ibm-information-center/dist/eclipse/plugins/i5OS.ic.rzai2_5.4.0.1/rzai2compipv4ipv6.xml

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<TITLE>Compare IPv4 to IPv6</TITLE>
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Description
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IPv4
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IPv6
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<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compaddress"><A NAME="rzai2compipv4ipv6__compaddress" shape="rect"></A>address</strong></TD1><TD2 valign="top" width="32.95454545454545%">32 bits long (4 bytes).  Address is composed
of a network and a host portion, which depend on address class. Various address
classes are defined: A, B, C, D, or E depending on initial few bits.  The
total number of IPv4 addresses is 4 294 967 296.  <p>The text form of the
IPv4 address is <samp class="codeph">nnn.nnn.nnn.nnn</samp>, where 0&lt;=<samp class="codeph"><var class="varname">nnn</var></samp>&lt;=255,
and each <samp class="codeph"><var class="varname">n</var></samp> is a decimal digit.  Leading
zeros can be omitted. Maximum number of print characters is 15, not counting
a mask.</p>
</TD2><TD3 valign="top" width="39.77272727272727%">128 bits long (16 bytes).   Basic architecture
is 64 bits for the network number and 64 bits for the host number.  Often,
the host portion of an IPv6 address (or part of it) will be derived from a
MAC address or other interface identifier.  <p>Depending on the subnet prefix,
IPv6 has a more complicated architecture than IPv4.</p>
<p>The number of IPv6
addresses is 10<sup>28</sup>  (79 228 162 514 264 337 593 543 950 336) times
larger than the number of IPv4 addresses. The text form of the IPv6 address
is <samp class="codeph">xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx</samp>, where each <samp class="codeph">x</samp> is
a hexadecimal digit, representing 4 bits. Leading zeros can be omitted.  The
double colon (<samp class="codeph">::</samp>) can be used once in the text form of an
address, to designate any number of 0 bits. For example, <samp class="codeph">::ffff:10.120.78.40</samp> is
an IPv4-mapped IPv6 address.  (See <span>RFC 3513</span> for details. </p>
<p>To
view this RFC, see <A HREF="http://www.rfc-editor.org/rfcsearch.html" shape="rect">RFC Editor</A> <img alt="Link outside Information Center" src="www.gif"></img> (www.rfc-editor.org/rfcsearch.html).</p>
<p> </p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compaddralloc"><A NAME="rzai2compipv4ipv6__compaddralloc" shape="rect"></A>address allocation</strong></TD1><TD2 valign="top" width="32.95454545454545%">Originally, addresses were allocated by network
class. As address space is depleted, smaller allocations using Classless Inter-Domain
Routing (CIDR) are made. Allocation has not been balanced among institutions
and nations.</TD2><TD3 valign="top" width="39.77272727272727%">Allocation is in the earliest stages. The
Internet Engineering Task Force (IETF) and Internet Architecture Board (IAB)
have recommended that essentially every organization, home, or entity be allocated
a <samp class="codeph">/48</samp> subnet prefix length. This would leave 16 bits for
the organization to do subnetting. The address space is large enough to give
every person in the world their own <samp class="codeph">/48</samp> subnet prefix length.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compaddrlife"><A NAME="rzai2compipv4ipv6__compaddrlife" shape="rect"></A>address lifetime</strong></TD1><TD2 valign="top" width="32.95454545454545%">Generally, not an applicable concept, except
for addresses assigned using DHCP.</TD2><TD3 valign="top" width="39.77272727272727%">IPv6 addresses have two lifetimes: preferred
and valid, with the preferred lifetime always &lt;= valid.  <p>After
the preferred lifetime expires, the address is not to be used as a source
IP address for new connections if an equally good preferred address is available.
