groups in IPv6 with an addition of "scope". For example, FF01::1 identifies the group of IPv6 nodes within the interface-local scope. Hint: FF01 = 1111111100000001; therefore the scop field has a value of 0001, which represents the interface-local scope from our list of values above. Consequently, FF02::1 identifies the group of IPv6 nodes within the link-local scope.
Another set of recommendation when shortening an ipv6 address?
1. Leading zeroes MUST be suppressed. 2. You MUST use the "::" to its maximum capacity. 3. The "::" MUST NOT be used to represent just one 16-bit 0 field. This RFC, however, recommends using the double colon for "two or more groups of 16 bits of zeroes." 4. If you have multiple groups of 16-bit zeroes that can be replaced by "::", you MUST use the "::" in place of the longest group. 5. Finally, you MUST use all lowercase.
how can you shorten an IPv6 address?
1. Leading zeroes in an individual field (a field of 4 hexadecimal characters) can be left out. Trailing zeroes cannot be omitted. 2. You can indicate one or more groups of 16 bits of zeroes using a double colon, i.e., "::" However, the double colon can only be used once in any single IPv6 address.
how many bits does an IPv6 address have?
128 bits.
how do you represent an IPv6 address?
32 Hexadecimals numbers, organized into 8 quartets of 4 Hex digits separated by a colon, to represent a 128-bit Ipv6 Address example - 2001:0db8:85a3:0000:0000:8a2e:0370:7334
What is an Inverse Neighbor Discovery?
A router begins with the knowledge of the neighbors link layer address and instead needs to dynamically learned the IPv6 address used y that neighbor. IPv6 solves the problem on LAN using ND, and now for frame relay it uses Inverse neighbor Discovery (IND) Which is also a part of ICMPv6 Protocol suite IND currently is not supported in Cisco IOS, so if ever you have an IPv6 frame relay, a static mapping will be needed to avoid connectivity issues.
how does a stateless auto config works?
Allows a host to automatically learn the key pieces of addressing information - prefix, host, and prefix length - plus the default router IP address and DNS IP Addresses. Step 1. IPv6 Neighbor Discovery Protocol (NDP) - uses Router solicitation and Router advertisement messages to learn The prefix, prefix length and default router. Step 2. EUI-64 ( Extended Unique Identifier - 64) to derive the interface id of the ipv6 address Step 3. Stateless DHCP to learn the DNS IPv6 Address
what is a site-local IPv6 address?
As mentioned before, site-local unicast addresses are deprecated and new implementations should not support these addresses; however, existing implementations may continue to use site-local IPv6 unicast addresses. Site-local IPv6 unicast addresses are equivalent to the private IPv4 addresses, i.e., 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. There were designed to be used within a site (e.g., an organization) without needing a global prefix (i.e., not routable on the Internet). The format for site-local unicast addresses is similar to link-local unicast addresses, except that site-local unicast addresses begin with bits 1111111011 i.e. fec0::/10 10 bits ( 1111111011 ) + 54 bits (subnet id) = network id 64 bits = interface id
What port does DHCPv6 clients, servers and agents listen to?
Clients listen to UDP 546 and the servers, relay agent listen to UDP 547
what is a global unicast address?
Every other unicast IPv6 address is a global unicast address, except those that fall under special uses. Global unicast addresses are equivalent to public IP addresses in IPv4. Currently, IANA is delegating global unicast addresses under the 2000::/3 prefix. 3 bits (001) + 45 bits ( global routing prefix) + 16 bits ( subnet id ) = Network ID 64 bits = Interface ID 0010 0000 0000 0000 :: /3 meaning the first 3 bits must be 001 The range of this will be 2000 - 3000 ::/3
what is an EUI-64?
Extended Unique Identifier (EUI), as per RFC2373, allows a host to assign iteslf a unique 64-Bit IP Version 6 interface identifier (EUI-64). This feature is a key benefit over IPv4 as it eliminates the need of manual configuration or DHCP as in the world of IPv4. The IPv6 EUI-64 format address is obtained through the 48-bit MAC address. The Mac address is first separated into two 24-bits, with one being OUI (Organizationally Unique Identifier) and the other being NIC specific. The 16-bit 0xFFFE is then inserted between these two 24-bits to for the 64-bit EUI address. IEEE has chosen FFFE as a reserved value which can only appear in EUI-64 generated from the an EUI-48 MAC address. Next, the seventh bit from the left, or the universal/local (U/L) bit, needs to be inverted.
what is the multicast address reserve for IPv6 host to send for unknown DHCP?
FF02::1:2
what multicast address does RA and RS uses?
FF02::2 RS FF02::1 RA
What does NDP use for Layer 2 mapping resolution?
Host A sends Neighbor Solicitation (NS) ICMP message (multicast) asking for Host B MAC address, this is sent to the solicited node multicast address Then Host B will reply in Neighbor Advertisement (NA) back to Host A, this is unicast. Then, Host A can already encapsulate data packets to Host
Organizations that is handling the IPv4 and Ipv6 address assignment?
ICANN - Internet Corporation for Assigned Network Numbers - handles IPv6 Address assignment, owns the process. IANA - Internet Assigned Numbers Authority - manages the process. RIR - Regional Internet Registries - Asia Pac, North America, Central / South America Europe and Africa
what is a solicited-node multicast address?
If you would notice the destination Solicited-node multicast address, this address represents all hosts with the same last 24 bits of their IPv6 address. By sending the packets to the solicited node multicast address, the packet reach the correct host, and other few hosts. The solicited node multicast address begins with FF02::1:FF00/104, the last 24 bits will be formed by adding the last 24 bits of the Ipv6 address (6 hex) Host B IPv6 Address : 2340:1111:AAAA:1:213:19FF:FE7B:5004 Host B Solicited node multicast address : FF02::1:FF7B:5004
what is an IPv6 multicast address?
