One document matched: draft-ietf-radext-ip-port-radius-ext-02.xml
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<rfc category="std" docName="draft-ietf-radext-ip-port-radius-ext-02"
ipr="trust200902">
<front>
<title abbrev="RADIUS Extensions for IP Port ">RADIUS Extensions for IP
Port Configuration and Reporting</title>
<author fullname="Dean Cheng" initials="D." surname="Cheng">
<organization>Huawei</organization>
<address>
<postal>
<street>2330 Central Expressway</street>
<city>Santa Clara</city>
<region>California</region>
<code>95050</code>
<country>USA</country>
</postal>
<email>dean.cheng@huawei.com</email>
</address>
</author>
<author fullname="Jouni Korhonen" initials="J." surname="Korhonen">
<organization>Broadcom</organization>
<address>
<postal>
<street>Porkkalankatu 24</street>
<city>FIN-00180 Helsinki</city>
<code></code>
<country>Finland</country>
</postal>
<email>jouni.nospam@gmail.com</email>
</address>
</author>
<author fullname="Mohamed Boucadair" initials="M." surname="Boucadair">
<organization>France Telecom</organization>
<address>
<postal>
<street></street>
<city>Rennes</city>
<country>France</country>
</postal>
<email>mohamed.boucadair@orange.com</email>
</address>
</author>
<author fullname="Senthil Sivakumar" initials="S." surname="Sivakumar">
<organization>Cisco Systems</organization>
<address>
<postal>
<street>7100-8 Kit Creek Road</street>
<city>Research Triangle Park</city>
<region>North Carolina</region>
<country>USA</country>
</postal>
<email>ssenthil@cisco.com</email>
</address>
</author>
<date year="2014" />
<abstract>
<t>This document defines three new RADIUS attributes. For devices that
implementing IP port ranges, these attributes are used to communicate
with a RADIUS server in order to configure and report TCP/UDP ports and
ICMP identifiers, as well as mapping behavior for specific hosts. This
mechanism can be used in various deployment scenarios such as CGN
(Carrier Grade NAT), NAT64, Provider WLAN Gateway, etc.</t>
<t>This document does not make any assumption about the deployment
context.</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 title="Introduction">
<t>In a broadband network, customer information is usually stored on a
RADIUS server <xref target="RFC2865"></xref> and at the time when a user
initiates an IP connection request, the RADIUS server will populate the
user's configuration information to the Network Access Server (NAS),
which is usually co-located with the Border Network Gateway (BNG), after
the connection request is granted. The Carrier Grade NAT (CGN) function
may also be implemented on the BNG, and therefore CGN TCP/UDP port (or
ICMP identifier) mapping behavior can be configured on the RADIUS server
as part of the user profile, and populated to the NAS in the same
manner. In addition, during the operation, the CGN can also convey
port/identifier mapping behavior specific to a user to the RADIUS
server, as part of the normal RADIUS accounting process.</t>
<t>The CGN device that communicates with a RADIUS server using RADIUS
extensions defined in this document may perform NAT44 <xref
target="RFC3022"></xref>, NAT64 <xref target="RFC6146"></xref>, or
Dual-Stack Lite AFTR <xref target="RFC6333"> </xref> function.</t>
<t>For the CGN case, when IP packets traverse a CGN device, it would
perform TCP/UDP source port mapping or ICMP identifier mapping as
required. A TCP/ UDP source port or ICMP identifier, along with source
IP address, destination IP address, destination port and protocol
identifier if applicable, uniquely identify a session. Since the number
space of TCP/UDP ports and ICMP identifiers in CGN's external realm is
shared among multiple users assigned with the same IPv4 address, the
total number of a user's simultaneous IP sessions is likely to be
subject to port quota (see Section 5 of <xref
target="RFC6269"></xref>).</t>
<t>The attributes defined in this document may also be used to report
the assigned port range in some deployments such as Provider WLAN <xref
target="I-D.gundavelli-v6ops-community-wifi-svcs"></xref>. For example,
a visiting host can be managed by a CPE (Customer Premises Equipment )
which will need to report the assigned port range to the service
platform. This is required for identification purposes (see WT-146 for
example).</t>
<t>This document proposes three new attributes as RADIUS protocol's
extensions, and they are used for separate purposes as follows:</t>
<t><list style="numbers">
<t>IP-Port-Limit: This attribute may be carried in RADIUS
Acces-Accept, Access-Request, Accounting-Request or CoA-Request
packet. The purpose of this attribute is to limit the total number
of TCP/UDP ports and/or ICMP identifiers that an IP subscriber can
use, associated with an IPv4 address.</t>
<t>IP-Port-Range: This attribute may be carried in RADIUS
Accounting-Request packet. The purpose of this attribute is to
report by an address sharing device (e.g., a CGN) to the RADIUS
server the range of TCP/UDP ports and/or ICMP identifiers that have
been allocated or deallocated associated with a given IPv4 address
for a subscriber.</t>
<t>IP-Port-Forwarding-Map: This attribute may be carried in RADIUS
Access-Accept, Access-Request, Accounting-Request or CoA-Request
packet. The purpose of this attribute is to specify how a TCP/UDP
port (or an ICMP identifier) mapping to another TCP/UDP port (or an
ICMP identifier), and each is associated with its respective IPv4
address.</t>
</list></t>
<t>This document was constructed using the <xref
target="RFC2629"></xref> .</t>
</section>
<section title="Terminology">
<t>This document makes use if the following terms:<list style="symbols">
<t>IP Port: refers to the port numbers of IP transport protocols,
including TCP port, UDP port and ICMP identifier.</t>
<t>IP Port Type: refers to one of the following: (1)TCP/UDP port and
ICMP identifier, (2)TCP port and UDP port, (3) TCP port, (4) UDP
port, or (5)ICMP identifier.</t>
<t>IP Port Limit: denotes the maximum number of IP ports for a
specific port type, that a device supporting port ranges can use
when performing port number mapping for a specific user.</t>
<t>IP Port Range: specifies a set of contiguous IP ports, indicated
by the smallest numerical number and the largest numerical number,
inclusively.</t>
<t>Internal IP Address: refers to the IP address that is used as a
source IP address in an outbound IP packet sent towards a device
supporting port ranges in the internal realm. In the IPv4 case, it
is typically a private address <xref target="RFC1918"></xref>.</t>
<t>External IP Address: refers to the IP address that is used as a
source IP address in an outbound IP packet after traversing a device
supporting port ranges in the external realm. In the IPv4 case, it
is typically a global routable IP address.</t>
<t>Internal Port: is a UDP or TCP port, or an ICMP identifier, which
is allocated by a host or application behind a device supporting
port ranges for an outbound IP packet in the internal realm.</t>
<t>External Port: is a UDP or TCP port, or an ICMP identifier, which
is allocated by a device supporting port ranges upon receiving an
outbound IP packet in the internal realm, and is used to replace the
internal port that is allocated by a user or application.</t>
<t>External realm: refers to the networking segment where IPv4
