Internet Protocol Conventions for IPv4 and IPv6

The DS8000 supports the use of Internet Protocol Version 4 (IPv4) and Internet Protocol Version 6 (IPv6). Customer network ports can be configured using the hardware management console (HMC) to use either or both standards. IPv6 provides a higher level of security than IPv4.

An IPv4 address is 32 bits. An IP Address is shown as 4 decimal numbers representing 4 bytes: d.d.d.d where d = decimal number (0 - 255). High order bits are the network identifier and lower order bits are the host identifier. The number of bits in a network identifier is defined by a subnet mask which looks like an IP address with all 1s in high order bits and all 0s in low order bits (for example, 255.255.255.0). An IP address with the host identifier set to all 1s is a broadcast address for all hosts on the network. An IP address can also include a port number. The port number follows the IP address and is separated by a colon (for example, 250.250.250.1:8451).

An IPv6 address is 128 bits. The preferred IP address format has 8 hexadecimal numbers representing 16 bytes (for example, x:x:x:x:x:x:x:x (x = X‘0' - X‘FFFF')). An IPv6 address can contain an embedded IPv4 address. The format has 6 hexadecimal and 4 decimal numbers representing 16 bytes (for example, x:x:x:x:x:x:d.d.d.d (x = ‘0'x - X‘FFFF' and d = 0 - 255)). A compressed form allows one string of 0s to be replaced by ‘::' (for example, FF01:0:0:0:0:0:0:1A2 can be represented by FF01::1A2). High order bits are for the subnet prefix. Lower order bits are for the interface identifier.

An IPv6 address can have a number of bits in a subnet prefix that are defined by a decimal prefix following the IP address (for example, FF01::101/96 has a 96–bit subnet prefix and a 32–bit interface identifier). Most IPv6 address are required to have a 64–bit prefix length. Specific high order bit combinations in the subnet prefix are defined for specific purposes. An IPv6 IP address can also specify an IP port number (for example, [x:x:x:x:x:x:x:x]:p, where p = decimal number).

Multiple IPV6 addresses can be assigned to an interface:
Link-local address
Assigned on a given subnet, only one is one required. The first 10 bits of Link local addresses are limited to B‘1111 1110 10' (for example, FE80::1)
Global uni-cast address
Used for cross subnet identification. Any prefix other than 1s is reserved for a Link-local address.
Multicast, unspecified, or loop back 0 - N any-cast addresses
Used to deliver a message to all interfaces with that multicast address. The first 8 bits of a multicast address is limited to B'1111 1111' (for example, FF01::1).
Transient addresses
Addresses that can also be dynamically assigned for special purposes.
Special addresses
Unspecified address
Indicates the absence of an address.
Loop back address
The loop back address is ::1 (the host sends a message to itself).
Embedded IPv4 addresses
Addresses are limited to ::FFFF:d.d.d.d
No broadcast addresses
Addresses that do not have the host identifier set to all 1s.