Network Working GroupInternet Engineering Task Force (IETF) D. ChengInternet-DraftRequest for Comments: 8045 HuaweiIntended status:Category: Standards Track J. KorhonenExpires: May 18, 2017ISSN: 2070-1721 Broadcom Corporation M. Boucadair Orange S. Sivakumar Cisco SystemsNovember 14, 2016January 2017 RADIUS Extensions for IP Port Configuration and Reportingdraft-ietf-radext-ip-port-radius-ext-17Abstract This document defines three new RADIUS attributes. For devices that implement IP port ranges, these attributes are used to communicate with a RADIUS server in order to configure and report IP transportports,ports as well as mapping behavior for specific hosts. This mechanism can be used in various deployment scenarios such as Carrier-Grade NAT, IPv4/IPv6 translators, Provider WLANGateway,gateway, etc. This document defines a mapping between some RADIUS attributes andIPFIXIP Flow Information Export (IPFIX) Information ElementIdentifiers. Requirements Language 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 RFC 2119 [RFC2119].identifiers. Status of This Memo ThisInternet-Draftissubmitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documentsan Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF).Note that other groups may also distribute working documents as Internet-Drafts. The listIt represents the consensus ofcurrent Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents validthe IETF community. It has received public review and has been approved fora maximumpublication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 ofsix monthsRFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may beupdated, replaced, or obsoleted by other documentsobtained atany time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on May 18, 2017.http://www.rfc-editor.org/info/rfc8045. Copyright Notice Copyright (c)20162017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . 3....................................................4 2. Terminology. . . . . . . . . . . . . . . . . . . . . . . . . 4.....................................................5 2.1. Requirements Language ......................................6 3. Extensions of RADIUS Attributes and TLVs. . . . . . . . . . 5........................7 3.1. Extended Attributes for IP Ports. . . . . . . . . . . . 6...........................7 3.1.1. IP-Port-Limit-Info Attribute. . . . . . . . . . . . 6........................7 3.1.2. IP-Port-Range Attribute. . . . . . . . . . . . . . . 8.............................9 3.1.3. IP-Port-Forwarding-Map Attribute. . . . . . . . . . 11...................12 3.2. RADIUS TLVs for IP Ports. . . . . . . . . . . . . . . . 13..................................15 3.2.1. IP-Port-Type TLV. . . . . . . . . . . . . . . . . . 14...................................16 3.2.2. IP-Port-Limit TLV. . . . . . . . . . . . . . . . . . 15..................................17 3.2.3. IP-Port-Ext-IPv4-Addr TLV. . . . . . . . . . . . . . 16..........................18 3.2.4. IP-Port-Int-IPv4-Addr TLV. . . . . . . . . . . . . . 16..........................19 3.2.5. IP-Port-Int-IPv6-Addr TLV. . . . . . . . . . . . . . 17..........................20 3.2.6. IP-Port-Int-Port TLV. . . . . . . . . . . . . . . . 18...............................21 3.2.7. IP-Port-Ext-Port TLV. . . . . . . . . . . . . . . . 19...............................22 3.2.8. IP-Port-Alloc TLV. . . . . . . . . . . . . . . . . . 20..................................23 3.2.9. IP-Port-Range-Start TLV. . . . . . . . . . . . . . . 21............................24 3.2.10. IP-Port-Range-End TLV. . . . . . . . . . . . . . . . 22.............................25 3.2.11. IP-Port-Local-Id TLV. . . . . . . . . . . . . . . . 22..............................25 4. Applications, UseCasesCases, and Examples. . . . . . . . . . . . 24..........................27 4.1. Managing CGN Port BehaviorusingUsing RADIUS. . . . . . . . . 24...................27 4.1.1. Configure IP Port Limit for a User. . . . . . . . . 24.................27 4.1.2. Report IP Port Allocation/Deallocation. . . . . . . 26.............29 4.1.3. ConfigureForwardingPort Forwarding Mapping. . . . . . . . . . 28..................31 4.1.4. An Example. . . . . . . . . . . . . . . . . . . . . 30.........................................33 4.2. Report Assigned Port Set for a Visiting UE. . . . . . . 31................35 5. Table of Attributes. . . . . . . . . . . . . . . . . . . . . 32............................................36 6. Security Considerations. . . . . . . . . . . . . . . . . . . 33........................................36 7. IANA Considerations. . . . . . . . . . . . . . . . . . . . . 34............................................37 7.1.IANA Considerations onNew IPFIX Information Elements. . . . . . . . . . . . . . . . . . . . . . . . 34............................37 7.2.IANA Considerations onNew RADIUS Attributes. . . . . . 34.....................................38 7.3.IANA Considerations onNew RADIUS TLVs. . . . . . . . . 35...........................................38 8.Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 35 9.References. . . . . . . . . . . . . . . . . . . . . . . . . 36 9.1......................................................39 8.1. Normative References. . . . . . . . . . . . . . . . . . 36 9.2.......................................39 8.2. Informative References. . . . . . . . . . . . . . . . . 37....................................40 Acknowledgments ...................................................43 Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . . 39................................................43 1. Introduction In a broadband network, customer information is usually stored on a RADIUS server [RFC2865]. At the time when a user initiates an IP connection request, if this request is authorized, the RADIUS server will populate the user's configuration information to the Network Access Server (NAS), which is often referred to as a Broadband Network Gateway (BNG) in broadband access networks. The Carrier- Grade NAT (CGN) function may also be implemented on the BNG. Within this document, the CGN may performNAT44Network Address Translation from IPv4 Clients to IPv4 Servers (NAT44) [RFC3022],NAT64NAT from IPv6 Clients to IPv4 Servers (NAT64) [RFC6146], or Dual-Stack LiteAFTRAddress Family Transition Router (AFTR) [RFC6333] function. In such case, the CGN IP transport port (e.g., TCP/UDP port)mapping(s) behavior(s)mapping behaviors can be part of the configuration information sent from the RADIUS server to the NAS/BNG.TheAs part of the accounting information sent from the NAS/BNG to a RADIUS server, the NAS/BNG may also reportto the RADIUS Serverthe IP port mapping behavior applied by the CGN to a usersession to the RADIUS server, as part of the accounting information sent from the NAS/BNG to a RADIUS server.session. When IP packets traverse the CGN, it performs mapping on the IP transport (e.g., TCP/UDP) source port as required. An IP transport source port, along with a source IP address, destination IP address, destinationportport, and protocolidentifieridentifier, if applicable, uniquely identify a mapping. Since the number space of IP transport ports in the CGN's external realm is shared among multiple users assigned with the same IPv4 address, the total number of a user's simultaneous IP mappings is likely to be subject to a port quota (see Section 5 of [RFC6269]). The attributes defined in this document may also be used to report the assigned port range in somedeploymentsdeployments, such as Provider WLAN[I-D.gundavelli-v6ops-community-wifi-svcs].