public addresses are used in respective of the device supporting
port ranges.</t>
<t>Internal realm: refers to the networking segment that is behind a
device supporting port ranges and where IPv4 private addresses are
used.</t>
<t>Mapping: associates with a device supporting port ranges for a
relationship between an internal IP address, internal port and the
protocol, and an external IP address, external port, and the
protocol.</t>
<t>Port-based device: a device that is capable of providing IP
address and IP port mapping services and in particular, with the
granularity of one or more subsets within the 16-bit IP port number
range. A typical example of this device is a CGN, CPE, Provider WLAN
Gateway, etc.</t>
</list></t>
<t>Note the terms "internal IP address", "internal port", "internal
realm", "external IP address", "external port", "external realm", and
"mapping" and their semantics are the same as in <xref target="RFC6887">
</xref>, and <xref target="RFC6888"></xref>.</t>
</section>
<section anchor="attrs" title="Extensions of RADIUS Attributes and TLVs">
<t>These three new attributes are defined in the following
sub-sections:</t>
<t><list style="numbers">
<t>IP-Port-Limit Attribute</t>
<t>IP-Port-Range Attribute</t>
<t>IP-Port-Forwarding-Map Attribute</t>
</list></t>
<t>All these attributes are allocated from the RADIUS "Extended Type"
code space per <xref target="RFC6929"></xref>.</t>
<t> [Editor's notes - A comment was received on suggestion to map Radius TLVs
to IPFIX Elements whenever possible. Authors are working on details on this
for the next revision.] </t>
<section title="Extended Attributes for IP Ports">
<section anchor="sessiontype"
title="Extended-Type and IP-Port-Type TLV">
<t>This section defines a new Extended-Type and an IP-Port-Type TLV
(see <xref target="ext_type"></xref>). </t>
<t>The IP port type may be one of the following:</t>
<t><list style="symbols">
<t>TCP port, UDP port, and ICMP identifier</t>
<t>TCP port and UDP port</t>
<t>TCP port</t>
<t>UDP port</t>
<t>ICMP identifier</t>
</list></t>
<figure anchor="ext_type">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Extended-Type | TLV1-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV1-Length | Value...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>Type:</t>
<t><list counter="1" hangIndent="5">
<t>TBA1 - Extended-Type-1 (241), Extended-Type-2 (242),
Extended-Type-3 (243), or Extended-Type-4 (244) per <xref
target="RFC6929"></xref>.</t>
</list></t>
<t>Length:</t>
<t><list counter="1" hangIndent="5">
<t>This field indicates the total length in bytes of all fields
this attribute, including the Type, Length, Extended-Type, and
the embedded TLVs.</t>
</list></t>
<t>Extended-Type:</t>
<t><list counter="1" hangIndent="5">
<t>TBA2.</t>
</list></t>
<t>TLV1-Type:<list counter="1" hangIndent="5">
<t>Type field of IP-Port-Type TLV. This one byte field indicates
the IP port type as follows:</t>
<t>TBA2-1:<list counter="1" hangIndent="5">
<t>Refer to TCP port, UDP port, and ICMP identifier as a
whole.</t>
</list></t>
<t>TBA2-2:<list counter="1" hangIndent="5">
<t>Refer to TCP port and UDP port as a whole.</t>
</list></t>
<t>TBA2-3:<list counter="1" hangIndent="5">
<t>Refer to TCP port only.</t>
</list></t>
<t>TBA2-4:<list counter="1" hangIndent="5">
<t>Refer to UDP port only.</t>
</list></t>
<t>TBA2-5:<list counter="1" hangIndent="5">
<t>Refer to ICMP identifier only.</t>
</list></t>
</list></t>
<t>TLV1-Length:</t>
<t><list counter="1" hangIndent="5">
<t>Length field of IP-Port-Type TLV. This field indicates the
total length in bytes of the TLV1, including the field of
TLV1-Type, TLV1-Length, and the Value.</t>
</list></t>
<t>Value:</t>
<t><list counter="1" hangIndent="5">
<t>Value field of IP-Port-Type TLV. This field contains one or
more TLVs, refer to <xref target="sessionlimit"></xref>, <xref
target="sessionrange"></xref>, <xref target="portmap"></xref>
for details.</t>
<t>The interpretation of this field is determined by the
identifier of "TBA1.TBA2.{TBA2-1..TBA2-5} along with the
embedded TLVs.</t>
</list></t>
</section>
<section anchor="sessionlimit" title="IP-Port-Limit Attribute">
<t>This attribute contains the Extended-Type and IP-Port-Type TLV
defined in <xref target="sessiontype"></xref>, along with the
embedded IP-Port-Limit TLV and IP-Port-Ext-IPv4-Addr TLV, defined in
<xref target="TLV2"></xref> and <xref target="TLV3"></xref>,
respectively. It specifies the maximum number of IP ports, as
indicated in IP-Port-Limit TLV, of a specific port type, and
associated with a given IPv4 address, as indicated in
IP-Port-Ext-IPv4-Addr TLV for an end user. Note that when
IP-Port-Ext-IPv4-Addr TLV is not included as part of the
IP-Port-Limit Attribute, the port limit is applied to all the IPv4
addresses managed by the port device, e.g., a CGN or NAT64
device.</t>
<t>The IP-Port-Limit Attribute MAY appear in an Access-Accept
packet. It MAY also appear in an Access-Request packet as a hint by
the device supporting port ranges, which is co-allocated with the
NAS, to the RADIUS server as a preference, although the server is
not required to honor such a hint.</t>
<t>The IP-Port-Limit Attribute MAY appear in a CoA-Request
packet.</t>
<t>The IP-Port-Limit Attribute MAY appear in an Accounting-Request
packet.</t>
<t>The IP-Port-Limit Attribute MUST NOT appear in any other RADIUS
packets.</t>
<t>The format of the IP-Port-Limit Attribute is shown in <xref
target="limit"></xref>. The fields are transmitted from left to
right.</t>
<figure anchor="limit">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Extended-Type | TLV1-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV1-Length | Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>Type:</t>
<t><list counter="1" hangIndent="5">
<t>TBA1 - Extended-Type-1 (241), Extended-Type-2 (242),
Extended-Type-3 (243), or Extended-Type-4 (244) per <xref
target="RFC6929"></xref>.</t>
</list>Length: <list counter="1" hangIndent="5">
<t>This field indicates the total length in bytes of all fields
of this attribute, including the Type, Length, Extended-Type,
and the entire length of the embedded TLVs.</t>
</list></t>
<t>Extended-Type:<list counter="1" hangIndent="5">
<t>TBA2 - This one byte field contains a value that indicates
the IP port type, refer to <xref target="sessiontype"></xref>
for detail.</t>
</list></t>
<t>TLV1-Type:<list counter="1" hangIndent="5">
<t>TBA2-1, TBA2-2, TBA2-3, TBA2-4, or TBA2-5. Refer to <xref
target="sessiontype"></xref> for detail.</t>
</list></t>
<t>TLV1-Length:<list counter="1" hangIndent="5">
<t>This field indicates the total length in bytes of the TLV1,
including the field of TLV1-Type, TLV1-Length, and the entire
length of the embedded TLVs.</t>
</list></t>
<t>Value:<list counter="1" hangIndent="5">
<t>This field contains a set of TLVs as follows:</t>
<t>IP-Port-Limit TLV:<list counter="1" hangIndent="5">
<t>This TLV contains the maximum number of IP ports of a
specific IP port type and associated with a given IPv4
address for an end user. This TLV must be included in the
IP-Port-Limit Attribute. Refer to <xref
target="TLV2"></xref>.</t>
</list></t>
<t>IP-Port-Ext-IPv4-Addr TLV:<list counter="1" hangIndent="5">
<t>This TLV contains the IPv4 address that is associated
with the IP port limit contained in the IP-Port-Limit TLV.
