One document matched: draft-boucadair-pcp-capability-03.xml
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<rfc category="std" docName="draft-boucadair-pcp-capability-03"
ipr="trust200902">
<front>
<title abbrev="CAPABILITY">Retrieving the Capabilities of a PCP-controlled
Device</title>
<author fullname="Mohamed Boucadair" initials="M." surname="Boucadair">
<organization>France Telecom</organization>
<address>
<postal>
<street></street>
<city>Rennes</city>
<region></region>
<code>35000</code>
<country>France</country>
</postal>
<email>mohamed.boucadair@orange.com</email>
</address>
</author>
<author fullname="Tirumaleswar Reddy" initials="T." surname="Reddy">
<organization abbrev="Cisco">Cisco Systems, Inc.</organization>
<address>
<postal>
<street>Cessna Business Park, Varthur Hobli</street>
<street>Sarjapur Marathalli Outer Ring Road</street>
<city>Bangalore</city>
<region>Karnataka</region>
<code>560103</code>
<country>India</country>
</postal>
<email>tireddy@cisco.com</email>
</address>
</author>
<date day="25" month="November" year="2013" />
<workgroup>PCP Working Group</workgroup>
<abstract>
<t>This document extends Port Control Protocol (PCP) with the ability to
retrieve the capabilities of PCP-controlled device: CAPABILITY
Option.</t>
</abstract>
<note title="Requirements Language">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in <xref
target="RFC2119">RFC 2119</xref>.</t>
</note>
</front>
<middle>
<section anchor="introduction" title="Introduction">
<t>This document extends the <xref target="RFC6887">base PCP </xref>
with a new feature to discover the capabilities of a PCP-controlled
device. Retrieving the capabilities of a PCP-controlled device would
allow to avoid error, provide a hint why some applications fails, help
select the OpCode to issue, etc.</t>
<t>This option can be elected to be defined as a new OpCode.</t>
</section>
<section anchor="capability_ie" title="CAPABILITY">
<t>The CAPABILITY option (Code: TBA, <xref target="capability"></xref>)
is used by a PCP Server to indicate to a requesting PCP Client the
capabilities it supports with regards to port forwarding operations.</t>
<t>One single Capability option is conveyed in the same PCP response
message even if several functions are co-located in the same
PCP-controlled device (e.g., NAT44 and NAT64, NAT44 and ports set
assignment capability, etc.).</t>
<t>This option, when received from a PCP Server, is used by a PCP Client
to constraint the content of its requests and therefore avoid
errors.</t>
<t><figure anchor="capability" title="Capability option">
<preamble></preamble>
<artwork><![CDATA[
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CAPABILITY | Reserved | Length=16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| Capability |
+-+ |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This Option:
Option Name: PCP Capabilities Option (CAPABILITY)
Number: TBA (IANA)
Purpose: Retrieve the capabilities of a PCP-controlled device
Valid for Opcodes: ANNOUNCE, MAP, PEER
Length: 16
May appear in: both request and response
Maximum occurrences: None
]]></artwork>
<postamble></postamble>
</figure></t>
<t>A-bit when set (i.e., 1) indicates the PCP Server supports
authentication. If this bit is set to 0, is indicates plain PCP is
supported.</t>
<t>The Capability Field is encoded in 127 bits. Each bit in the
Capability bit mask is used to represent the PCP-controlled device
capability. Several bits can be set if several functions are co-located
in the same device. The following values for the Capability field
are:</t>
<t><list style="empty">
<t>Bit #: Description</t>
<t>1: NAT44</t>
<t>2: Stateless NAT64 <xref target="RFC6145"></xref>.</t>
<t>4: Stateful NAT64 <xref target="RFC6146"></xref>.</t>
<t>8: A+P Port Range Router <xref target="RFC6346"></xref></t>
<t>9: Supports PORT_SET option <xref
target="I-D.ietf-pcp-port-set"></xref>. </t>
<t>16: IPv4 firewall.</t>
<t>32: IPv6 Firewall <xref target="RFC6092"></xref>.</t>
<t>64: NPTv6 <xref target="RFC6296"></xref>.</t>
<t>125: DSCP re-marking function.</t>
<t>126: FLOWDATA-aware function (<xref
target="I-D.wing-pcp-flowdata"></xref>).</t>
<t>127: ILNP Translator <xref target="RFC6740"></xref>.</t>
</list></t>
</section>
<section title="PCP Client/Server Behavior">
<t>This section specifies the behavior of the PCP Client and the PCP
Server to handle the CAPABILITY Option.</t>
<t>The PCP Server MAY be configured to return the CAPABILITY Option even
if it is not included in the request.</t>
<t>Once the PCP Client is configured with its PCP Server(s), it MAY
issue an ANNOUNCE OpCode which enclose a CAPABILITY Option. Sending the
ANNOUNCE OpCode and the CAPABILITY Option allows the PCP Client to
determine whether the PCP Server is alive and also to retrieve its
capabilities. Based on the received capabilities, the PCP Client may
decide to tune its requests (e.g., <xref target="usage"></xref>) and
decide whether all PCP Servers need to be contacted in parallel or only
a subset of them should be contacted.</t>
<t>Upon receipt of a PCP request from a PCP Client requiring the PCP
Server to enforce an operation beyond its capabilities, the PCP Server
MAY return an error code together with the CAPABILITY option.</t>
<t>When a new PCP Server joins the network then it MAY send an ANNOUNCE
OpCode with its capabilities (i.e., CAPABILITY Option).</t>
</section>
<section anchor="usage" title="Option Usage">
<t>Below are provided examples of the CAPABILITY Option usage:<list
style="symbols">
<t>In an IPv6 network with NPTv6 <xref target="RFC6296"></xref>,
Firewalls implementing the PCP Server are on different devices: the
PCP Client learns of the available PCP Servers by using DHCP <xref
target="I-D.ietf-pcp-dhcp"></xref> or any other PCP Server discovery
technique defined in future specifications. PCP Client learns the
PCP Server capabilities using CAPABILITY Option. The PCP Client
sends MAP PCP request to PCP-controlled NPTv6 device with Internal
Port=0 and Protocol=0 (which means 'all ports for all protocols') to
find the external IP address. This PCP request has to be sent only
once since NPTv6 is stateless and provides a 1:1 relationship
between addresses in the "inside" and "outside" prefixes. The PCP
Client will send PCP re-request to NTPv6 only before the Assigned
Lifetime of the MAP response expires or when the host embedding the
PCP Client acquires a new IPv6 address using "inside" prefix.