Multicast is also familiar from IPv4 and is used for one-to-many communication. A multicast IPv6 address identifies a group of interfaces (typically interfaces on different nodes). IPv6 multicast addresses begin with bits 11111111 i.e. ff00::/8
what is a Neighbor Discovery Protocol?
NDP has many function, one of this function is to allow host to send multicast on all routers asking for them to announce two key pieces of information - IPv6 addresses of routers willing to act as default gateway and the all known Ipv6 prefix on the link. It uses Router Solicitation Message and Router Advertisement for SLAAC. For Layer 2 resolution, NDP uses NS Neighbor Solicitation and NA Neighbor advertisement.
how do you configure a static link local address on an interface?
R1(config-if)#ipv6 address FE80::1 link-local
what is a link-local IPv6 address?
Remember the 169.254.0.0/16 in IPv4? The link-local IPv6 unicast addresses are the equivalent of those addresses. These link-local addresses begin with the bits 1111111010 i.e. fe80::/10 the range of FE8,FE9,FEA or FEB. Link-local addresses are used for communication on a single link, i.e., communication between neighboring nodes for automatic address configuration, neighbor discovery, and so on. 10 bits (1111111010) + ( all 0's ) 54 bits = network id 64 bits = interface id • Used as the source address for RS and RA messages for router discovery (see NDP on autoconfiguration) • Used by neighbor discovery (eq. of ARP in Ipv4)( Neighbor Solicitation and Advertisement ) • As the next-hop IPv6 address for IP routes
what's the difference between stateful and stateless dhcp?
Stateful - does track state information about each client, such as the IP address leased to that client and the length of time for which the lease is valid. Stateless - does not track any state information.
what are the four methods you can assign a global unicast address?
Stateful DHCP Stateless configuration Static configuration Static configuration with EUI-64
what is an IPv6 loopback address?
The loopback address is used for "self" communication, and due to its usefulness, it also finds application in IPv6. The IPv6 loopback address is represented as 0:0:0:0:0:0:0:1 or simply ::1/128.
what is ipv6 duplicate address detection?
The purpose of this check is to prevent hosts from creating problems by trying to use the same IPv6 address That is already being used by another host on the link. (when a router or host first learn an IPv6 address or beginning to work from being shut down) The process would be the host would be sending the same neighbor solicitation message, only with the difference of that it will put its own solicited node multicast address, this way if any host replies with an answer of the same ipv6 address it would know that someone is already using it.
what is an IPv6 anycast address?
This is something we are not familiar with from IPv4. Anycast IPv6 addresses are actually unicast IPv6 addresses that are assigned to more than one interface (typically interfaces on different nodes). Traffic destined to an anycast address is delivered to the NEAREST interface having that address - nearest as seen by the routing protocol. Anycast IPv6 addresses are from the same address space as unicast IPv6 addresses; as such, these addresses are not distinguishable from unicast addresses. Therefore, an anycast address is a unicast address that has been assigned to more than one interface.
what is an IPv6 unicast address?
Unicast IPv6 addresses identify a single interface within the scope of that unicast address. there are different types of unicast address like link local, site local, unique local, global unicast address.
what is a unique local IPv6 address?
Unique local IPv6 unicast addresses defined in RFC 4193 are used for similar purposes with site-local, which is to provide globally unique (to a high probability) IPv6 unicast addresses for local communication, i.e., not routable on the Internet. All unique local IPv6 unicast addresses have a fixed value of 1111110 in the prefix field, i.e., fc00::/7. What makes these addresses "unique" is the way the "Global ID" is generated—by using a pseudo-random algorithm; 7 bits (1111110) + 1 bit (1) + 40bits ( global id ) + 16 bits (subnet id) = network id 64 bits = interface id FD (FD00::/8)
What are the IPv6 several address types?
Unspecified, loopback, unicast, multicast and anycast. that's right! no broadcast!
what do you call the text representation of IPv6 address?
colon hexadecimal
how can you enable IPv6 on an interface?
either by assigning an IPv6 address to the interface (using the ipv6 address command) or by issuing the ipv6 enable interface configuration command
how will you enable IPv6 routing?
ipv6 unicast-routing note :Before IPv6 routing is enabled on routers, they will only send neighbor advertisement and neighbor solicitation messages. However, once IPv6 routing is enabled on routers, they begin sending router advertisement messages and also respond to router solicitation messages.
what command gives you more IPv6 details about a particular interface?
show ipv6 interface <interface_name>
what command gives you a brief details about the interfaces where IPv6 in enable?
show ipv6 interface brief
what command can show the neighbor cache of the router?
show ipv6 neighbors Ipv6 uses an ipv6 neighbor table, to keep track of the neighbors layer 3 to layer 2 address.
what command is use to show the IPv6 routing table?
show ipv6 route
If you have set a static link local, how does it affect to next EUI-64?
the convertion of EUI-64 will be based on the one what you statically assigned, not the normal mac address conversion
what is an IPv6 unspecified address?
this address is consists of all 0's, This address cannot be assigned to a node nor can it be used as the destination address of IPv6 packets. An example of the use of this address is in the source address field of IPv6 packets sent by a newly initializing host that does not have an IPv6 address yet. ( ::/128 )
in SLAAC how does a host learn its DNS?
thru a stateless DHCP ( of course it would also work with stateful)
what are the features of IPv6 address?
• Address assignment features - DHCP and Stateless Autoconfiguration • Built in support for address renumbering • Built in support for mobility • Provider independent and dependent public address space • Aggregation • No need for NAT/PAT • IPSec • Header Improvements • No Broadcast • Transition tools