This TLV is optionally included as part of the IP-Port-Limit
Attribute. Refer to <xref target="TLV3"></xref>.</t>
</list></t>
</list></t>
<t>IP-Port-Limit attribute is associated with the following
identifier: Type(TBA1).Extended-Type(TBA2).IP-Port-Type
TLV{TBA2-1..TBA2-5}.[IP-Port-Limit TLV(TBA3), {IP-Port-Ext-IPv4-Addr
TLV (TBA4)}].</t>
</section>
<section anchor="sessionrange" title="IP-Port-Range Attribute">
<t>This attribute contains the Extended-Type and IP-Port-Type TLV
defined in <xref target="sessiontype"></xref>, along with a set of
embedded TLVs defined in <xref target="TLV8"></xref>
(IP-Port-Range-Start TLV), <xref target="TLV9"></xref>
(IP-Port-Range-End TLV), <xref target="TLV7"></xref> (IP-Port-Alloc
TLV), <xref target="TLV3"></xref> (IP-Port-Ext-IPv4-Addr TLV), and
<xref target="TLV10"></xref> (IP-Port-Local-Id TLV). It contains a
range of contiguous IP ports of a specific port type and associated
with an IPv4 address that are either allocated or deallocated by a
device for a given subscriber, and the information is intended to
send to RADIUS server.</t>
<t>This attribute can be used to convey a single IP port number; in
such case IP-Port-Range-Start and IP-Port-Range-End conveys the same
value.</t>
<t>Within an IP-Port-Range Attribute, the IP-Port-Alloc TLV is
always included. For port allocation, both IP-Port-Range-Start TLV
and IP-Port-Range-End TLV must be included; for port deallocation,
the inclusion of these two TLVs is optional and if not included, it
implies that all ports that are previously allocated are now
deallocated. Both IP-Port-Ext-IPv4-Addr TLV and IP-Port-Local-Id TLV
are optional and if included, they are used by a port device (e.g.,
a CGN device) to identify the end user.</t>
<t>The IP-Port-Range Attribute MAY appear in an Accounting-Request
packet.</t>
<t>The IP-Port-Range Attribute MUST NOT appear in any other RADIUS
packets.</t>
<t>The format of the IP-Port-Range Attribute format is shown in
<xref target="range"></xref>. The fields are transmitted from left
to right.</t>
<figure anchor="range">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Extended-Type | TLV1-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV1-Length | Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>Type:</t>
<t><list counter="1" hangIndent="5">
<t>TBA1 - Extended-Type-1 (241), Extended-Type-2 (242),
Extended-Type-3 (243), or Extended-Type-4 (244) per <xref
target="RFC6929"></xref></t>
</list>Length: <list counter="1" hangIndent="5">
<t>This field indicates the total length in bytes of all fields
of this attribute, including the Type, Length, Extended-Type,
and the entire length of the embedded TLVs.</t>
</list></t>
<t>Extended-Type:<list counter="1" hangIndent="5">
<t>TBA2 - This one byte field contains a value that indicates
the IP port type, refer to <xref target="sessiontype"></xref>
for detail.</t>
</list></t>
<t>TLV1-Type:<list counter="1" hangIndent="5">
<t>TBA2-1, TBA2-2, TBA2-3, TBA2-4, or TBA2-5. Refer to <xref
target="sessiontype"></xref> for detail.</t>
</list></t>
<t>TLV1-Length:<list counter="1" hangIndent="5">
<t>This field indicates the total length in bytes of the TLV1,
including the field of TLV1-Type, TLV1-Length, and the entire
length of the embedded TLVs.</t>
</list></t>
<t>Value:<list counter="1" hangIndent="5">
<t>This field contains a set of TLVs as follows:</t>
<t>IP-Port-Alloc TLV:<list counter="1" hangIndent="5">
<t>This TLV contains a flag to indicate that the range of
the specified IP ports for either allocation or
deallocation. This TLV must be included as part of the
IP-Port-Range Attribute. Refer to <xref
target="TLV7"></xref>.</t>
</list></t>
<t>IP-Port-Range-Start TLV:<list counter="1" hangIndent="5">
<t>This TLV contains the smallest port number of a range of
contiguous IP ports. To report the port allocation, this TLV
must be included together with IP-Port-Range-End TLV as part
of the IP-Port-Range Attribute. Refer to <xref
target="TLV8"></xref>.</t>
</list></t>
<t>IP-Port-Range-End TLV:<list counter="1" hangIndent="5">
<t>This TLV contains the largest port number of a range of
contiguous IP ports. To report the port allocation, this TLV
must be included together with IP-Port-Range-Start TLV as
part of the IP-Port-Range Attribute. Refer to <xref
target="TLV9"></xref>.</t>
</list></t>
<t>IP-Port-Ext-IPv4-Addr TLV:<list counter="1" hangIndent="5">
<t>This TLV contains the IPv4 address that is associated
with the IP port range, as collectively indicated in the
IP-Port-Range-Start TLV and the IP-Port-Range-End TLV. This
TLV is optionally included as part of the IP-Port-Range
Attribute. Refer to <xref target="TLV3"></xref>.</t>
</list></t>
<t>IP-Port-Local-Id TLV:<list counter="1" hangIndent="5">
<t>This TLV contains a local session identifier at the
customer premise, such as MAC address, interface ID, VLAN
ID, PPP sessions ID, VRF ID, IPv6 address/prefix, etc. This
TLV is optionally included as part of the IP-Port-Range
Attribute. Refer to <xref target="TLV10"></xref>.</t>
</list></t>
</list></t>
<t>The IP-Port-Range attribute is associated with the following
identifier: Type(TBA1).Extended-Type(TBA2).IP-Port-Type
TLV{TBA2-1..TBA2-5}.[IP-Port-Alloc TLV(TBA8), {IP-Port-Range-Start
TLV (TBA9), IP-Port-Range-End TLV (TBA10)}, {IP-Port-Ext-IPv4-Addr
TLV (TBA4)}, {IP-Port-Local-Id TLV (TBA11)}].</t>
</section>
<section anchor="portmap" title="IP-Port-Forwarding-Map Attribute">
<t>This attribute contains the Extended-Type and IP-Port-Type TLV
defined in <xref target="sessiontype"></xref>,along with a set of
embedded TLVs defined in <xref target="TLV5"></xref>
(IP-Port-Int-Port TLV), <xref target="TLV6"></xref>
(IP-Port-Ext-Port TLV), <xref target="TLV4"></xref>
(IP-Port-Int-IP-Addr TLV), <xref
target="TLV10"></xref>(IP-Port-Local-Id TLV) and <xref
target="TLV3"></xref> (IP-Port-Ext-IP-Addr TLV). The attribute
contains a 2-byte IP internal port number that is associated with an
internal IPv4 or IPv6 address, or a locally significant identifier
at the customer site, and a 2-byte IP external port number that is
associated with an external IPv4 address. The internal IPv4 or IPv6
address, or the local identifier must be included; the external IPv4
address may also be included.</t>
<t>The IP-Port-Forwarding-Map Attribute MAY appear in an
Access-Accept packet. It MAY also appear in an Access-Request packet
as a hint by the device supporting port mapping, which is
co-allocated with the NAS, to the RADIUS server as a preference,
although the server is not required to honor such a hint.</t>
<t>The IP-Port-Forwarding-Map Attribute MAY appear in a CoA-Request
packet.</t>
<t>The IP-Port-Forwarding-Map Attribute MAY also appear in an
Accounting-Request packet.</t>
<t>The attribute MUST NOT appear in any other RADIUS packet.</t>
<t>The format of the IP-Port-Forwarding-Map Attribute is shown in
<xref target="map"></xref>. The fields are transmitted from left to
right.</t>
<figure anchor="map">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Extended-Type | TLV1-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV1-Length | Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>Type:</t>
<t><list counter="1" hangIndent="5">
<t>TBA1 - Extended-Type-1 (241), Extended-Type-2 (242),
Extended-Type-3 (243), or Extended-Type-4 (244) per <xref
target="RFC6929"></xref></t>
</list>Length: <list counter="1" hangIndent="5">
<t>This field indicates the total length in bytes of all fields
of this attribute, including the Type, Length, Extended-Type,
and the entire length of the embedded TLVs.</t>
</list></t>
<t>Extended-Type:<list counter="1" hangIndent="5">
<t>This one byte field contains a value that indicates the IP
port type, refer to <xref target="sessiontype"></xref> for
details.</t>
</list></t>
<t>TLV1-Type:<list counter="1" hangIndent="5">
<t>TBA2-1, TBA2-2, TBA2-3, TBA2-4, or TBA2-5. Refer to <xref
target="sessiontype"></xref> for detail.</t>
</list></t>
<t>TLV1-Length:<list counter="1" hangIndent="5">
<t>This field indicates the total length in bytes of the TLV1,
including the field of TLV1-Type, TLV1-Length, and the entire
length of the embedded TLVs.</t>
</list></t>
<t>Value:<list counter="1" hangIndent="5">
<t>This field contains a set of TLVs as follows:</t>
<t>IP-Port-Int-Port TLV:<list counter="1" hangIndent="5">
<t>This TLV contains an internal IP port number associated
with an internal IPv4 or IPv6 address. This TLV must be
included together with IP-Port-Ext-Port TLV as part of the
IP-Port-Forwarding-Map attribute. Refer to <xref
target="TLV5"></xref>.</t>
</list></t>
<t>IP-Port-Ext-Port TLV:<list counter="1" hangIndent="5">
<t>This TLV contains an external IP port number associated
with an external IPv4 address. This TLV must be included
together with IP-Port-Int-Port TLV as part of the
IP-Port-Forwarding-Map attribute. Refer to <xref
target="TLV6"></xref>.</t>
</list></t>
<t>IP-Port-Int-IP-Addr TLV:<list counter="1" hangIndent="5">
<t>This TLV contains an IPv4 or IPv6 address that is
associated with the internal IP port number contained in the
IP-Port-Int-Port TLV. Either this TLV or IP-Port-Local-Id
TLV must be included as part of the IP-Port-Forwarding-Map
Attribute. Refer to <xref target="TLV4"></xref>.</t>
</list></t>
<t>IP-Port-Local-Id TLV:<list counter="1" hangIndent="5">
<t>This TLV contains a local session identifier at the
customer premise, such as MAC address, interface ID, VLAN
ID, PPP sessions ID, VRF ID, IPv6 address/prefix, etc.