After the valid lifetime expires, the address is not used (recognized) as
a valid destination IP address for incoming packets or used as a source IP
address.</p>
<p>Some IPv6 addresses have, by definition, infinite preferred
and valid lifetimes; for example link-local (see <A HREF="#rzai2compipv4ipv6__compaddrscope" shape="rect">address
scope</A>).</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compaddressmask"><A NAME="rzai2compipv4ipv6__compaddressmask" shape="rect"></A>address mask</strong></TD1><TD2 valign="top" width="32.95454545454545%">Used to designate network from host portion.</TD2><TD3 valign="top" width="39.77272727272727%">Not used (see <A HREF="#rzai2compipv4ipv6__compaddrpref" shape="rect">address
prefix</A>).</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compaddrpref"><A NAME="rzai2compipv4ipv6__compaddrpref" shape="rect"></A>address prefix</strong></TD1><TD2 valign="top" width="32.95454545454545%">Sometimes used to designate network from
host portion. Sometimes written as <samp class="codeph">/nn</samp> suffix on presentation
form of address.</TD2><TD3 valign="top" width="39.77272727272727%">Used to designate the subnet prefix of an
address. Written as <samp class="codeph">/nnn</samp> (up to 3 decimal digits, <samp class="codeph">0 &lt;=
nnn &lt;= 128</samp>) suffix after the print form.   An example is  <samp class="codeph">fe80::982:2a5c/10</samp>,
where the first 10 bits comprise the subnet prefix.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__comparp"><A NAME="rzai2compipv4ipv6__comparp" shape="rect"></A>Address Resolution Protocol (ARP)</strong></TD1><TD2 valign="top" width="32.95454545454545%">Address Resolution Protocol is used by IPv4
to find a physical address, such as the MAC or link address, associated with
an IPv4 address.</TD2><TD3 valign="top" width="39.77272727272727%">IPv6 embeds these functions within IP itself
as part of the algorithms for stateless autoconfiguration and neighbor discovery
using Internet Control Message Protocol version 6 (ICMPv6). Hence, there is
no such thing as ARP6.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compaddrscope"><A NAME="rzai2compipv4ipv6__compaddrscope" shape="rect"></A>address scope</strong></TD1><TD2 valign="top" width="32.95454545454545%">For unicast addresses, the concept does not
apply.   There are designated private address ranges and loopback.  Outside
of that, addresses are assumed to be global.</TD2><TD3 valign="top" width="39.77272727272727%"><p>In IPv6, address scope is
part of the architecture.  Unicast addresses have two defined scopes, including
link-local and global; and multicast addresses have 14 scopes. Default address
selection for both source and destination takes scope into account.</p>
<p>A
scope zone is an instance of a scope in a particular network. As a consequence,
IPv6 addresses sometimes must be entered or associated with a zone ID.  The
syntax is <samp class="codeph">%zid</samp> where <samp class="codeph">zid</samp> is a number (usually
small) or a name. The zone ID is written after the address and before the
prefix. For example, <samp class="codeph">2ba::1:2:14e:9a9b:c%3/48</samp>.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compaddrtype"><A NAME="rzai2compipv4ipv6__compaddrtype" shape="rect"></A>address types</strong></TD1><TD2 valign="top" width="32.95454545454545%">Unicast, multicast, and broadcast.</TD2><TD3 valign="top" width="39.77272727272727%">Unicast, multicast, and anycast. See <A HREF="rzai2ipv6addrtypes.htm#ipv6addrtypes" shape="rect">IPv6 address types</A> for
descriptions.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compcommtrace"><A NAME="rzai2compipv4ipv6__compcommtrace" shape="rect"></A>communications trace</strong></TD1><TD2 valign="top" width="32.95454545454545%">A tool to collect a detailed trace of TCP/IP
(and other) packets that enter and leave an iSeries server.</TD2><TD3 valign="top" width="39.77272727272727%"><p>Same for IPv6, and IPv6
is supported.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compconfig"><A NAME="rzai2compipv4ipv6__compconfig" shape="rect"></A>configuration</strong></TD1><TD2 valign="top" width="32.95454545454545%"><p>You must configure a newly installed system
before it can communicate with other systems; that is, IP addresses and routes
must be assigned.</p>
</TD2><TD3 valign="top" width="39.77272727272727%"><p>Configuration is optional,
depending on functions required. IPv6 can be used with any Ethernet adapter
and can be run over the loopback interface. IPv6 interfaces are self-configuring
using IPv6 stateless autoconfiguration. You can also manually configure the
IPv6 interface. So, the system will be able to communicate with other IPv6
systems that are local and remote, depending on the type of network and whether
an IPv6 router exists.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compdns"><A NAME="rzai2compipv4ipv6__compdns" shape="rect"></A>Domain Name System (DNS)</strong></TD1><TD2 valign="top" width="32.95454545454545%">Applications accept host names and then use
DNS to get an IP address, using socket API <samp class="codeph">gethostbyname()</samp>.
