HP-UX C SIP Stack Programmer's Guide (Novembery 2007)

Working with the Transport Layer 325
Working with IPv6 Addresses
pritf("Connection 0x%x: remote multihoming address %s was %s", hConn,
pAddrInfo->address.strIP,
}
break;
default:
printf("Connection 0x%x: status %d was reported", hConn, eStatus);
}
return;
}
/*===============================================================*/
In some standards, the primary address is referred to as a path. Paths can be
changed by peers at any moment after the connection was established.
WORKING WITH
IPV6 ADDRESSES
IPv6 (Internet Protocol Version 6) is the "next generation" protocol designed by
the IETF to replace the current internet protocol, IPv4. IPv6 overcomes a
number of problems in IPv4, such as the limited number of available IPv4
addresses. It also adds many improvements to IPv4 in areas such as routing and
network auto-configuration. IPv6 is expected to gradually replace IPv4, with the
two coexisting for a number of years during a transition period.
The most significant change is that IPv6 supports an address scheme that uses
128 bit address space compared with the 32 bit IPv4 address. The SIP Stack
enables an application to work with the IPv4 IP Stack, IPv6 IP Stack or dual
stacks. Supporting the IPv6 scheme affects the low-level services needed from
the operating system as well as message and headers syntax. It does not affect
the way SIP works with transaction call-legs or other objects.
IPV6 ADDRESS
S
YNTAX
In IPv6 addresses there are eight groups of four digits each. The hexadecimal
number system is used for the digits. Thus, each group occupies 16 bits of space
and the entire address represents (but does not always require) 128 bits.
For example, 3ffe:6a88:85a3:08d3:1319:8a2e:0370:7344. is a valid address. If a
4 digit group is 0000, it may be omitted, thus in the syntax of IPv6,
3ffe:6a88:85a3:0000:1319:8a2e:0370:7344 is the same as
3ffe:6a88:85a3::1319:8a2e:0370:7344.
Following this rule, if more than two consecutive colons result from this
omission, they may be reduced to two colons, as long as there is only one group
of more than two consecutive colons. Thus, all the following addresses are valid
and have the same meaning,
 2001:2353:0000:0000:0000:0000:1428:57ab