Either this TLV or IP-Port-Int-IP-Addr TLV must be included
as part of the IP-Port-Forwarding-Map Attribute. Refer to
<xref target="TLV10"></xref>.</t>
</list></t>
<t>IP-Port-Ext-IPv4-Addr TLV:<list counter="1" hangIndent="5">
<t>This TLV contains an IPv4 address that is associated with
the external IP port number contained in the
IP-Port-Ext-Port TLV. This TLV may be included as part of
the IP-Port-Forwarding-Map Attribute. Refer to <xref
target="TLV3"></xref>.</t>
</list></t>
</list></t>
<t>The IP-Port-Forwarding-Map attribute is associated with the
following identifier: Type(TBA1).Extended-Type(TBA2).IP-Port-Type
TLV{TBA2-1..TBA2-5}.[IP-Port-Int-Port TLV(TBA6), IP-Port-Ext-Port
TLV(TBA7), {IP-Port-Int-IP-Addr TLV (TBA5)}, {IP-Port-Ext-IPv4-Addr
TLV (TBA4)}].</t>
</section>
</section>
<section title="RADIUS TLVs for IP Ports">
<section anchor="TLV2" title="IP-Port-Limit TLV">
<t>This TLV (<xref target="tlv"></xref>) uses the format defined in
<xref target="RFC6929"></xref>. Its Value field contains a 2-byte
integer called IP-Port-Limit, which indicates the maximum number of
ports of a specified IP-Port-Type and associated with a given IPv4
address assigned to a subscriber.</t>
<t>IP-Port-Limit TLV is included as part of the IP-Port-Limit
Attribute (refer to <xref target="sessionlimit"></xref>).</t>
<t>Note that IP-Port-Limit TLV is embedded within IP-Port-Type TLV
(refer to <xref target="sessiontype"></xref>) for detail.</t>
<figure anchor="tlv">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV2-Type | TLV2-Length | IP-Port-Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>TLV2-Type:<list counter="1" hangIndent="5">
<t>TBA3: The type field for IP-Port-Limit TLV.</t>
</list></t>
<t>TLV2-Length:<list counter="1" hangIndent="5">
<t>This field indicates the total length in bytes of the TLV2,
including the field of TLV2-Type, TLV2-Length, and the Value
field, i.e., IP-Port-Limit.</t>
</list></t>
<t>IP-Port-Limit:<list counter="1" hangIndent="5">
<t>2-byte integer. This field contains the maximum number of IP
ports of which, the port type is specified by container
IP-Port-Type TLV.</t>
</list></t>
</section>
<section anchor="TLV3" title="IP-Port-Ext-IPv4-Addr TLV">
<t>This TLV (<xref target="tlv3"></xref>) uses the format defined
in<xref target="RFC6929"> </xref>. Its Value field contains a 4-byte
External IPv4 address.</t>
<t>IP-Port-Ext-IPv4-Addr TLV can be included as part of the
IP-Port-Limit Attribute (refer to <xref
target="sessionlimit"></xref>), IP-Port-Range Attribute (refer to
<xref target="sessionrange"></xref>), and IP-Port-Forwarding-Map
Attribute (refer to <xref target="portmap"></xref>).</t>
<t>Note that IP-Port-Ext-IPv4-Addr TLV is embedded within
IP-Port-Type TLV (refer to <xref target="sessiontype"></xref>) for
detail.</t>
<figure anchor="tlv3">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV3-Type | TLV3-Length | IP-Port-Ext-IPv4-Addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP-Port-Ext-IPv4-Addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>TLV3-Type:<list counter="1" hangIndent="5">
<t>TBA4: The type field for IP-Port-IPv4-Addr TLV.</t>
</list></t>
<t>TLV3-Length:<list counter="1" hangIndent="5">
<t>6. The Length field for IP-Port-IPv4-Addr TLV.</t>
</list></t>
<t>IP-Port-Ext-IPv4-Addr:<list counter="1" hangIndent="5">
<t>4-byte integer. This field contains the IPv4 address that is
associated with the range of IP ports.</t>
</list></t>
</section>
<section anchor="TLV4" title="IP-Port-Int-IP-Addr TLV">
<t>This TLV (<xref target="tlv4"></xref>) uses format defined in
<xref target="RFC6929"> </xref>. Its Value field contains an
internal IPv4 or IPv6 address.</t>
<t>IP-Port-Int-IP-Addr TLV can be included as part of the
IP-Port-Forwarding-Map Attribute (refer to <xref
target="portmap"></xref>).</t>
<t>Note that IP-Port-Int-IP-Addr TLV is embedded within IP-Port-Type
TLV (refer to <xref target="sessiontype"></xref>) for detail.</t>
<figure anchor="tlv4">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV4-Type | TLV4-Length | IP-Port-Int-IP-Addr....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>TLV4-Type:<list counter="1" hangIndent="5">
<t>TBA5: The type field for IP-Port-Int-IP-Addr TLV.</t>
</list></t>
<t>TLV4-Length:<list counter="1" hangIndent="5">
<t>6 or 18 bytes. The Length field for IP-Port-Int-IP-Addr
TLV.</t>
</list></t>
<t>IP-Port-Int-IP-Addr:<list counter="1" hangIndent="5">
<t>4 byte integer for IPv4 address or 16 byte for IPv6
address.</t>
</list></t>
</section>
<section anchor="TLV5" title="IP-Port-Int-Port TLV">
<t>This TLV (<xref target="tlv5"></xref>) uses format defined in
<xref target="RFC6929"> </xref>. Its Value field contains an
internal IP port number that is associated with an internal IPv4 or
IPv6 address.</t>
<t>IP-Port-Int-Port TLV is included as part of the
IP-Port-Forwarding-Map Attribute (refer to <xref
target="portmap"></xref>).</t>
<t>IP-Port-Int-Port TLV is embedded within embedded within
IP-Port-Type TLV (refer to <xref target="sessiontype"></xref>) for
detail.</t>
<figure anchor="tlv5">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV5-Type | TLV5-Length | IP-Port-Int-Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>TLV5-Type:<list counter="1" hangIndent="5">
<t>TBA6: The type field for IP-Port-Int-Port TLV.</t>
</list></t>
<t>TLV5-Length:<list counter="1" hangIndent="5">
<t>4 bytes. The Length field for IP-Port-Int-Port TLV.</t>
</list></t>
<t>IP-Port-Int-Port:<list counter="1" hangIndent="5">
<t>2 byte integer. The internal IP port number that is
associated with an IPv4 or IPv6 address.</t>
</list></t>
</section>
<section anchor="TLV6" title="IP-Port-Ext-Port TLV">
<t>This TLV (<xref target="tlv6"></xref>) uses format defined in
<xref target="RFC6929"> </xref>. Its Value field contains an
external IP port number that is associated with an external IPv4
address.</t>
<t>IP-Port-Ext-Port TLV is included as part of the
IP-Port-Forwarding-Map Attribute (refer to <xref
target="portmap"></xref>).</t>
<t>IP-Port-Ext-Port TLV is embedded within IP-Port-Type TLV (refer
to <xref target="sessiontype"></xref>) for detail.</t>
<figure anchor="tlv6">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV6-Type | TLV6-Length | IP-Port-Ext-Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>TLV6-Type:<list counter="1" hangIndent="5">
<t>TBA7: The type field for IP-Port-Ext-Port TLV.</t>
</list></t>
<t>TLV6-Length:<list counter="1" hangIndent="5">
<t>4 bytes. The Length field for IP-Port-Ext-Port TLV.</t>
</list></t>
<t>IP-Port-Ext-Port:<list counter="1" hangIndent="5">
<t>2 byte integer. The external IP port number that is
associated with an IPv4 address.</t>
</list></t>
</section>
<section anchor="TLV7" title="IP-Port-Alloc TLV">
<t>This TLV (<xref target="tlv7"></xref>) uses format defined in
<xref target="RFC6929"> </xref>. Its Value field contains a 2-byte
integer called IP-Port-Alloc, which indicates either the allocation
or deallocation of a range of IP ports.</t>
<t>IP-Port-Alloc TLV is included as part of the IP-Port-Range
Attribute (refer to <xref target="sessionrange"></xref>).</t>
<t>Note that IP-Port-Alloc TLV is embedded within IP-Port-Type TLV