[WIFI-SERVICES]. For example, a visiting host can be managed bya CPE (CustomerCustomer Premises Equipment)(CPE), which will need to report the assigned port range to the service platform. This is required for identification purposes (see TR-146 [TR-146] for more details). This document proposes three new attributes as RADIUSprotocol's extensions, andprotocol extensions; they are used for separatepurposespurposes, as follows: 1. IP-Port-Limit-Info: This attribute may be carried in a RADIUS Access-Accept, Access-Request,Accounting-RequestAccounting-Request, or CoA-Request packet. The purpose of this attribute is to limit the total number of IP source transport ports allocated to auser,user and associated with one or more IPv4 or IPv6 addresses. 2. IP-Port-Range: This attribute may be carried in a RADIUS Accounting-Request packet. The purpose of this attribute is for anaddress sharingaddress-sharing device (e.g., a CGN) to report to the RADIUS server the range of IP source transport ports that have been allocated or deallocated for a user. The port range is bound to an external IPv4 address. 3. IP-Port-Forwarding-Map: This attribute may be carried in RADIUS Access-Accept, Access-Request,Accounting-RequestAccounting-Request, or CoA-Request packet. The purpose of this attribute is to specify how an IP internal source transportportport, together with its internal IPv4 or IPv6addressaddress, are mapped to an external source transport port along with the external IPv4 address. IPFIX Information Elements [RFC7012] can be used for IP flow identification and representation over RADIUS. This document provides a mapping between some RADIUS TLVs and IPFIX Information ElementIdentifiers.identifiers. A new IPFIX Information Element is defined by this document (see Section 3.2.2). IP protocol numbers (refer to [ProtocolNumbers]) can be used for identification of IP transport protocols (e.g., TCP[RFC0793],[RFC793], UDP[RFC0768], DCCP[RFC768], Datagram Congestion Control Protocol (DCCP) [RFC4340], andSCTPStream Control Transmission Protocol (SCTP) [RFC4960]) that are associated with some RADIUS attributes. This document focuses on IPv4 address sharing. Mechanisms for IPv6 prefix sharingmechanisms(e.g.,NPTv6)IPv6-to-IPv6 Network Prefix Translation (NPTv6)) are out of scope. 2. Terminology This document makes use of the following terms: o IP Port: This refers to an IP transport port (e.g., a TCP portnumber,number or UDP port number). o IP Port Type: This refers to the IP transport protocol as indicated by the IP transport protocolnumber, refer to (refernumber. Refer to[ProtocolNumbers])[ProtocolNumbers]. o IP Port Limit: This denotes the maximum number of IP ports for a specific (or all) IP transportprotocol(s),protocol(s) that a device supporting port ranges can use when performing port number mappings for a specific user/host.Note,Note that this limit is usually associated with one or more IPv4/IPv6 addresses. o IP Port Range: This specifies a set of contiguous IPports,ports indicated by the lowest numerical number and the highest numerical number, inclusively. o Internal IP Address: This refers to the IP address that is used by a host as a source IP address in an outbound IP packet sent towards a device supporting port ranges in the internal realm. The internal IP address may be IPv4 or IPv6. o External IP Address: This 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. This document assumes that the external IP address is an IPv4 address. o Internal Port: This is an IP transportport, whichport that is allocated by a host or application behind anaddress sharingaddress-sharing device for an outbound IP packet in the internal realm. o External Port: This is an IP transportport, whichport that is allocated by anaddress sharingaddress-sharing device upon receiving an outbound IP packet in the internalrealm,realm and is used to replace the internal port that is allocated by a user or application. o Externalrealm:Realm: This refers to the networking segment where external IP addresses are used as source addresses of outbound packets forwarded by anaddress sharingaddress-sharing device. o Internalrealm:Realm: This refers to the networking segment that is behind anaddress sharingaddress-sharing device and where internal IP addresses are used. o Mapping: This denotes a relationship between an internal IP address, internalportport, andtheprotocol,andas well as an external IP address, external port, andtheprotocol. oAddress sharing device:Address-Sharing Device: This is a device that is capable of sharing an IPv4 address among multiple users. A typical example of this device is a CGN, CPE, Provider WLANGateway,gateway, etc. 2.1. Requirements Language 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 RFC 2119 [RFC2119]. 3. Extensions of RADIUS Attributes and TLVs These three new attributes are defined in the followingsub-sections:subsections: 1. IP-Port-Limit-Info Attribute 2. IP-Port-Range Attribute 3. IP-Port-Forwarding-Map Attribute All these attributes are allocated from the RADIUS "Extended Type" code space per [RFC6929]. These attributes and their embedded TLVs (refer to Section 3.2) are defined with globally unique names and follow theguidelineguidelines in Section 2.7.1 of [RFC6929]. In all the figures describing the RADIUS attributes and TLV formats in the followingsub-sections,subsections, the fields are transmitted from left to right. 3.1. Extended Attributes for IP Ports 3.1.1. IP-Port-Limit-Info Attribute This attribute is of type"TLV""tlv" as defined in the RADIUS Protocol Extensions [RFC6929]. It contains somesub-attributessub-attributes, and therequirement isrequirements are as follows: o The IP-Port-Limit-Info Attribute MAY contain the IP-Port-Type TLV (see Section 3.2.1). o The IP-Port-Limit-Info Attribute MUST contain the IP-Port-Limit TLV (see Section 3.2.2). o The IP-Port-Limit-Info Attribute MAY contain theIP-Port-Ext- IPv4-AddrIP-Port-Ext-IPv4-Addr TLV (see Section 3.2.3). The IP-Port-Limit-Info Attribute specifies the maximum number of IPportsports, as indicated in IP-Port-Limit TLV, of a specific IP transportprotocolprotocol, as indicated in IP-Port-Type TLV, and associated with a given IPv4addressaddress, as indicated in IP-Port-Ext-IPv4-AddrTLVTLV, for an end user. Note that when IP-Port-Type TLV is not included as part of theIP- Port-Limit-InfoIP-Port-Limit-Info Attribute, the port limit applies to all IP transport protocols. Note also that when IP-Port-Ext-IPv4-Addr TLV is not included as part of the IP-Port-Limit-Info Attribute, the port limit applies to all the IPv4 addresses managed by theaddress sharingaddress-sharing device, e.g., a CGN or NAT64 device. The IP-Port-Limit-Info Attribute MAY appear in an Access-Accept packet. It MAY also appear in an Access-Request packet as a preferred maximum number of IP ports indicated by the device supporting port ranges co-located with the NAS, e.g., a CGN or NAT64. The IP-Port-Limit-Info Attribute MAY appear in a CoA-Request packet. The IP-Port-Limit-Info Attribute MAY appear in an Accounting-Request packet. The IP-Port-Limit-Info Attribute MUST NOT appear in any other RADIUS packet. The format of the IP-Port-Limit-Info Attribute is shown in Figure 1. 