 <p>Applications also accept IP addresses and then use DNS to get host names
using <samp class="codeph">gethostbyaddr()</samp>.  </p>
<p>For IPv4, the domain for reverse
lookups is <samp class="codeph">in-addr.arpa</samp>.</p>
</TD2><TD3 valign="top" width="39.77272727272727%">Same for IPv6. Support for IPv6 exists using
AAAA (quad A) record type and reverse lookup (IP-to-name). An application
may elect to accept IPv6 addresses from DNS (or not) and then use IPv6 to
communicate (or not).  <p></p>
<p>The socket API <samp class="codeph">gethostbyname()</samp> only
supports IPv4. For IPv6, a new <samp class="codeph">getaddrinfo()</samp>  API is used
to obtain (at application choice) IPv6 only, or IPv4 and IPv6 addresses.</p>
<p>For
IPv6, the domain used for reverse lookups is  <samp class="codeph">ip6.arpa</samp>, and
if not found then ip6.int (see  API <A HREF="../apis/getnameinfo.htm" shape="rect">getnameinfo()</A>).</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compdhcp"><A NAME="rzai2compipv4ipv6__compdhcp" shape="rect"></A>Dynamic Host Configuration Protocol (DHCP)</strong></TD1><TD2 valign="top" width="32.95454545454545%"><p>Used to dynamically obtain an IP address
and other configuration information. The iSeries supports a DHCP server for IPv4.</p>
</TD2><TD3 valign="top" width="39.77272727272727%"><p>Currently, the i5/OS™ implementation
of DHCP does not support IPv6.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compftp"><A NAME="rzai2compipv4ipv6__compftp" shape="rect"></A>File Transfer Protocol (FTP)</strong></TD1><TD2 valign="top" width="32.95454545454545%">File Transfer Protocol allows you to send and receive
files across networks.</TD2><TD3 valign="top" width="39.77272727272727%">Currently, the i5/OS implementation of FTP does not support
IPv6.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compfragments"><A NAME="rzai2compipv4ipv6__compfragments" shape="rect"></A>fragments</strong></TD1><TD2 valign="top" width="32.95454545454545%">When a packet is too big for the next link
over which it is to travel, it can be fragmented by the sender (host or router).</TD2><TD3 valign="top" width="39.77272727272727%"><p>For IPv6, fragmentation
can only occur at the source node, and reassembly is only done at the destination
node. The fragmentation extension header is used.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__comphosttable"><A NAME="rzai2compipv4ipv6__comphosttable" shape="rect"></A>host table</strong></TD1><TD2 valign="top" width="32.95454545454545%">On iSeries Navigator, a configurable table
that associates an Internet address with a host name; for example, <samp class="codeph">127.0.0.1</samp>,
loopback.  This table is used by the sockets name resolver, either before
a DNS lookup or after a DNS lookup fails (determined by host name search priority).</TD2><TD3 valign="top" width="39.77272727272727%">Currently, this table does not support IPv6.
 Customers need to configure an AAAA record in a DNS for IPv6 domain resolution.
 You can run the DNS locally on the same system as the resolver, or you can
run it on a different system.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compinterface"><A NAME="rzai2compipv4ipv6__compinterface" shape="rect"></A>interface</strong></TD1><TD2 valign="top" width="32.95454545454545%">The conceptual or logical entity used by
TCP/IP to send and receive packets and always closely associated with an IPv4
address, if not named with an IPv4 address.  Sometimes referred to as a logical
interface.  <p>Can be started and stopped independently of each other and
independently of TCP/IP using STRTCPIFC and ENDTCPIFC commands and using iSeries Navigator.</p>
</TD2><TD3 valign="top" width="39.77272727272727%">Same concept as IPv4. <p>Can be started and
stopped independently of each other and independently of TCP/IP using iSeries Navigator
only.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compicmp"><A NAME="rzai2compipv4ipv6__compicmp" shape="rect"></A>Internet Control Message Protocol (ICMP)</strong></TD1><TD2 valign="top" width="32.95454545454545%">ICMP is used by IPv4 to communicate network
information.</TD2><TD3 valign="top" width="39.77272727272727%">Used similarly for IPv6; however, Internet
Control Message Protocol version 6 (ICMPv6) provides some new attributes.