(refer to <xref target="sessiontype"></xref>) for detail.</t>
<figure anchor="tlv7">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV7-Type | TLV7-Length | IP-Port-Alloc |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>TLV7-Type:<list counter="1" hangIndent="5">
<t>TBA8: The type field for IP-Port-Alloc TLV.</t>
</list></t>
<t>TLV7-Length:<list counter="1" hangIndent="5">
<t>4. The Length field for IP-Port-Alloc TLV.</t>
</list></t>
<t>IP-Port-Alloc:<list counter="1" hangIndent="5">
<t>2-byte integer. This field indicates the allocation or
deallocation of a range of IP ports as follows:</t>
<t>0:<list counter="1" hangIndent="5">
<t>Allocation</t>
</list></t>
<t>1:<list counter="1" hangIndent="5">
<t>Deallocation</t>
</list></t>
</list></t>
</section>
<section anchor="TLV8" title="IP-Port-Range-Start TLV">
<t>This TLV (<xref target="tlv8"></xref>) uses format defined in
<xref target="RFC6929"> </xref>. Its Value field contains a 2-byte
integer called IP-Port-Range-Start, which indicates the smallest
port number of a range of contiguous IP ports.</t>
<t>IP-Port-Range-Start TLV is included as part of the IP-Port-Range
Attribute (refer to <xref target="sessionrange"></xref>).</t>
<t>Note that IP-Port-Range-Start TLV is embedded within IP-Port-Type
TLV (refer to <xref target="sessiontype"></xref>) for detail.</t>
<figure anchor="tlv8">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV8-Type | TLV8-Length | IP-Port-Range-Start |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>TLV8-Type:<list counter="1" hangIndent="5">
<t>TBA9: The type field for IP-Port-Range-Start TLV.</t>
</list></t>
<t>TLV8-Length:<list counter="1" hangIndent="5">
<t>4. The Length field for IP-Port-Range-Start TLV.</t>
</list></t>
<t>IP-Port-Range-Start:<list counter="1" hangIndent="5">
<t>2-byte integer. This field contains the smallest port number
of a range of contiguous IP ports.</t>
</list></t>
</section>
<section anchor="TLV9" title="IP-Port-Range-End TLV">
<t>This TLV (<xref target="tlv9"></xref>) uses format defined in
<xref target="RFC6929"> </xref>. Its Value field contains a 2-byte
integer called IP-Port-Range-End, which indicates largest port
number of a range of contiguous IP ports.</t>
<t>IP-Port-Range-End TLV is included as part of the IP-Port-Range
Attribute (refer to <xref target="sessionrange"></xref>).</t>
<t>Note that IP-Port-Range-End TLV is embedded within IP-Port-Type
TLV (refer to <xref target="sessiontype"></xref>) for detail.</t>
<figure anchor="tlv9">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV9-Type | TLV9-Length | IP-Port-Range-End |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>TLV9-Type:<list counter="1" hangIndent="5">
<t>TBA10: The type field for IP-Port-Range-End TLV.</t>
</list></t>
<t>TLV9-Length:<list counter="1" hangIndent="5">
<t>4. The Length field for IP-Port-Range-End TLV.</t>
</list></t>
<t>IP-Port-Range-End:<list counter="1" hangIndent="5">
<t>2-byte integer. This field contains the largest port number
of a range of contiguous IP ports.</t>
</list></t>
</section>
<section anchor="TLV10" title="IP-Port-Local-Id TLV">
<t>This TLV (<xref target="tlv10"></xref>) uses format defined in
<xref target="RFC6929"> </xref>. Its Value field contains an
identifier with local significance.</t>
<t>In some CGN deployment scenarios as described such as L2NAT <xref
target="I-D.miles-behave-l2nat"></xref>, DS-Extra-Lite <xref
target="RFC6619"></xref> and Lightweight 4over6 <xref
target="I-D.ietf-softwire-lw4over6"></xref>, parameters at a
customer premise such as MAC address, interface ID, VLAN ID, PPP
session ID, IPv6 prefix, VRF ID, etc., may also be required to pass
to the RADIUS server as part of the accounting record.</t>
<t>IP-Port-Local-Id TLV can be included as part of the IP-Port-Range
Attribute (refer to <xref target="sessionrange"></xref>) and
IP-Port-Forwarding-Map Attribute (refer to <xref
target="portmap"></xref>).</t>
<t>Note that IP-Port-Local-Id TLV is embedded within IP-Port-Type
TLV (refer to <xref target="sessiontype"></xref>) for detail.</t>
<figure anchor="tlv10">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV10-Type | TLV10-Length | IP-Port-Local-Id...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
<postamble></postamble>
</figure>
<t>TLV10-Type:<list counter="1" hangIndent="5">
<t>TBA11: The type field for IP-Port-Local-Id TLV.</t>
</list></t>
<t>TLV10-Length:<list counter="1" hangIndent="5">
<t>Variable number of bytes. The Length field for
IP-Port-Local-Id TLV.</t>
</list></t>
<t>IP-Port-Local-Id:<list counter="1" hangIndent="5">
<t>This is a local session identifier at the customer premise,
such as MAC address, interface ID, VLAN ID, PPP sessions ID, VRF
ID, IPv6 address/prefix, etc. The length of this field is the
value contained in TLV7-Length field minus 2.</t>
</list></t>
</section>
</section>
</section>
<section title="Applications, Use Cases and Examples">
<t>This section describes some applications and use cases to illustrate
the use of the attributes proposed in this document.</t>
<section title="Managing CGN Port Behavior using RADIUS">
<t>In a broadband network, customer information is usually stored on a
RADIUS server, and the BNG hosts the NAS. The communication between
the NAS and the RADIUS server is triggered by a subscriber when the
user signs in to the Internet service, where either PPP or DHCP/DHCPv6
is used. When a user signs in, the NAS sends a RADIUS Access-Request
message to the RADIUS server. The RADIUS server validates the request,
and if the validation succeeds, it in turn sends back a RADIUS
Access-Accept message. The Access-Accept message carries configuration
information specific to that user, back to the NAS, where some of the
information would pass on to the requesting user via PPP or
DHCP/DHCPv6.</t>
<t>A CGN function in a broadband network would most likely reside on a
BNG. In that case, parameters for CGN port/identifier mapping behavior
for users can be configured on the RADIUS server. When a user signs in
to the Internet service, the associated parameters can be conveyed to
the NAS, and proper configuration is accomplished on the CGN device
for that user.</t>
<t>Also, CGN operation status such as CGN port/identifier allocation
and de-allocation for a specific user on the BNG can also be
transmitted back to the RADIUS server for accounting purpose using the
RADIUS protocol.</t>
<t>RADIUS protocol has already been widely deployed in broadband
networks to manage BNG, thus the functionality described in this
specification introduces little overhead to the existing network
operation.</t>
<t>In the following sub-sections, we describe how to manage CGN
behavior using RADIUS protocol, with required RADIUS extensions
proposed in <xref target="attrs"></xref>.</t>
<section title="Configure IP Port Limit for a User">
<t>In the face of IPv4 address shortage, there are currently
proposals to multiplex multiple subscribers' connections over a
smaller number of shared IPv4 addresses, such as Carrier Grade NAT
<xref target="RFC6888"></xref>, Dual-Stack Lite <xref
target="RFC6333"></xref>, NAT64 <xref target="RFC6146"></xref>, etc.