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 | Value ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 Type 241 Length This field indicates the total length inbytesoctets of all fields of this attribute, including the Type, Length, Extended-Type, and the entire length of the embedded TLVs. Extended-Type 5 Value This field contains a set of TLVs as follows: IP-Port-Type TLV This TLV contains a value that indicates the IP port type. Refer to Section 3.2.1. IP-Port-Limit TLV 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-Info Attribute. Refer to Section 3.2.2. This limit applies to all mappings that can be instantiated by an underlyingaddressaddress- sharing device without soliciting any external entity. In particular, this limit does not include the ports that are instructed by anAAAAuthentication, Authorization, and Accounting (AAA) server. IP-Port-Ext-IPv4-Addr TLV 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-Info Attribute. Refer to Section 3.2.3. IP-Port-Limit-Info Attribute is associated with the following identifier: 241.5. 3.1.2. IP-Port-Range Attribute This attribute is of type"TLV""tlv" as defined in the RADIUS Protocol Extensions [RFC6929]. It contains some sub-attributes and the requirement is as follows: o The IP-Port-Range Attribute MAY contain the IP-Port-Type TLV (see Section 3.2.1). o The IP-Port-Range Attribute MUST contain the IP-Port-Alloc TLV (see Section 3.2.8). o For port allocation, the IP-Port-Range Attribute MUST contain both the IP-Port-Range-Start TLV (see Section 3.2.9) and theIP-Port- Range-ENDIP-Port-Range-End TLV (see Section 3.2.10). For port deallocation, the IP-Port-Range Attribute MAY contain both of these two TLVs; if the two TLVs are not included, it implies that all ports that were previously allocated are now all deallocated. o The IP-Port-Range Attribute MAY contain the IP-Port-Ext-IPv4-Addr TLV (see Section 3.2.3). o The IP-Port-Range Attribute MAY contain the IP-Port-Local-Id TLV (see Section 3.2.11). The IP-Port-Range Attribute contains a range of contiguous IP ports. These ports are either to be allocated or deallocated depending on the Value carried by the IP-Port-Alloc TLV. If the IP-Port-Type TLV is included as part of the IP-Port-Range Attribute, then the port range is associated with the specific IP transport protocol as specified in the IP-Port-Type TLV, but otherwise it is for all IP transport protocols. If the IP-Port-Ext-IPv4-Addr TLV is included as part of theIP-Port- RangeIP-Port-Range Attribute, then the port range as specified is associated with the IPv4 address as indicated, but otherwise it is for all IPv4 addresses by theaddress sharingaddress-sharing device (e.g., a CGN device) for the end user. This attribute can be used to convey a single IP transport portnumber;number: in suchcasecase, the Value of the IP-Port-Range-Start TLV and the IP-Port-Range-End TLV, respectively, contain the same port number. The information contained in the IP-Port-Range Attribute is sent to RADIUS server. The IP-Port-Range Attribute MAY appear in an Accounting-Request packet. The IP-Port-Range Attribute MUST NOT appear in any other RADIUS packet. The format of the IP-Port-Range Attribute is shown in Figure 2. 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 | Value ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 Type 241 Length This field indicates the total length inbytesoctets of all fields of this attribute, including the Type, Length, Extended-Type, and the entire length of the embedded TLVs. Extended-Type 6 Value This field contains a set of TLVs as follows: IP-Port-Type TLV This TLV contains a value that indicates the IP port type. Refer to Section 3.2.1. IP-Port-Alloc TLV This TLV contains a flag to indicatethatthe 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 Section 3.2.8. IP-Port-Range-Start TLV 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 Section 3.2.9. IP-Port-Range-End TLV 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 Section 3.2.10. IP-Port-Ext-IPv4-Addr TLV This TLV contains the IPv4 address that is associated with the IP port range, as is collectively indicated in theIP-Port-Range- StartIP-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 Section 3.2.3. IP-Port-Local-Id TLV This TLV contains a localsessionsignificant identifier at the customer premise, such asMACthe Media Access Control (MAC) address, interface ID, VLAN ID, PPP sessions ID,VRFVPN Routing and Forwarding (VRF) ID, IP address/prefix, etc. This TLV is optionally included as part of the IP-Port-Range Attribute. Refer to Section 3.2.11. The IP-Port-RangeattributeAttribute is associated with the following identifier: 241.6. 3.1.3. IP-Port-Forwarding-Map Attribute This attribute is of type"TLV""tlv" as defined in the RADIUS Protocol Extensions [RFC6929]. It contains some sub-attributes and the requirement is as follows: o The IP-Port-Forwarding-Map Attribute MAY contain the IP-Port-Type TLV (see Section 3.2.1). o The IP-Port-Forwarding-Map Attribute MUST contain bothIP-Port- Int-PortIP-Port-Int-Port TLV (see Section 3.2.6) and the IP-Port-Ext-Port TLV (see Section 3.2.7). o If the internal realm is with an IPv4 address family, theIP-Port- Forwarding-MapIP-Port-Forwarding-Map Attribute MUST contain the IP-Port-Int-IPv4-Addr TLV (see Section 3.2.4); if the internal realm is with an IPv6 address family, the IP-Port-Forwarding-Map Attribute MUST contain the IP-Port-Int-IPv6-Addr TLV (see Section 3.2.5). o The IP-Port-Forwarding-Map Attribute MAY contain theIP-Port-Ext- IPv4-AddrIP-Port-Ext-IPv4-Addr TLV (see Section 3.2.3). o The IP-Port-Forwarding-Map Attribute MAY contain theIP-Port- Local-IdIP-Port-Local-Id TLV (see Section 3.2.11). The attribute contains a2-bytetwo-octet IP internal port number and a2-bytetwo-octet IP external port number. The internal port number is associated with an internal IPv4 or IPv6 address that MUST always be included. The external port number is associated with a specific external IPv4 address if included, but otherwise it is associated with all external IPv4 addresses for the end user. If the IP-Port-Type TLV is included as part of theIP-Port- Forwarding-MapIP-Port-Forwarding-Map Attribute, then the port mapping is associated with the specific IP transport protocol as specified in the IP-Port-Type TLV, but otherwise it is for all IP transport protocols. The IP-Port-Forwarding-Map Attribute MAY appear in an Access-Accept packet. It MAY also appear in an Access-Request packet to indicate a preferred port mapping by the device co-located with NAS.HoweverHowever, the server is not required to honor such a preference. The IP-Port-Forwarding-Map Attribute MAY appear in a CoA-Request packet. The IP-Port-Forwarding-Map Attribute MAY also appear in an Accounting-Request packet. The IP-Port-Forwarding-Map Attribute MUST NOT appear in any other RADIUS packet. The format of the IP-Port-Forwarding-Map Attribute is shown in Figure 3. 