 <p>Basic error types remain, such as destination unreachable, echo request
and reply. New types and codes are added to support neighbor discovery and
related functions.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compigmp"><A NAME="rzai2compipv4ipv6__compigmp" shape="rect"></A>Internet Group Management Protocol (IGMP)</strong></TD1><TD2 valign="top" width="32.95454545454545%">IGMP is used by IPv4 routers to find hosts
that want traffic for a particular multicast group, and used by IPv4 hosts
to inform IPv4 routers of existing multicast group listeners (on the host).</TD2><TD3 valign="top" width="39.77272727272727%">Replaced by MLD (multicast listener discovery)
protocol for IPv6. Does essentially what IGMP does for IPv4, but uses ICMPv6
by adding a few MLD-specific ICMPv6 type values.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compipheader"><A NAME="rzai2compipv4ipv6__compipheader" shape="rect"></A>IP header</strong></TD1><TD2 valign="top" width="32.95454545454545%">Variable length of 20-60 bytes, depending
on IP options present.</TD2><TD3 valign="top" width="39.77272727272727%">Fixed length of 40 bytes. There are no IP
header options. Generally, the IPv6 header is simpler than the IPv4 header.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compipheaderopt"><A NAME="rzai2compipv4ipv6__compipheaderopt" shape="rect"></A>IP header options</strong></TD1><TD2 valign="top" width="32.95454545454545%">Various options that might accompany an IP
header (before any transport header).</TD2><TD3 valign="top" width="39.77272727272727%">The IPv6 header has no options. Instead,
IPv6 adds additional (optional) extension headers. The extension headers are
AH and ESP (unchanged from IPv4), hop-by-hop, routing, fragment, and destination. <span>Currently,
IPv6 supports some extension headers.</span></TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compipheaderprot"><A NAME="rzai2compipv4ipv6__compipheaderprot" shape="rect"></A>IP header protocol byte</strong></TD1><TD2 valign="top" width="32.95454545454545%">The protocol code of the transport layer
or packet payload; for example, ICMP.</TD2><TD3 valign="top" width="39.77272727272727%">The type of header immediately following
the IPv6 header. Uses the same values as the IPv4 protocol field. But the
architectural effect is to allow a currently defined range of next headers,
and is easily extended. The next header will be a transport header, an extension
header, or ICMPv6.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compipheadertos"><A NAME="rzai2compipv4ipv6__compipheadertos" shape="rect"></A>IP header Type of Service (TOS)
byte</strong></TD1><TD2 valign="top" width="32.95454545454545%">Used by QoS and differentiated services to
designate a traffic class.</TD2><TD3 valign="top" width="39.77272727272727%">Designates the IPv6 traffic class, similarly
to IPv4. Uses different codes. Currently, IPv6 does not support TOS.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compinavsupp"><A NAME="rzai2compipv4ipv6__compinavsupp" shape="rect"></A>iSeries Navigator support</strong></TD1><TD2 valign="top" width="32.95454545454545%">iSeries Navigator provides a complete
configuration solution for TCP/IP.</TD2><TD3 valign="top" width="39.77272727272727%">Same for IPv6. No CL commands are available
for IPv6 configuration.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__complanconnect"><A NAME="rzai2compipv4ipv6__complanconnect" shape="rect"></A>LAN connection</strong></TD1><TD2 valign="top" width="32.95454545454545%"><p>Used by an IP interface to get to the
physical network. Many types exist; for example, token ring, and Ethernet.
