topic 10 : ipv6 addressing Flashcards
why do we need ipv6?
- ipv4 is running out of addresses, ipv6 has a much larger 128-bit address space
- development of ipv6 also included fixes for ipv4 limitations and other enhancements
- increasing internet population
- limited ipv4 address space
- issues with NAT and IoT
tools/protocols for migrating networks to ipv6
1) dual stack : device runs on both ipv4 and ipv6 protocol stacks simultaneously
2) tunneling : method of transporting an ipv6 packet over an ipv4 network. the ipv6 packet is encapsulated inside an ipv4 packet
3) translation : NAT64 allows ipv6-enabled devices to communicate with ipv4-enabled devices using a translation technique similar to NAT for ipv4
ipv6 addressing formats
- 128-bit length, written in hexadecimal
- not case-sensitive, can be written in lowercase/uppercase
- preferred format of writing : x:x:x:x:x:x:x:x, each ‘x’ consists of 4 hexadecimal values
rule 1 to reduce ipv6 address notation
- omit any LEADING 0s
eg : 01ab = 1ab
rule 2 to reduce ipv6 address notation
- double colon (::) can replace any single, contiguous string of one or more 16-bit hextet consisting of all zeros
3 categories of ipv6 addresses
1) unicast : interface on an ipv6-enabled device
2) multicast : used to send a single ipv6 packet to multiple destinations
3) anycast : This is any IPv6 unicast address that can be assigned to multiple devices. A packet sent to an anycast address is routed to the nearest device having that
address.
ipv6 unicast addresses
unicast : interface on an ipv6-enabled device
a packet sent is received by the interface that is assigned to that address
ipv6 multicast addresses
multicast : used to send a single ipv6 packet to multiple destinations
- one to many or controlled broadcast
- identifies a group of interfaces
- reserved address range starting FF00::0/8
- host to group of hosts
ipv6 anycast addressing
anycast : This is any IPv6 unicast address that can be assigned to multiple devices. A packet sent to an anycast address is routed to the nearest device having that
address.
- one to one, the nearest node will respond
- an unicast address that is configured at interfaces on different nodes
ipv6 prefix length
- can range from 0 to 128
- recommended ipv6 prefix length for LANS (and most other types of networks) is /64
global unicast address (GUA)
- similar to a public ipv4 address
- globally unique, internet-routable addresses
link-local address (LLA)
- required for every ipv6-enabled device
- used to communicate with other devices on the same local link and only on that link
- not routable and are confined to a single link
- packets with a source or destination LLA cannot be routed
- every ipv6-enabled network interface must have an LLA
- if LLA not configured manually, the device will automatically create one
- in the fe80::/10 range
significant differences from RFC 1918 private addresses for ipv4
unique local address :
1) used for local addressing within a site or between a limited number of sites
2) used for devices that will never need access to another network
3) not globally routed or translated to a global ipv6 address
range of ipv6 unique local addresses : fc00::/7 to fdff::/7)
well-known ipv6 multicast address
- assigned and are reserved for pre-defined groups of devices
2 common multicast groups :
1) ff02::1 all-nodes multicast group
- all ipv6-enabled devices join
- packet sent here is received and processed by all ipv6 interfaces on the link or network
2) ff02::2 all-routers multicast group
- all ipv6 routers join
- router becomes a member when it is enabled as an ipv6 router with the ipv6 unicast-routing global configuration command
solicited-node ipv6 multicast
- similar to the all-nodes multicast address
- mapped to a special Ethernet multicast address
- the Ethernet NIC can filter the
frame by examining the destination
MAC address without sending it to
the IPv6 process to see if the
device is the intended target of the
IPv6 packet.