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 | Value .... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3 Type 241 Length This field indicates the total length inbytesoctets of all fields of this attribute, including the Type, Length, Extended-Type, and the entire length of the embedded TLVs. Extended-Type 7 Value This field contains a set of TLVs as follows: IP-Port-Type TLV This TLV contains a value that indicates the IP port type. Refer to Section 3.2.1. IP-Port-Int-Port TLV 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 theIP-Port- Forwarding-Map attribute.IP-Port-Forwarding-Map Attribute. Refer to Section 3.2.6. IP-Port-Ext-Port TLV 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-Mapattribute.Attribute. Refer to Section 3.2.7. IP-Port-Int-IPv4-Addr TLV This TLV contains an IPv4 address that is associated with the internal IP port number contained in the IP-Port-Int-Port TLV. For the internal realm with an IPv4 address family, this TLV MUST be included as part of the IP-Port-Forwarding-Map Attribute. Refer to Section 3.2.4. IP-Port-Int-IPv6-Addr TLV This TLV contains an IPv6 address that is associated with the internal IP port number contained in the IP-Port-Int-Port TLV. For the internal realm with an IPv6 address family, this TLV MUST be included as part of the IP-Port-Forwarding-Map Attribute. Refer to Section 3.2.5. IP-Port-Ext-IPv4-Addr TLV 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 Section 3.2.3. IP-Port-Local-Id TLV This TLV contains a localsessionsignificant identifier at the customer premise, such as MAC address, interface ID, VLAN ID, PPP sessions ID, VRF ID, IP address/prefix, etc. This TLV is optionally included as part of the IP-Port-Forwarding-Map Attribute. Refer to Section 3.2.11. The IP-Port-Forwarding-Map Attribute is associated with the following identifier: 241.7. 3.2. RADIUS TLVs for IP Ports The TLVs that are included in the three attributes (see Section 3.1) are defined in the followingsub-sections.subsections. These TLVs use the format defined in [RFC6929]. As the three attributes carry similar data, we have defined a common set of TLVswhichthat are used for all three attributes. That is, the TLVs have the same name andnumber,number when encapsulated in any one of the three parent attributes. SeeSectionSections 3.1.1,Section3.1.2, andSection3.1.3 for a list of which TLV is permitted within which parent attribute. The encoding of the Value field of these TLVs follows the recommendation of [RFC6158]. In particular, IP-Port-Type,IP-Port- Limit,IP-Port-Limit, IP-Port-Int-Port, IP-Port-Ext-Port, IP-Port-Alloc,IP-Port- Range-Start,IP-Port-Range-Start, and IP-Port-Range-End TLVs are encoded in 32 bits as per the recommendation in Appendix A.2.1 of [RFC6158]. 3.2.1. IP-Port-Type TLV The format of IP-Port-Type TLV is shown in Figure 4. This attribute carries the IP transport protocol number defined by IANA (refer to[ProtocolNumbers])[ProtocolNumbers]). 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-Type | Length | Protocol-Number +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Protocol-Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4 TLV-Type 1 Length6Six octets Protocol-Number Integer. This field contains the data (unsigned8) of the protocol number defined in [ProtocolNumbers], right justified, and the unused bits in this field MUST be set to zero. Protocols that do not use a port number (e.g., the Resource Reservation Protocol(RSVP),(RSVP) or IP Encapsulating Security Payload (ESP)) MUST NOT be included in the IP-Port-Type TLV. IP-Port-Type TLV MAY be included in the followingAttributes:attributes: o IP-Port-Limit-Info Attribute, identified as 241.5.1 (see Section3.1.1).3.1.1) o IP-Port-Range Attribute, identified as 241.6.1 (see Section3.1.2).3.1.2) o IP-Port-Forwarding-Map Attribute, identified as 241.7.1 (see Section3.1.3).3.1.3) When the IP-Port-Type TLV is included within a RADIUSAttribute,attribute, the associated attribute is applied to the IP transport protocol as indicated by the Protocol-Number only, such as TCP, UDP, SCTP, DCCP, etc. 3.2.2. IP-Port-Limit TLV The format of IP-Port-Limit TLV is shown in Figure 5. This attribute carries IPFIX Information Element"sourceTransportPortsLimit (458),458, "sourceTransportPortsLimit", which indicates the maximum number of IP transport ports as a limit for an end user to use that is associated with one or more IPv4 or IPv6 addresses. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-Type | Length | sourceTransportPortsLimit +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceTransportPortsLimit | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5 TLV-Type 2 Length6Six octets sourceTransportPortsLimit Integer. This field contains the data (unsigned16) of sourceTransportPortsLimit (458) defined in IPFIX, right justified, and the unused bits in this field MUST be set to zero. IP-Port-Limit TLV MUST be included as part of the IP-Port-Limit-Info Attribute (refer to Section 3.1.1), identified as 241.5.2. 3.2.3. IP-Port-Ext-IPv4-Addr TLV The format of IP-Port-Ext-IPv4-Addr TLV is shown in Figure 6. This attribute carries IPFIX Information Element 225, "postNATSourceIPv4Address", which is the IPv4 source address after NAT operation (refer to [IPFIX]). 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-Type | Length | postNATSourceIPv4Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ postNATSourceIPv4Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 6 TLV-Type 3 Length6Six octets postNATSourceIPv4Address Integer. This field contains the data (ipv4Address) of postNATSourceIPv4Address (225) defined in IPFIX. IP-Port-Ext-IPv4-Addr TLV MAY be included in the followingAttributes:attributes: o IP-Port-Limit-Info Attribute, identified as 241.5.3 (see Section3.1.1).3.1.1) o IP-Port-Range Attribute, identified as 241.6.3 (see Section3.1.2).3.1.2) o IP-Port-Forwarding-Mapping Attribute, identified as 241.7.3 (see Section3.1.3).3.1.3) 3.2.4. IP-Port-Int-IPv4-Addr TLV The format of IP-Port-Int-IPv4 TLV is shown in Figure 7. This attribute carries IPFIX Information Element 8, "sourceIPv4Address", which is the IPv4 source address before NAT operation (refer to [IPFIX]). 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-Type | Length | sourceIPv4Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceIPv4Address |+-+--+-+-+-+-+-+-++-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 7 TLV-Type 4 Length6Six octets sourceIPv4Address Integer. This field contains the data (ipv4Address) of sourceIPv4Address (8) defined in IPFIX. If the internal realm is with an IPv4 address family, theIP-Port-Int- IPv4-AddrIP-Port-Int-IPv4-Addr TLV MUST be included as part of the IP-Port-Forwarding-Map Attribute (refer to Section 3.1.3), identified as 241.7.4. 