IPv6 - 128 bit
enhancement: ICMPv6, includes address resolution and address auto-configuration
NAT technology is problematic:
- for many applications.
- creates latency
- has limitations that severely impede peer-to-peer communications.
There are three broad categories of IPv6 addresses:
1. Unicast
2. Multicast
3. Anycast
The prefix length is used in IPv6, unlike slash notation.
example:
Strongly recommended using 64-bit interface id for most networks, because SLAAC uses 64bits for the interface-id as well as makes subnetting easier to create and manage.
IPv6 Unicast address types:
1. Global unicast - use GUA (Global unicast Address) for routing globally and reach the remote network host.
2. link-local - use fe80::/10 - febf::/10 type address to send a packet to the any destination in its own network.
3. loopback::1 - a special type of address, which is used to check its own functions of a host.
4. Unique Local - fc00::/7 - fdff::/7
5. embedded ipv4
6. unspecified address
Link-local address (LLA):
Every ipv6-enabled network interface must an LLA. Ipv6-enabled host creates an IPv6 LLA even if the device hasnot been assigned a GUA. LLA has a specified range of fe80::/10 - febf::/10. There are two ways the device can obtain an LA.
1. Statically.
2. Dynamically
-> By using randomly generated values.
-> extended unique identifier (EUI) method which uses MAC address along with additional bits.
Note: Best practice is to set the default gateway address equal to Router's LLA. Though the Router's GUA will work fine.
Ipv6 Global unicast address (GUA):
001 or 2000::/3 is fixed for GUA. So it begins with 2 or 3 e.g. 2000::/3 - 3fff::/3. As a result, 1/8th if the total available ipv6 address space is being used worldwide.
Note: 2001:db8::/32 address has been reserved for documentation purposes as well as used in examples.
global routing prefix - 48 bits
subnet id - 16 bits
interface-id - 64 bits
Note: GUA is not a requirement for a host for being active in its own network. Only LLA needs for
There are two ways in which a device can obtain an IPv6 GUA.
1. Statically
2. Dynamically
-> Stateless
-> SLAAC only
-> SLAAC with DHCPv6 server (Stateless DHCPv6)
-> Stateful
-> DHCPv6 server (Stateful DHCPv6)
SLAAC only:
The router sends a Router Advertisation message with Some information every 200 seconds:
- Network prefix
- prefix-length
- default gateway, the LLA for router
- DNS server
- MTU
Use the EUI-64 process or randomly generated 64 bit for interface id. A host can also send a Router Solicitation (RS) message requesting that an IPv6-enabled router send the host an RA.
Note: There is no further information available from a DHCPv6 server.
Stateless DHCPv6:
The router sends Router Advertisation message with:
- Network prefix
- prefix-length
- default gateway, the LLA for router
stateless DHCPv6 provides:
- DNS server address
- Domain name
similarly, EUI-64 or randomly generated process can be used for interface id.
EUI-64 - The host creates an interface ID using its 48-bit MAC address. The host inserts the hex value of fffe in the middle of the address and flips the seventh bit of the interface ID. This changes the value of the second hexadecimal digit of the interface ID. Some operating systems default to the randomly generated interface ID instead of the EUI-64 method, due to privacy concerns. This is because the Ethernet MAC address of the host is used by EUI-64 to create the interface ID.
Stateful DHCPv6:
The router sends a Router Advertisation message with:
-default gateway, the LLA for router
DHCPv6 provides:
- GUA
- DNS server address
- Domain name
Note: Serial interface doesn't have an ethernet MAC address.
Multicast address: have fix prefix bit ff00::/8. this address can only be used as a destination address and not for the source address.
there are two types of IPv6 multicast addresses:
- Well-known multicast addresses.
--> ff02::1 means all node
--> ff02::2 means all router
- Solicited node multicast address
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