Sometimes referred to as the physical interface, link, or line.</p>
</TD2><TD3 valign="top" width="39.77272727272727%"><p>IPv6 can be used with any Ethernet adapters and is
also supported over virtual Ethernet between logical partitions.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compl2tp"><A NAME="rzai2compipv4ipv6__compl2tp" shape="rect"></A>Layer 2 Tunnel Protocol (L2TP)</strong></TD1><TD2 valign="top" width="32.95454545454545%">L2TP can be thought of as virtual PPP, and
works over any supported line type.</TD2><TD3 valign="top" width="39.77272727272727%">Currently, the i5/OS implementation of L2TP does not support
IPv6.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__comploopaddr"><A NAME="rzai2compipv4ipv6__comploopaddr" shape="rect"></A>loopback address</strong></TD1><TD2 valign="top" width="32.95454545454545%">An interface with an address of <samp class="codeph">127.*.*.*</samp> (typically <samp class="codeph">127.0.0.1</samp>)
that can only be used by a node to send packets to itself.  The physical interface
(line description) is named *LOOPBACK.</TD2><TD3 valign="top" width="39.77272727272727%">The concept is the same as in IPv4. The single
loopback address is <samp class="codeph">0000:0000:0000:0000:0000:0000:0000:0001</samp> or <samp class="codeph">::1</samp> (shortened
version). The virtual physical interface is named <span>*LOOPBACK</span>.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compmtu"><A NAME="rzai2compipv4ipv6__compmtu" shape="rect"></A>Maximum Transmission Unit (MTU)</strong></TD1><TD2 valign="top" width="32.95454545454545%">Maximum transmission unit of a link is the
maximum number of bytes that a particular link type, such as Ethernet or modem,
supports. For IPv4, 576 is the typical minimum.</TD2><TD3 valign="top" width="39.77272727272727%">IPv6 has an architected lower bound on MTU
of 1280 bytes. That is, IPv6 will not fragment packets below this limit. To
send IPv6 over a link with less than 1280 MTU, the link-layer must transparently
fragment and defragment the IPv6 packets.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compnetstat"><A NAME="rzai2compipv4ipv6__compnetstat" shape="rect"></A>netstat</strong></TD1><TD2 valign="top" width="32.95454545454545%">A tool to look at status of TCP/IP connections,
interfaces, or routes.  Available using iSeries Navigator and 5250.</TD2><TD3 valign="top" width="39.77272727272727%">Same for IPv6, and IPv6 is supported for
both 5250 and iSeries Navigator.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compnat"><A NAME="rzai2compipv4ipv6__compnat" shape="rect"></A>Network Address Translation (NAT)</strong></TD1><TD2 valign="top" width="32.95454545454545%">Basic firewall functions integrated into
TCP/IP, configured using iSeries Navigator.</TD2><TD3 valign="top" width="39.77272727272727%">Currently, NAT does not support IPv6. More
generally, IPv6 does not require NAT. The expanded address space of IPv6 eliminates
the address shortage problem and enables easier renumbering.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compnetworktable"><A NAME="rzai2compipv4ipv6__compnetworktable" shape="rect"></A>network table</strong></TD1><TD2 valign="top" width="32.95454545454545%">On iSeries Navigator, a configurable table
that associates a network name with an IP address without mask. For example,
host Network14 and IP address 1.2.3.4.</TD2><TD3 valign="top" width="39.77272727272727%">Currently, no changes are made to this table
for IPv6.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compnodeinfo"><A NAME="rzai2compipv4ipv6__compnodeinfo" shape="rect"></A>node info query</strong></TD1><TD2 valign="top" width="32.95454545454545%">Does not exist.</TD2><TD3 valign="top" width="39.77272727272727%">A simple and convenient network tool that
should work like ping, except with content: an IPv6 node may query another
IPv6 node for the target's DNS name, IPv6 unicast address, or IPv4 address.