3.2.5. IP-Port-Int-IPv6-Addr TLV The format of IP-Port-Int-IPv6-Addr TLV is shown in Figure 8. This attribute carries IPFIX Information Element 27, "sourceIPv6Address", which is the IPv6 source address before NAT operation (refer to [IPFIX]). 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-Type | Length | sourceIPv6Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceIPv6Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceIPv6Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceIPv6Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceIPv6Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 8 TLV-Type 5 Length18Eighteen octets sourceIPv6Address IPv6 address (128 bits). This field contains the data (ipv6Address) of sourceIPv6Address (27) defined in IPFIX. If the internal realm is with an IPv6 address family, theIP-Port-Int- IPv6-AddrIP-Port-Int-IPv6-Addr TLV MUST be included as part of the IP-Port-Forwarding-Map Attribute (refer to Section 3.1.3), identified as 241.7.5. 3.2.6. IP-Port-Int-Port TLV The format of IP-Port-Int-Port TLV is shown in Figure 9. This attribute carries IPFIX Information Element 7, "sourceTransportPort", which is the source transport number associated with an internal IPv4 or IPv6 address (refer to [IPFIX]). 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-Type | Length | sourceTransportPort +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceTransportPort | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 9 TLV-Type 6 Length6Six octets sourceTransportPort Integer. This field contains the data (unsigned16) ofsourceTrasnportPortsourceTransportPort (7) defined in IPFIX, right justified, and unused bits MUST be set to zero. IP-Port-Int-Port TLV MUST be included as part of theIP-Port- Forwarding-MapIP-Port-Forwarding-Map Attribute (refer to Section 3.1.3), identified as 241.7.6. 3.2.7. IP-Port-Ext-Port TLV The format of IP-Port-Ext-Port TLV is shown in Figure 10. This attribute carries IPFIX Information Element 227, "postNAPTSourceTransportPort", which is the transport number associated with an external IPv4address(referaddress (refer to [IPFIX]). 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-Type | Length | postNAPTSourceTransportPort +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ postNAPTSourceTransportPort | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 10 TLV-Type 7 Length6Six octets postNAPTSourceTransportPort Integer. This field contains the data (unsigned16) ofpostNAPTSourceTrasnportPortpostNAPTSourceTransportPort (227) defined in IPFIX, right justified, and unused bits MUST be set to zero. IP-Port-Ext-Port TLV MUST be included as part of theIP-Port- Forwarding-MapIP-Port-Forwarding-Map Attribute (refer to Section 3.1.3), identified as 241.7.7. 3.2.8. IP-Port-Alloc TLV The format of IP-Port-Alloc TLV is shown in Figure 11. This attribute carries IPFIX Information Element 230, "natEvent", which is a flag to indicate an action of NAT operation (refer to [IPFIX]). When the value of natEvent is "1" (Create event), it means to allocate a range of transport ports; when the value is "2", it means to deallocate a range of transports ports. For the purpose of this TLV, no other value is used. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-Type | Length | natEvent +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ natEvent | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 11 TLV-Type 8 Length6Six octets natEvent Integer. This field contains the data (unsigned8) of natEvent (230) defined in IPFIX, right justified, and unused bits MUST be set to zero. It indicates the allocation or deallocation of a range of IP ports as follows: 0: Reserved 1: Allocation 2: DeallocationReserved: 0.IP-Port-Alloc TLV MUST be included as part of the IP-Port-Range Attribute (refer to Section 3.1.2), identified as 241.6.8. 3.2.9. IP-Port-Range-Start TLV The format of IP-Port-Range-Start TLV is shown in Figure 12. This attribute carries IPFIX Information Element 361, "portRangeStart", which is the smallest port number of a range of contiguous transport ports (refer to [IPFIX]). 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-Type | Length | portRangeStart +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ portRangeStart | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 12 TLV-Type 9 Length6Six octets portRangeStart Integer. This field contains the data (unsigned16) of portRangeStart (361) defined in IPFIX, right justified, and unused bits MUST be set to zero. IP-Port-Range-Start TLV is included as part of the IP-Port-Range Attribute (refer to Section 3.1.2), identified as 241.6.9. 3.2.10. IP-Port-Range-End TLV The format of IP-Port-Range-End TLV is shown in Figure 13. This attribute carries IPFIX Information Element 362, "portRangeEnd", which is the largest port number of a range of contiguous transport ports (refer to [IPFIX]). 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-Type | Length | portRangeEnd +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ portRangeEnd | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 13 TLV-Type 10 Length6Six octets portRangeEnd Integer. This field contains the data (unsigned16) of portRangeEnd (362) defined in IPFIX, right justified, and unused bits MUST be set to zero. IP-Port-Range-End TLV is included as part of the IP-Port-Range Attribute (refer to Section 3.1.2), identified as 241.6.10. 3.2.11. IP-Port-Local-Id TLV The format of IP-Port-Local-Id TLV is shown in Figure 14. This attribute carries a string called "localID", which is a local significant identifier as explained below. The primary issue addressed by this TLV is that there are CGN deployments that do not distinguish internal hosts by their internal IP addressalone,alone but use further identifiers for unique subscriber identification. For example, this is the case if a CGN supports overlapping private or shared IP address spaces(refer to(as described in [RFC1918] and [RFC6598]) for internal hosts of different subscribers. In such cases, different internal hosts are identified and mapped at the CGN by their IP address and/or another identifier, for example, the identifier of a tunnel between the CGN and the subscriber. In these scenarios (and similar ones), the internal IP address is not sufficient to demultiplex connections from internal hosts. An additional identifier needs to be present in the IP-Port-Range Attribute and IP-Port-Forwarding-Mapping Attribute in order to uniquely identify an internal host. The IP-Port-Local-Id TLV is used to carry this identifier. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-Type | Length | localID .... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 14 TLV-Type 11 Length Variable number ofbytes.octets localIDstring.String. The data type of this field is string (refer to[I-D.ietf-radext-datatypes]).