As a result, a single IPv4 public address may be shared by hundreds
or even thousands of subscribers. As indicated in <xref
target="RFC6269"></xref>, it is therefore necessary to impose limits
on the total number of ports available to an individual subscriber
to ensure that the shared resource, i.e., the IPv4 address remains
available in some capacity to all the subscribers using it, and port
limiting is also documented in <xref target="RFC6888"></xref> as a
requirement.</t>
<t>The IP port limit imposed to a specific subscriber may be on the
total number of TCP and UDP ports plus the number of ICMP
identifiers, or with other granularities as defined in <xref
target="sessionlimit"></xref>.</t>
<t>The per-subscriber based IP port limit is configured on a RADIUS
server, along with other user information such as credentials. The
value of these IP port limit is based on service agreement and its
specification is out of the scope of this document.</t>
<t>When a subscriber signs in to the Internet service successfully,
the IP port limit for the subscriber is passed to the BNG based NAS,
where CGN also locates, using a new RADIUS attribute called
IP-Port-Limit (defined in <xref target="sessionlimit"></xref>),
along with other configuration parameters. While some parameters are
passed to the subscriber, the IP port limit is recorded on the CGN
device for imposing the usage of TCP/UDP ports and ICMP identifiers
for that subscriber.</t>
<t><xref target="fig1"></xref> illustrates how RADIUS protocol is
used to configure the maximum number of TCP/UDP ports for a given
subscriber on a NAT44 device.</t>
<t><figure anchor="fig1" height=""
title="RADIUS Message Flow for Configuring NAT44 Port Limit">
<artwork><![CDATA[
User NAT44/NAS AAA
| BNG Server
| | |
| | |
|----Service Request------>| |
| | |
| |-----Access-Request -------->|
| | |
| |<----Access-Accept-----------|
| | (IP-Port-Limit) |
| | (for TCP/UDP ports) |
|<---Service Granted ------| |
| (other parameters) | |
| | |
| (NAT44 external port |
| allocation and |
| IPv4 address assignment) |
| | |
]]></artwork>
</figure></t>
<t>The IP port limit created on a CGN device for a specific user
using RADIUS extension may be changed using RADIUS CoA message <xref
target="RFC5176"></xref> that carries the same RADIUS attribute. The
CoA message may be sent from the RADIUS server directly to the NAS,
which once accepts and sends back a RADIUS CoA ACK message, the new
IP port limit replaces the previous one.</t>
<t><xref target="fig2"></xref> illustrates how RADIUS protocol is
used to increase the TCP/UDP port limit from 1024 to 2048 on a NAT44
device for a specific user.</t>
<t><figure anchor="fig2" height=""
title="RADIUS Message Flow for changing a user's NAT44 port limit">
<artwork><![CDATA[
User NAT/NAS AAA
| BNG Server
| | |
| TCP/UDP Port Limit (1024) |
| | |
| |<---------CoA Request----------|
| | (IP-Port-Limit) |
| | (for TCP/UDP ports) |
| | |
| TCP/UDP Port Limit (2048) |
| | |
| |---------CoA Response--------->|
| | |
]]></artwork>
</figure></t>
</section>
<section title="Report IP Port Allocation/De-allocation">
<t>Upon obtaining the IP port limit for a subscriber, the CGN device
needs to allocate a TCP/UDP port or an ICMP identifiers for the
subscriber when receiving a new IP flow sent from that
subscriber.</t>
<t>As one practice, a CGN may allocate a bulk of TCP/UDP ports or
ICMP identifiers once at a time for a specific user, instead of one
port/identifier at a time, and within each port bulk, the
ports/identifiers may be randomly distributed or in consecutive
fashion. When a CGN device allocates bulk of TCP/UDP ports and ICMP
identifiers, the information can be easily conveyed to the RADIUS
server by a new RADIUS attribute called the IP-Port-Range (defined
in <xref target="sessionrange"></xref>). The CGN device may allocate
one or more TCP/UDP port ranges or ICMP identifier ranges, or
generally called IP port ranges, where each range contains a set of
numbers representing TCP/UDP ports or ICMP identifiers, and the
total number of ports/identifiers must be less or equal to the
associated IP port limit imposed for that subscriber. A CGN device
may choose to allocate a small port range, and allocate more at a
later time as needed; such practice is good because its
randomization in nature.</t>
<t>At the same time, the CGN device also needs to decide the shared
IPv4 address for that subscriber. The shared IPv4 address and the
pre-allocated IP port range are both passed to the RADIUS
server.</t>
<t>When a subscriber initiates an IP flow, the CGN device randomly
selects a TCP/UDP port or ICMP identifier from the associated and
pre-allocated IP port range for that subscriber to replace the
original source TCP/UDP port or ICMP identifier, along with the
replacement of the source IP address by the shared IPv4 address.</t>
<t>A CGN device may decide to "free" a previously assigned set of
TCP/UDP ports or ICMP identifiers that have been allocated for a
specific subscriber but not currently in use, and with that, the CGN
device must send the information of the de-allocated IP port range
along with the shared IPv4 address to the RADIUS server.</t>
<t><xref target="fig3"></xref> illustrates how RADIUS protocol is
used to report a set of ports allocated and de-allocated,
respectively, by a NAT44 device for a specific user to the RADIUS
server.</t>
<t><figure anchor="fig3" height=""
title="RADIUS Message Flow for reporting NAT44 allocation/de-allocation of a port set">
<artwork><![CDATA[
Host NAT44/NAS AAA
| BNG Server
| | |
| | |
|----Service Request------>| |
| | |
| |-----Access-Request -------->|
| | |
| |<----Access-Accept-----------|
|<---Service Granted ------| |
| (other parameters) | |
... ... ...