Currently, not supported.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__comppacketfilter"><A NAME="rzai2compipv4ipv6__comppacketfilter" shape="rect"></A>packet filtering</strong></TD1><TD2 valign="top" width="32.95454545454545%">Basic firewall functions integrated into TCP/IP, configured
using iSeries Navigator.</TD2><TD3 valign="top" width="39.77272727272727%"><p>You cannot use packet filtering with IPv6.</p>
 </TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__comppacketforward"><A NAME="rzai2compipv4ipv6__comppacketforward" shape="rect"></A>packet forwarding</strong></TD1><TD2 valign="top" width="32.95454545454545%">The iSeries server can be configured to forward
IP packets it receives for nonlocal IP addresses. Typically, the inbound interface
and outbound interface are connected to different LANs.</TD2><TD3 valign="top" width="39.77272727272727%"><p>IPv6 packets are not forwarded.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compping"><A NAME="rzai2compipv4ipv6__compping" shape="rect"></A>PING</strong></TD1><TD2 valign="top" width="32.95454545454545%">Basic TCP/IP tool to test  reachability. Available using iSeries Navigator
and 5250.</TD2><TD3 valign="top" width="39.77272727272727%">Same for IPv6, and IPv6 is supported, for both 5250
and iSeries Navigator.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compppp"><A NAME="rzai2compipv4ipv6__compppp" shape="rect"></A>Point-to-Point Protocol (PPP)</strong></TD1><TD2 valign="top" width="32.95454545454545%">PPP supports dialup interfaces over various modem and
line types.</TD2><TD3 valign="top" width="39.77272727272727%"><p>Currently, the i5/OS implementation of PPP does not support
IPv6.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compportrestrict"><A NAME="rzai2compipv4ipv6__compportrestrict" shape="rect"></A>port restrictions</strong></TD1><TD2 valign="top" width="32.95454545454545%">These iSeries panels allow a customer to configure
selected port number or port number ranges for TCP or UDP so that they are
only available for a specific profile.</TD2><TD3 valign="top" width="39.77272727272727%"><span>Same for IPv6. Port restrictions
for IPv6 are identical to those available in IPv4. </span></TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compports"><A NAME="rzai2compipv4ipv6__compports" shape="rect"></A>ports</strong></TD1><TD2 valign="top" width="32.95454545454545%">TCP and UDP have separate port spaces, each
identified by port numbers in the range 1-65535.</TD2><TD3 valign="top" width="39.77272727272727%">For IPv6, ports work the same as IPv4. Because
these are in a new address family, there are now four separate port spaces.
For example, there are two TCP port 80 spaces to which an application can
bind, one in AF_INET and one in AF_INET6.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compprivpubaddr"><A NAME="rzai2compipv4ipv6__compprivpubaddr" shape="rect"></A>private and public addresses</strong></TD1><TD2 valign="top" width="32.95454545454545%">All IPv4 addresses are public, except for
three address ranges that have been designated as private by IETF RFC 1918: <samp class="codeph">10.*.*.*
(10/8)</samp>, <samp class="codeph">172.16.0.0</samp> through <samp class="codeph">172.31.255.255
(172.16/12) </samp>, and <samp class="codeph">192.168.*.* (192.168/16)</samp>. Private
address domains are commonly used within organizations. Private addresses
cannot be routed across the Internet.</TD2><TD3 valign="top" width="39.77272727272727%">IPv6 has an analogous concept, but with important
differences.  <p>Addresses are public or temporary, previously termed anonymous.