[RFC8044]). This field contains the data that is a localsessionsignificant identifier at the customer premise, such as MAC address, interface ID, VLAN ID, PPP sessions ID, VRF ID, IP address/prefix, or another localsessionsignificant identifier. IP-Port-Local-Id TLV MAY be included in the following Attributes if it is necessary to identify the subscriber: o IP-Port-Range Attribute, identified as 241.6.11 (see Section3.1.2).3.1.2) o IP-Port-Forwarding-Mapping Attribute, identified as 241.7.11 (see Section3.1.3).3.1.3) 4. Applications, UseCasesCases, and Examples This section describes some applications and use cases to illustrate the use of the attributes proposed in this document. 4.1. Managing CGN Port BehaviorusingUsing RADIUS In a broadband network, customer information is usually stored on a RADIUS server, and the BNG acts as a NAS. The communication between the NAS and the RADIUS server is triggered by a user when it signs in to the Internetservice,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 RADIUSAccess- AcceptAccess-Accept message. The Access-Accept message carries configuration information specific to thatuser,user back to the NAS, where some of the information wouldpassbe passed on to the requesting user via PPP orDHCP/ DHCPv6.DHCP/DHCPv6. A CGN function in a broadband network is most likely to be co-located on a BNG. In that case, parameters for CGN port 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. Also, a CGN operation status such as CGN port allocation and deallocation for a specific user on the BNG can also be transmitted back to the RADIUS server for accountingpurposepurposes using the RADIUS protocol. The 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. In the followingsub-sections,subsections, we describe how to manage CGN behavior using the RADIUS protocol, with required RADIUS extensions proposed in Section 3. 4.1.1. Configure IP Port Limit for a User In the face of an IPv4 address shortage, there are currently proposals to multiplex multiple users' connections over a number of shared IPv4 addresses, such as Carrier Grade NAT [RFC6888], Dual-Stack Lite [RFC6333], NAT64 [RFC6146], etc. As a result, a single IPv4 public address may be shared by hundreds or even thousands of users. As indicated in [RFC6269], it is therefore necessary to impose limits on the total number of ports available to an individual user to ensure that the shared resource, i.e., the IPv4 address, remains available in some capacity to all the users using it. The support of an IP port limit is also documented in [RFC6888] as a requirement for CGN. The IP port limit imposedtoon an end user may be on the total number of IP source transportports,ports or a specific IP transport protocol as defined in Section 3.1.1. The per-userbasedIP port limit is configured on a RADIUS server, along with other user information such as credentials. When a user signs in to the Internet service successfully, the IP port limit for the subscriber is passed by the RADIUS server to the BNG, which is acting as a NAS and is co-located with theCGN,CGN using theIP-Port- Limit-InfoIP-Port-Limit-Info RADIUS attribute (defined in Section3.1.1),3.1.1) along with other configuration parameters. While some parameters are passed to the user, the IP port limit is recorded on the CGN device for imposing the usage of IP transport ports for that user. Figure 15 illustrates how the RADIUS protocol is used to configure the maximum number of TCP/UDP ports for a given user on a CGN device. User CGN/NAS AAA | BNG Server | | | | | | |----Service Request------>| | | | | | |-----Access-Request -------->| | | | | |<----Access-Accept-----------| | | (IP-Port-Limit-Info) | | | (for TCP/UDP ports) | |<---Service Granted ------| | | (other parameters) | | | | | | (CGN external port | | allocation and | | IPv4 address assignment) | | | | Figure 15: RADIUS Message Flow for Configuring CGN Port Limit The IP port limit created on a CGN device for a specific user using a RADIUS extension may be changed using a RADIUS CoA message [RFC5176] that carries the same RADIUS attribute. The CoA message may be sent from the RADIUS server directly to the NAS,which once acceptsandsends backonce a RADIUS CoA ACKmessage,message is accepted and sent back, the new IP port limit replaces the previous one. Figure 16 illustrates how the RADIUS protocol is used to increase the TCP/UDP port limit from 1024 to 2048 on a CGN device for a specific user. User CGN/NAS AAA | BNG Server | | | | TCP/UDP Port Limit (1024) | | | | | |<---------CoA Request----------| | | (IP-Port-Limit-Info) | | | (for TCP/UDP ports) | | | | | TCP/UDP Port Limit (2048) | | | | | |---------CoA Response--------->| | | | Figure 16: RADIUS Message Flow forchangingChanging auser'sUser's CGNport limitPort Limit 4.1.2. Report IP Port Allocation/Deallocation Upon obtaining the IP port limit for a user, the CGN device needs to allocate an IP transport port for the user when receiving a new IP flow sent from that user. As one practice, a CGN may allocate a block of IP ports for a specific user, instead of one port at a time, and within each portblock,block the ports may be randomly distributed or in consecutive fashion. When a CGN device allocates a block of transport ports, the information can be easily conveyed to the RADIUS server by a new RADIUS attribute called the IP-Port-Range (defined in Section 3.1.2). The CGN device may allocate one or more IP port ranges, where each range contains a set of numbers representing IP transportports,ports and the total number of ports MUST be less or equal to the associated IP port limit imposed for that user. A CGN device may choose to allocate a small portrange,range and allocate more at a later time as needed; such practice is good because of its randomization in nature. At the same time, the CGN device also needs to decide on the shared IPv4 address for that user. The shared IPv4 address and the pre-allocated IP port range are both passed to the RADIUS server. When a user initiates an IP flow, the CGN device randomly selects a transport port number from the associated and pre-allocated IP port range for that user to replace the original source portnumber,number along with the replacement of the source IP address by the shared IPv4 address. A CGN device may decide to "free" a previously assigned set of IP ports that have been allocated for a specific user but are not currently in use, and with that, the CGN device must send the information of the deallocated IP port range along with the shared IPv4 address to the RADIUS server. Figure 17 illustrates how the RADIUS protocol is used to report a set of ports allocated and deallocated, respectively, by a NAT64 device for a specific user to the RADIUS server. 