However PCP Client will send MAP/PEER requests to Firewall to
create/delete dynamic outbound mapping or use PCP instead of its
default application keep-alives to maintain the Firewall state
alive.<figure anchor="figure1"
title="NPTv6 and FW not collocated with PCP server Capability">
<artwork><![CDATA[ PCP
Client __________
+-----------+ +------+ +------+ / \ +-----------+
|Application|___| NPTv6|___| FW |____| Internet |___|Application|
| Client | | | | | | | | Server |
+-----------+ +------+ +------+ \__________/ +-----------+
]]></artwork>
</figure></t>
<t>In a network with NAT64 <xref target="RFC6146"></xref>, Firewall
implementing PCP servers are on different devices: IPv6-only PCP
Client can send PREFIX64 PCP Option <xref
target="I-D.ietf-pcp-nat64-prefix64"></xref> only to the
PCP-controlled NAT64 device to learn the Prefix64(s) used to build
IPv4-embedded IPv6 addresses.</t>
<t>Multiple PCP-controlled devices: See <xref
target="figure2"></xref> the example of a network deploying several
techniques to ensure interconnection with IPv4, provide IPv6-only
connectivity, etc. Of course, one can argue this configuration is no
realistic. <figure anchor="figure2"
title="Multiple PCP-controlled devoce">
<artwork><![CDATA[ +-----+
______|NPTv6|___________
/ +-----+ \
| |
| +-----+
+-----------+ +------+ | | PRR |
|Application|___| IPv6 |______| SP Network +-----+
|PCP Client| | FW | | |
+-----------+ +------+ | +------+
| | NAT64|
+-----------+ +-------+ | | + |
|PCP Client |___|A+P NAT|_____| | FW |
+-----------+ +-------+ | +-----+ +------+
\______|NPTv6|___________/
+-----+
]]></artwork>
</figure></t>
<t>In a IPv6 network with ILNP translator <xref
target="RFC6740"></xref>, Firewall implementing PCP servers are on
different devices. PCP client needs to send PCP request only to the
PCP-controlled ILNP translator to find Global Locators associated
with Internal Locators.</t>
<t>When the PCP-controlled device is a PRR, the PCP Client should
use PORT_SET <xref target="I-D.ietf-pcp-port-set"></xref>
option.</t>
</list></t>
</section>
<section anchor="security" title="Security Considerations">
<t>Security considerations discussed in <xref target="RFC6887"></xref>
must be considered.</t>
</section>
<section anchor="iana" title="IANA Considerations">
<t>The following PCP Option Code is to be allocated in the
optional-to-process range (the registry is maintained in
http://www.iana.org/assignments/pcp-parameters/pcp-parameters.xml#options):<list
style="empty">
<t>CAPABILITY</t>
</list>A sub-registry is required to track the set of capabilities of
PCP-controlled devices. </t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include="reference.RFC.2119"?>
<?rfc include='reference.RFC.6887'?>
<?rfc include='reference.RFC.6145'?>
<?rfc include='reference.RFC.6146'
?>
</references>
<references title="Informative References">
<?rfc include='reference.I-D.ietf-pcp-port-set'?>
<?rfc include='reference.I-D.ietf-opsawg-firewalls'?>
<?rfc include='reference.I-D.ietf-pcp-nat64-prefix64'?>
<?rfc include='reference.I-D.wing-pcp-flowdata'?>
<?rfc include='reference.RFC.6346'?>
<?rfc include='reference.RFC.6092'?>
<?rfc include='reference.RFC.6296'?>
<?rfc include='reference.I-D.ietf-pcp-dhcp'
?>
<?rfc include='reference.RFC.6740'?>
</references>
<!--
-->
</back>
</rfc>
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