| | |
| | |
| (NAT44 decides to allocate |
| a TCP/UDP port range for the user) |
| | |
| |-----Accounting-Request----->|
| | (IP-Port-Range |
| | for allocation) |
... ... ...
| | |
| (NAT44 decides to de-allocate |
| a TCP/UDP port range for the user) |
| | |
| |-----Accounting-Request----->|
| | (IP-Port-Range |
| | for de-allocation) |
| | |
]]></artwork>
</figure></t>
<t></t>
</section>
<section title="Configure Forwarding Port Mapping">
<t>In most scenarios, the port mapping on a NAT device is
dynamically created when the IP packets of an IP connection
initiated by a user arrives. For some applications, the port mapping
needs to be pre-defined allowing IP packets of applications from
outside a CGN device to pass through and "port forwarded" to the
correct user located behind the CGN device.</t>
<t>Port Control Protocol <xref target="RFC6887"> </xref>, provides a
mechanism to create a mapping from an external IP address and port
to an internal IP address and port on a CGN device just to achieve
the "port forwarding" purpose. PCP is a server-client protocol
capable of creating or deleting a mapping along with a rich set of
features on a CGN device in dynamic fashion. In some deployment, all
users need is a few, typically just one pre-configured port mapping
for applications such as web cam at home, and the lifetime of such a
port mapping remains valid throughout the duration of the customer's
Internet service connection time. In such an environment, it is
possible to statically configure a port mapping on the RADIUS server
for a user and let the RADIUS protocol to propagate the information
to the associated CGN device.</t>
<t><xref target="fig4"></xref> illustrates how RADIUS protocol is
used to configure a forwarding port mapping on a NAT44 device by
using RADIUS protocol.</t>
<t><figure anchor="fig4" height=""
title="RADIUS Message Flow for configuring a forwarding port mapping">
<artwork><![CDATA[
Host NAT/NAS AAA
| BNG Server
| | |
|----Service Request------>| |
| | |
| |---------Access-Request------->|
| | |
| |<--------Access-Accept---------|
| | (IP-Port-Forwarding-Map) |
|<---Service Granted ------| |
| (other parameters) | |
| | |
| (Create a port mapping |
| for the user, and |
| associate it with the |
| internal IP address |
| and external IP address) |
| | |
| | |
| |------Accounting-Request------>|
| | (IP-Port-Forwarding-Map) |
]]></artwork>
</figure></t>
<t>A port forwarding mapping that is created on a CGN device using
RADIUS extension as described above may also be changed using RADIUS
CoA message <xref target="RFC5176"></xref> that carries the same
RADIUS associate. The CoA message may be sent from the RADIUS server
directly to the NAS, which once accepts and sends back a RADIUS CoA
ACK message, the new port forwarding mapping then replaces the
previous one.</t>
<t><xref target="fig5"></xref> illustrates how RADIUS protocol is
used to change an existing port mapping from (a:X) to (a:Y), where
"a" is an internal port, and "X" and "Y" are external ports,
respectively, for a specific user with a specific IP address</t>
<t><figure anchor="fig5" height=""
title="RADIUS Message Flow for changing a user's forwarding port mapping">
<artwork><![CDATA[
Host NAT/NAS AAA
| BNG Server
| | |
| Internal IP Address |
| Port Map (a:X) |
| | |
| |<---------CoA Request----------|
| | (IP-Port-Forwarding-Map) |
| | |
| Internal IP Address |
| Port Map (a:Y) |
| | |
| |---------CoA Response--------->|
| | (IP-Port-Forwarding-Map) |
]]></artwork>
</figure></t>
</section>
<section title="An Example">
<t>An Internet Service Provider (ISP) assigns TCP/UDP 500 ports for
the subscriber Joe. This number is the limit that can be used for
TCP/UDP ports on a NAT44 device for Joe, and is configured on a
RADIUS server. Also, Joe asks for a pre-defined port forwarding
mapping on the NAT44 device for his web cam applications (external
port 5000 maps to internal port 80).</t>
<t>When Joe successfully connects to the Internet service, the
RADIUS server conveys the TCP/UDP port limit (1000) and the
forwarding port mapping (external port 5000 to internal port 80) to
the NAT44 device, using IP-Port-Limit attribute and
IP-Port-Forwarding-Map attribute, respectively, carried by an
Access-Accept message to the BNG where NAS and CGN co-located.</t>
<t>Upon receiving the first outbound IP packet sent from Joe's
laptop, the NAT44 device decides to allocate a small port pool that
contains 40 consecutive ports, from 3500 to 3540, inclusively, and
also assign a shared IPv4 address 192.0.2.15, for Joe. The NAT44
device also randomly selects one port from the allocated range (say
3519) and use that port to replace the original source port in
outbound IP packets.</t>
<t>For accounting purpose, the NAT44 device passes this port range
(3500-3540) and the shared IPv4 address 192.0.2.15 together to the
RADIUS server using IP-Port-Range attribute carried by an
Accounting-Request message.</t>
<t>When Joe works on more applications with more outbound IP
sessions and the port pool (3500-3540) is close to exhaust, the
NAT44 device allocates a second port pool (8500-8800) in a similar
fashion, and also passes the new port range (8500-8800) and IPv4
address 192.0.2.15 together to the RADIUS server using IP-Port-Range
attribute carried by an Accounting-Request message. Note when the
CGN allocates more ports, it needs to assure that the total number
of ports allocated for Joe is within the limit.</t>
<t>Joe decides to upgrade his service agreement with more TCP/UDP
ports allowed (up to 1000 ports). The ISP updates the information in
Joe's profile on the RADIUS server, which then sends a CoA-Request
message that carries the IP-Port-Limit attribute with 1000 ports to
the NAT44 device; the NAT44 device in turn sends back a CoA-ACK
message. With that, Joe enjoys more available TCP/UDP ports for his
applications.</t>
<t>When Joe travels, most of the IP sessions are closed with their
associated TCP/UDP ports released on the NAT44 device, which then
sends the relevant information back to the RADIUS server using
IP-Port-Range attribute carried by Accounting-Request message.</t>
<t>Throughout Joe's connection with his ISP Internet service,
applications can communicate with his web cam at home from external
realm directly traversing the pre-configured mapping on the CGN
device.</t>
<t>When Joe disconnects from his Internet service, the CGN device
will de-allocate all TCP/UDP ports as well as the port-forwarding
mapping, and send the relevant information to the RADIUS server.</t>
</section>
</section>
<section title="Report Assigned Port Set for a Visiting UE">
<t><xref target="wifi"></xref> illustrates an example of the flow
exchange which occurs when a visiting UE connects to a CPE offering
WLAN service.</t>
<t>For identification purposes (see <xref target="RFC6967"></xref>),
once the CPE assigns a port set, it issues a RADIUS message to report
the assigned port set.</t>
<t><figure anchor="wifi" height=""
title="RADIUS Message Flow for reporting CPE allocation/de-allocation of a port set to a visiting UE">
<artwork><![CDATA[
UE CPE NAS AAA
| BNG Server
| | |
| | |
|----Service Request------>| |
| | |
| |-----Access-Request -------->|
| | |
| |<----Access-Accept-----------|
|<---Service Granted ------| |
| (other parameters) | |
... | ... ...
|<---IP@----| | |
| | | |
| (CPE assigns a TCP/UDP port |
| range for this visiting UE) |
| | |
| |--Accounting-Request-...------------------->|
| | (IP-Port-Range |
| | for allocation) |
... | ... ...