2001:db8:100:200::/56 is the IPv6 prefix allocated to this user. In order to limit the usage of the NAT64 resources on a per-user basis for fairness of resource usage (see REQ-4 of [RFC6888]), port range allocations are bound to the /56 prefix, not to the source IPv6 address of the request. The NAT64devicesdevice is configured with the per-user port limit policy by some means (e.g., subscriber-mask [RFC7785]). Host NAT64/NAS AAA | BNG Server | | | | | | |----Service Request------>| | | | | | |-----Access-Request -------->| | | | | |<----Access-Accept-----------| |<---Service Granted ------| | | (other parameters) | | ... ... ... | | | | | | | (NAT64 decides to allocate | | a TCP/UDP port range for the user) | | | | | |-----Accounting-Request----->| | | (IP-Port-Range | | | for allocation) | ... ... ... | | | | (NAT64 decides to deallocate | | a TCP/UDP port range for the user) | | | | | |-----Accounting-Request----->| | | (IP-Port-Range | | | for deallocation) | | | | Figure 17: RADIUS Message Flow forreportingReporting NAT64allocation/ deallocationAllocation/Deallocation of aport setPort Set 4.1.3. ConfigureForwardingPort Forwarding Mapping 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 bepre- defined allowingpre-defined and allow IP packets of applications from outside a CGN device to pass through and be "port forwarded" to the correct user located behind the CGN device. The Port Control Protocol (PCP) [RFC6887], 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 somedeployment,deployments, all users need is afew, typicallyfew (typically justoneone) pre-configured portmappingmappings for applications at home, such as a webcam at home, andcam; 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 protocoltopropagate the information to the associated CGN device. Note that this document targets deployments where a AAA server is responsibledefor instructing NAT mappings for a given subscriber and does not make any assumption about the host's capabilities with regards to port forwarding control. This deployment is complementary to PCP given that PCP targets a different deployment model where an application (on the host) controls its mappings in an upstream CPE, CGN, firewall, etc. Figure 18 illustrates how the RADIUS protocol is used to configure aforwardingport forwarding mapping on a NAT44device by using RADIUS protocol.device. Host CGN/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) | Figure 18: RADIUS Message Flow forconfiguringConfiguring aforwarding port mappingPort Forwarding Mapping A port forwarding mapping that is created on a CGN device using the RADIUS extension as described above may also be changed using a RADIUS CoA message [RFC5176] that carries the same RADIUS association. The CoA message may be sent from the RADIUS server directly to the NAS,which once acceptsandsends back aonce the RADIUS CoA ACKmessage,message is accepted and sent back, the new port forwarding mapping then replaces the previous one. Figure 19 illustrates how the 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 Host CGN/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) | Figure 19: RADIUS Message Flow forchangingChanging auser's forwarding port mappingUser's Port Forwarding Mapping 4.1.4. An Example An Internet Service Provider (ISP) assigns TCP/UDP 500 ports for the user Joe. This number is the limit that can be used for TCP/UDP ports on a CGN device forJoe,Joe and it is configured on a RADIUS server. Also, Joe asks for a pre-defined port forwarding mapping on the CGN device for his web cam applications (external port 5000 maps to internal port 1234). When Joe successfully connects to the Internet service, the RADIUS server conveys the TCP/UDP port limit (500) and theforwardingport forwarding mapping (external port 5000 to internal port 1234) to the CGNdevice,device using the IP-Port-Limit-Info Attribute and IP-Port-Forwarding-Mapattribute,Attribute, respectively, carried by an Access-Accept message to the BNG where NAS and CGN are co-located. Upon receiving the first outbound IP packet sent from Joe's laptop, the CGN device decides to allocate a small port pool that contains 40 consecutive ports, from 3500 to 3540, inclusively, and alsoassignassigns a shared IPv4 address192.0.2.15,192.0.2.15 for Joe. The CGN device also randomly selects one port from the allocated range(say(say, 3519) anduseuses that port to replace the original source port in outbound IP packets. For accountingpurpose,purposes, the CGN device passes this port range (3500-3540) and the shared IPv4 address 192.0.2.15 together to the RADIUS server using IP-Port-RangeattributeAttribute carried by anAccounting- RequestAccounting-Request message. When Joe works on more applications with more outbound IP mappings and the port pool (3500-3540) is close to exhaust, the CGN device allocates a second port pool (8500-8800) in a similarfashion,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-RangeattributeAttribute 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. 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-Info Attribute with 1000 ports to the CGN device; the CGN device in turn sends back a CoA-ACK message. With that, Joe enjoys more available TCP/UDP ports for his applications. When Joe is not using his service, most of the IP mappings are closed with their associated TCP/UDP ports released on the CGN device, which then sends the relevant information back to the RADIUS server using the IP-Port-RangeattributeAttribute carried by the Accounting-Request message. Throughout Joe's connection with hisISP Internet service,ISP, applications can communicate with his web cam at home from the externalrealmrealm, thus directly traversing the pre-configured mapping on the CGN device. When Joe disconnects from his Internet service, the CGN device will deallocate all TCP/UDP ports as well as theport-forwarding mapping,port forwarding mapping and send the relevant information to the RADIUS server. 4.2. Report Assigned Port Set for a Visiting UE Figure 20 illustrates an example of the flow exchangewhichthat occurs whenathe visiting User Equipment (UE) connects to a CPE offering WLAN service. For identification purposes (see [RFC6967]), once the CPE assigns a port set, it issues a RADIUS message to report the assigned port set. UE CPE CGN 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 deallocation) | | | | Figure 20: RADIUS Message Flow forreportingReporting CPEallocation/ deallocationAllocation/Deallocation of aport setPort Set to avisitingVisiting UE 5. Table of Attributes This document proposes three new RADIUSattributesattributes, and their formats are as follows: o IP-Port-Limit-Info:241.5.241.5 o IP-Port-Range:241.6.241.6 o IP-Port-Forwarding-Map:241.7.241.7 The following table provides a guide as to what type of RADIUS packetsthatmay contain theseattributes,attributes and in what quantity. Request Accept Reject Challenge Acct. # Attribute Request 0+ 0+ 0 0 0+ 241.5 IP-Port-Limit-Info 0 0 0 0 0+ 241.6 IP-Port-Range 0+ 0+ 0 0 0+ 241.7 IP-Port-Forwarding-Map The following table defines the meaning of the above table entries. 0 This attribute MUST NOT be present in packet. 0+ Zero or more instances of this attribute MAY be present in packet. 