See RFC 3041. Unlike IPv4 private addresses, temporary addresses can be globally
routed. The motivation is also different; IPv6 temporary addresses are meant
to shield the identity of a client when it initiates communication (a privacy
concern). Temporary addresses have a limited lifetime, and do not contain
an interface identifier that is a link (MAC) address. They are generally indistinguishable
from public addresses.</p>
<p>IPv6 has the notion of limited address scope
using its architected scope designations (see <A HREF="#rzai2compipv4ipv6__compaddrscope" shape="rect">address
scope</A>).</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compprotocoltable"><A NAME="rzai2compipv4ipv6__compprotocoltable" shape="rect"></A>protocol table</strong></TD1><TD2 valign="top" width="32.95454545454545%">On iSeries Navigator, a configurable table
that associates a protocol name with its assigned protocol number; for example,
UDP, 17.  The system is shipped with a small number of entries: IP, TCP, UDP,
ICMP.</TD2><TD3 valign="top" width="39.77272727272727%"><p>The table can be used with
IPv6 without change.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compqos"><A NAME="rzai2compipv4ipv6__compqos" shape="rect"></A>quality of service (QoS)</strong></TD1><TD2 valign="top" width="32.95454545454545%">Quality of service allows you to request
packet priority and bandwidth for TCP/IP applications.</TD2><TD3 valign="top" width="39.77272727272727%"><p>Currently, the i5/OS implementation
of QoS does not support IPv6.</p>
  </TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__comprenumber"><A NAME="rzai2compipv4ipv6__comprenumber" shape="rect"></A>renumbering</strong></TD1><TD2 valign="top" width="32.95454545454545%">Done by manual reconfiguration, with the
possible exception of DHCP. Generally, for a site or organization, a difficult
and troublesome process to avoid if possible.</TD2><TD3 valign="top" width="39.77272727272727%">Is an important architectural element of
IPv6, and is largely automatic, especially within the <samp class="codeph">/48</samp> prefix.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__comproute"><A NAME="rzai2compipv4ipv6__comproute" shape="rect"></A>route</strong></TD1><TD2 valign="top" width="32.95454545454545%">Logically, a mapping of a set of IP addresses
(might contain only one) to a physical interface and a single <span>next-hop</span> IP
address. IP packets whose destination address is defined as part of the set
are forwarded to the next hop using the line. IPv4 routes are associated with
an IPv4 interface, hence, an IPv4 address.  <p>The default route is *DFTROUTE.</p>
</TD2><TD3 valign="top" width="39.77272727272727%"><p>Conceptually, similar to
IPv4. One important difference: IPv6 routes are associated (bound) to a physical
interface (a link, such as ETH03) rather than an interface. One reason that
a route is associated with a physical interface is because source address
selection functions differently for IPv6 than for IPv4. See <A HREF="#rzai2compipv4ipv6__compsourceaddr" shape="rect">source
address selection</A>. </p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__comprip"><A NAME="rzai2compipv4ipv6__comprip" shape="rect"></A>Routing Information Protocol (RIP)</strong></TD1><TD2 valign="top" width="32.95454545454545%">RIP is a routing protocol supported by the routed daemon.</TD2><TD3 valign="top" width="39.77272727272727%">Currently, RIP does not support IPv6. IPv6 routing uses
static routes.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compservicestable"><A NAME="rzai2compipv4ipv6__compservicestable" shape="rect"></A>services table</strong></TD1><TD2 valign="top" width="32.95454545454545%">On the iSeries server, a configurable table
that associates a service name with a port and protocol; for example, service
name FTP-control, port 21, TCP and UDP.  <p>A large number of well-known services
are listed in the services table. Many applications use this table to determine
which port to use.</p>
</TD2><TD3 valign="top" width="39.77272727272727%">No changes are made to this table for IPv6.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compsnmp"><A NAME="rzai2compipv4ipv6__compsnmp" shape="rect"></A>Simple Network Management Protocol (SNMP)</strong></TD1><TD2 valign="top" width="32.95454545454545%">SNMP is a protocol for system management.</TD2><TD3 valign="top" width="39.77272727272727%"><p>Currently, the i5/OS implementation
of SNMP does not support IPv6. </p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compsocketapi"><A NAME="rzai2compipv4ipv6__compsocketapi" shape="rect"></A>sockets API</strong></TD1><TD2 valign="top" width="32.95454545454545%">These APIs are the way applications use TCP/IP.