| | | |
| | | |
| (CPE withdraws a TCP/UDP port |
| range for a visiting UE) |
| | |
| |--Accounting-Request-...------------------->|
| | (IP-Port-Range |
| | for de-allocation) |
| | |
]]></artwork>
</figure></t>
<t></t>
</section>
</section>
<section anchor="Table" title="Table of Attributes">
<t>This document proposes three new RADIUS attributes and their formats
are as follows:</t>
<t><list style="symbols">
<t>IP-Port-Limit: TBA1.TBA2.{TBA2-1..TBA2-5}.[TBA3, {TBA4}]</t>
<t>IP-Port-Range: TBA1.TBA2.{TBA2-1..TBA2-5}.[TBA8, TBA9, TBA10,
{TBA4}, {TBA11}].</t>
<t>IP-Port-Forwarding-Map: TBA1.TBA2.{TBA2-1 .. TBA2-5}.[TBA6, TBA7,
TBA5, {TBA4}]</t>
</list></t>
<t>The following table provides a guide as what type of RADIUS packets
that may contain these attributes, and in what quantity.</t>
<texttable style="none">
<ttcol>Request</ttcol>
<ttcol>Accept</ttcol>
<ttcol>Reject</ttcol>
<ttcol>Challenge</ttcol>
<ttcol>Acct. Request</ttcol>
<ttcol>#</ttcol>
<ttcol>Attribute</ttcol>
<c>0+</c>
<c>0+</c>
<c>0</c>
<c>0</c>
<c>0+</c>
<c>TBA</c>
<c>IP-Port-Limit</c>
<c>0</c>
<c>0</c>
<c>0</c>
<c>0</c>
<c>0+</c>
<c>TBA</c>
<c>IP-Port-Range</c>
<c>0+</c>
<c>0+</c>
<c>0</c>
<c>0</c>
<c>0+</c>
<c>TBA</c>
<c>IP-Port-Forwarding-Map</c>
</texttable>
<t>The following table defines the meaning of the above table
entries.</t>
<t></t>
<texttable style="none" suppress-title="true">
<ttcol></ttcol>
<ttcol></ttcol>
<c>0</c>
<c>This attribute MUST NOT be present in packet.</c>
<c>0+</c>
<c>Zero or more instances of this attribute MAY be present in
packet.</c>
<!--<c>0-1</c>
<c>Zero or one instance of this attribute MAY be present in packet.</c> -->
</texttable>
</section>
<section anchor="Security" title="Security Considerations">
<t>This document does not introduce any security issue than what has
been identified in <xref target="RFC2865"></xref>.</t>
</section>
<section anchor="IANA" title="IANA Considerations">
<t>This document requires new code point assignments for the new RADIUS
attributes as follows: <list style="symbols">
<t>TBA1 (refer to <xref target="sessiontype"></xref>): This value is
for the Radius Type field and should be allocated from the number
space of Extended-Type-1 (241), Extended-Type-2 (242),
Extended-Type-3 (243), or Extended-Type-4 (244) per <xref
target="RFC6929"></xref>.</t>
<t>TBA2 (refer to <xref target="sessiontype"></xref>): This value is
for the Extended-Type field and should be allocated from the Short
Extended Space per <xref target="RFC6929"></xref>.</t>
<t>TBA2-1, TBA2-2, TBA2-3, TBA2-4, and TBA2-5 (refer to <xref
target="sessiontype"></xref>): These values are for the Type field
of IP-Port-Type TLV that is within the TBA2 container, and they
should be allocated as TLV data type and effectively extend the
attribute tree as TBA1.TBA2.{TBA2-1, TBA2-2, TBA2-3, TBA2-4,
TBA2-5}.</t>
<t>TBA3 (refer to <xref target="sessionlimit"></xref>): This value
is for the type field of IP-Port-Limit TLV. It should be allocated
as TLV data type and it extends the attribute tree as
TBA1.TBA2.{TBA2-1, TBA2-2, TBA2-3, TBA2-4, TBA2-5}.TBA3.</t>
<t>TBA4 (refer to <xref target="TLV3"></xref>): This value is for
the Type field of IP-Port-Ext-IPv4-Addr TLV. It should be allocated
as TLV data type and it extends the attribute tree as
TBA1.TBA2.{TBA2-1, TBA2-2, TBA2-3, TBA2-4, TBA2-5}.[TBA4...].</t>
<t>TBA5 (refer to <xref target="TLV4"></xref>): This value is for
the Type field of IP-Port-Int-IP-Addr TLV. It should be allocated
as TLV data type and it extends the attribute tree as
TBA1.TBA2.{TBA2-1, TBA2-2, TBA2-3, TBA2-4, TBA2-5}.[TBA5...].</t>
<t>TBA6 (refer to <xref target="TLV5"></xref>): This value is for
the Type field of IP-Port-Int-Port TLV. It should be allocated as
TLV data type and it extends the attribute tree as
TBA1.TBA2.{TBA2-1, TBA2-2, TBA2-3, TBA2-4, TBA2-5}.[TBA6...].</t>
<t>TBA7 (refer to <xref target="TLV6"></xref>): This value is for
the Type field of IP-Port-Ext-port TLV. It should be allocated as
TLV data type and it extends the attribute tree as
TBA1.TBA2.{TBA2-1, TBA2-2, TBA2-3, TBA2-4, TBA2-5}.[TBA7...].</t>
<t>TBA8 (refer to <xref target="TLV7"></xref>): This value is for
the Type field of IP-Port-Alloc TLV. It should be allocated as TLV
data type and it extends the attribute tree as TBA1.TBA2.{TBA2-1,
TBA2-2, TBA2-3, TBA2-4, TBA2-5}.[TBA8...].</t>
<t>TBA9 (refer to <xref target="TLV8"></xref>): This value is for
the Type field of IP-Port-Range-Start TLV. It should be allocated as
TLV data type and it extends the attribute tree as
TBA1.TBA2.{TBA2-1, TBA2-2, TBA2-3, TBA2-4, TBA2-5}.[TBA9..].</t>
<t>TBA10 (refer to <xref target="TLV9"></xref>): This value is for
the Type field of IP-Port-Range-End TLV. It should be allocated as
TLV data type and it extends the attribute tree as
TBA1.TBA2.{TBA2-1, TBA2-2, TBA2-3, TBA2-4, TBA2-5}.[TBA10..].</t>
<t>TBA11 (refer to <xref target="TLV10"></xref>): This value is for
the Type field of IP-Port-Local-Id TLV. It should be allocated as
TLV data type and it extends the attribute tree as
TBA1.TBA2.{TBA2-1, TBA2-2, TBA2-3, TBA2-4, TBA2-5}.[TBA11..].</t>
</list></t>
</section>
<section title="Acknowledgements">
<t>Many thanks to Dan Wing, Roberta Maglione, Daniel Derksen, David
Thaler, Alan Dekok, Lionel Morand, and Peter Deacon for their useful
comments and suggestions.</t>
</section>
</middle>
<back>
<references title="Normative References">
&RFC2119;
&RFC1918;
&RFC2629;
&RFC2865;
&RFC5176;
<?rfc include='reference.RFC.6929'?>
</references>
<references title="Informative References">
<?rfc include='reference.RFC.3022'?>
<?rfc include='reference.RFC.6887'?>
<?rfc include='reference.RFC.6619'?>
<?rfc include='reference.I-D.ietf-softwire-lw4over6'?>
<?rfc include='reference.I-D.gundavelli-v6ops-community-wifi-svcs'?>
<?rfc include='reference.RFC.6967'?>
<?rfc include='reference.RFC.6888'?>
&RFC6146;
&RFC6269;
&RFC6333;
&I-D.miles-behave-l2nat;
</references>
</back>
</rfc>
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