Applications that do not need IPv6 are not affected by sockets changes to
support IPv6.</TD2><TD3 valign="top" width="39.77272727272727%">IPv6 enhances sockets so that applications
can now use IPv6, using a new address family: AF_INET6.  <p>The enhancements
have been designed so that existing IPv4 applications are completely unaffected
by IPv6 and API changes. Applications that want to support concurrent IPv4
and IPv6 traffic, or IPv6-only traffic, are easily accommodated using IPv4-mapped
IPv6 addresses of the form <samp class="codeph">::ffff:a.b.c.d</samp>, where <samp class="codeph">a.b.c.d</samp> is
the IPv4 address of the client. </p>
<p>The new APIs also include support for
converting IPv6 addresses from text to binary and from binary to text. </p>
<p>See <A HREF="../rzab6/uafinet6.htm" shape="rect">Use AF_INET6 address
family</A> for more information about sockets enhancements for IPv6.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compsourceaddr"><A NAME="rzai2compipv4ipv6__compsourceaddr" shape="rect"></A>source address selection</strong></TD1><TD2 valign="top" width="32.95454545454545%">An application may designate a source IP
(typically, using sockets <samp class="codeph">bind()</samp>) .  If it binds to INADDR_ANY,
a source IP is chosen based on the route.</TD2><TD3 valign="top" width="39.77272727272727%">As with IPv4, an application can designate
a source IPv6 address using <samp class="codeph">bind()</samp>. Similarly to IPv4, it
can let the system choose an IPv6 source address by using in6addr_any. But
since IPv6 lines have many IPv6 addresses, the internal method of choosing
a source IP is different.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compstartstop"><A NAME="rzai2compipv4ipv6__compstartstop" shape="rect"></A>starting and stopping</strong></TD1><TD2 valign="top" width="32.95454545454545%">Use STRTCP and ENDTCP to start or end TCP/IP.</TD2><TD3 valign="top" width="39.77272727272727%">Same as IPv4. IPv4 and IPv6 are not started
or stopped independently of one another or independently of TCP/IP. That is,
you start and stop all of TCP/IP, not just IPv4 or IPv6. <p>Any
IPv6 interfaces are automatically started if the AUTOSTART parameter = <samp class="codeph">*YES</samp> (the
default). IPv6 cannot be used or configured without IPv4. The IPv6 loopback
interface, <samp class="codeph">::1</samp>, will automatically be defined and activated
when IPv6 is started.</p>
</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__comptelnet"><A NAME="rzai2compipv4ipv6__comptelnet" shape="rect"></A>Telnet</strong></TD1><TD2 valign="top" width="32.95454545454545%">Telnet allows you to log on and use a remote
computer as though you were connected to it directly.</TD2><TD3 valign="top" width="39.77272727272727%"><span>Currently, the i5/OS implementation
of Telnet does not support IPv6.</span></TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__comptraceroute"><A NAME="rzai2compipv4ipv6__comptraceroute" shape="rect"></A>trace route</strong></TD1><TD2 valign="top" width="32.95454545454545%">Basic TCP/IP tool to do path determination.
Available using iSeries Navigator
and 5250.</TD2><TD3 valign="top" width="39.77272727272727%">Same for IPv6, and IPv6 is supported for
both 5250 and iSeries Navigator.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__comptransport"><A NAME="rzai2compipv4ipv6__comptransport" shape="rect"></A>transport layers</strong></TD1><TD2 valign="top" width="32.95454545454545%"><p>TCP, UDP, RAW. </p>
</TD2><TD3 valign="top" width="39.77272727272727%">The same transports exist in IPv6.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compunspecaddr"><A NAME="rzai2compipv4ipv6__compunspecaddr" shape="rect"></A>unspecified address</strong></TD1><TD2 valign="top" width="32.95454545454545%">Apparently, not defined, as such. Socket
programming uses <samp class="codeph">0.0.0.0</samp> as INADDR_ANY.</TD2><TD3 valign="top" width="39.77272727272727%">Defined as <samp class="codeph">::/128</samp> (128 0
bits). It is used as the source IP in some neighbor discovery packets, and
various other contexts, like sockets. Socket programming uses <samp class="codeph">::/128</samp> as <samp class="codeph">in6addr_any</samp>.</TD3></TR>
<TR><TD1 valign="top" width="27.27272727272727%"><strong id="rzai2compipv4ipv6__compvpn"><A NAME="rzai2compipv4ipv6__compvpn" shape="rect"></A>virtual private networking (VPN)</strong></TD1><TD2 valign="top" width="32.95454545454545%">Virtual private networking (using IPsec) allows you
to extend a secure, private network over an existing public network.</TD2><TD3 valign="top" width="39.77272727272727%"><p>Currently, the i5/OS implementation of VPN does not support
IPv6. </p>
</TD3></TR>
</TABLE>