6. Security Considerations This document does not introduce any security issue other than the ones already identified in RADIUS documents [RFC2865] and [RFC5176] for CoA messages. Known RADIUS vulnerabilities apply to this specification. For example, if RADIUS packets are sent in the clear, an attacker in the communication path between the RADIUS client and server may glean information that it will use to prevent a legitimate userto accessfrom accessing the service by appropriately setting the maximum number of IP ports conveyed in an IP-Port-Limit-InfoAttribute,Attribute; exhaust the port quota of a user by installing many mapping entries (IP-Port-Forwarding-MapAttribute),Attribute); prevent incoming trafficto befrom being delivered to its legitimate destination by manipulating the mapping entries installed by means of an IP-Port-Forwarding-MapAttribute,Attribute; discover the IP address and port range that are assigned to a given user andwhich isreported in an IP-Port-RangeAttribute, etc.Attribute; and so on. The root cause of these attack vectors is the communication between the RADIUS client and server. The IP-Port-Local-Id TLV includes an identifier of which the type and length is deployment and implementation dependent. This identifier might carryprivacy sensitiveprivacy-sensitive information. It is therefore RECOMMENDED to utilize identifiers that do not have such privacy concerns. If there is any error in aRadiusRADIUS Accounting-Request packet sent from a RADIUS client to the server, the RADIUS server MUST NOT send a response to the client (refer to [RFC2866]). Examples of the errors include the erroneous port range in the IP-Port-Range Attribute, inconsistent port mapping in the IP-Port-Forwarding-Map Attribute, etc. This document targets deployments where a trusted relationship is in place between the RADIUS client and server with communication optionally secured by IPsec or Transport Layer Security (TLS) [RFC6614]. 7. IANAConsiderations This document requiresConsiderations Per this document, IANA has made new code point assignments for both IPFIX Information Elements and RADIUS attributes as explained in the followingsub-sections.subsections. 7.1.IANA Considerations onNew IPFIX Information Elements The followingis a newIPFIX Information Elementas requested by this documenthas been registered (refer to Section3.2.2) :3.2.2): o sourceTransportPortsLimit: * Name:sourceTransportPortsLimit.sourceTransportPortsLimit * Element ID:458.458 * Description: This Information Element contains the maximum number of IP source transport ports that can be used by an end user when sending IP packets; each user is associated with one or more (source) IPv4 or IPv6 addresses. ThisIEInformation Element is particularly useful inaddress sharingaddress-sharing deployments that adhere to REQ-4 of [RFC6888]. Limiting the number of ports assigned to each user ensures fairness among users and mitigates the denial-of-service attack that a user could launch against other users through theaddress sharingaddress-sharing device in order to grab more ports. * Data type:unsigned16.unsigned16 * Data type semantics:totalCounter.totalCounter * Data type unit:ports.ports * Data value range: from 1 to65535.65535 7.2.IANA Considerations onNew RADIUS Attributes Theauthors request thatAttribute Typesand Attribute Valuesdefined in this documentbehave been registered bythe Internet Assigned Numbers Authority (IANA)IANA from the RADIUSnamespacesnamespace as described in the "IANA Considerations" section of [RFC3575], in accordance with BCP 26 [RFC5226]. For RADIUS packets,attributesattributes, and registries created by thisdocumentdocument, IANAis requested to placehas placed them athttp://www.iana.org/assignments/radius-types.<http://www.iana.org/assignments/radius-types>. In particular, this document defines three new RADIUS attributes,entitled "IP-Port-Limit-Info" (see Section 3.1.1), "IP-Port-Range" (see Section 3.1.2) and "IP-Port-Forwarding-Map" (see Section 3.1.3), with assigned values of 241.5, 241.6 and 241.7as follows, from the Short Extended Space of [RFC6929]: TypeName Meaning ----Description Data Type Reference ---------------------- --------- --------- 241.5 IP-Port-Limit-Infoseetlv Section 3.1.1 241.6 IP-Port-Rangeseetlv Section 3.1.2 241.7 IP-Port-Forwarding-Mapseetlv Section 3.1.3 7.3.IANA Considerations onNew RADIUS TLVs IANA has created a new registry called "RADIUS IP PortConfiguraionConfiguration and Reporting TLVs". All TLVs in this registry have one or more parentRadiusRADIUS attributes in nesting (refer to[RFC6929].[RFC6929]). Thisregistrayregistry contains the following TLVs: ValueName Definition -----Description Data Type Reference -------------------------- --------- --------- 0 Reserved 1 IP-Port-Typeseeinteger Section 3.2.1 2 IP-Port-Limitseeinteger Section 3.2.2 3 IP-Port-Ext-IPv4-Addrseeipv4addr Section 3.2.3 4 IP-Port-Int-IPv4-Addrseeipv4addr Section 3.2.4 5 IP-Port-Int-IPv6-Addrseeipv4addr Section 3.2.5 6 IP-Port-Int-Portseeinteger Section 3.2.6 7 IP-Port-Ext-Portseeinteger Section 3.2.7 8 IP-Port-Allocseeinteger Section 3.2.8 9 IP-Port-Range-Startseeinteger Section 3.2.9 10 IP-Port-Range-Endseeinteger Section 3.2.10 11 IP-Port-Local-Idseestring Section 3.2.11 12-255UnsignedUnassigned The registration procedure for this registry is Standards Action as defined in [RFC5226]. 8.Acknowledgements Many thanks to Dan Wing, Roberta Maglione, Daniel Derksen, David Thaler, Alan Dekok, Lionel Morand, and Peter Deacon for their useful comments and suggestions. Special thanks to Lionel Morand for the Shepherd review and to Kathleen Moriarty for the AD review. Thanks to Carl Wallace, Tim Chown, and Ben Campbell for the detailed review. 9.References9.1.8.1. Normative References[I-D.ietf-radext-datatypes] DeKok, A., "Data Types in the Remote Authentication Dial- In User Service Protocol (RADIUS)", draft-ietf-radext- datatypes-08 (work in progress), October 2016.[IPFIX] IANA, "IP Flow Information Export (IPFIX) Entities",<http://www.iana.org/assignments/ipfix/ipfix.xhtml>.<http://www.iana.org/assignments/ipfix/>. [ProtocolNumbers] IANA, "Protocol Numbers",<http://www.iana.org/assignments/protocol-numbers/ protocol-numbers.xhtml>.<http://www.iana.org/assignments/protocol-numbers/>. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>. [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, DOI 10.17487/RFC2865, June 2000, <http://www.rfc-editor.org/info/rfc2865>. [RFC3575] Aboba, B., "IANA Considerations for RADIUS (Remote Authentication Dial In User Service)", RFC 3575, DOI 10.17487/RFC3575, July 2003, <http://www.rfc-editor.org/info/rfc3575>. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, DOI 10.17487/RFC5226, May 2008, <http://www.rfc-editor.org/info/rfc5226>. [RFC6929] DeKok, A. and A. Lior, "Remote Authentication Dial In User Service (RADIUS) Protocol Extensions", RFC 6929, DOI 10.17487/RFC6929, April 2013, <http://www.rfc-editor.org/info/rfc6929>. [RFC7012] Claise, B.,Ed.Ed., and B. Trammell, Ed., "Information Model for IP Flow Information Export (IPFIX)", RFC 7012, DOI 10.17487/RFC7012, September 2013, <http://www.rfc-editor.org/info/rfc7012>.9.2.[RFC8044] DeKok, A., "Data Types in RADIUS", RFC 8044, DOI 10.17487/RFC8044, January 2017, <http://www.rfc-editor.org/info/rfc8044>. 8.2. Informative References[I-D.gundavelli-v6ops-community-wifi-svcs] Gundavelli, S., Grayson, M., Seite, P., and Y. Lee, "Service Provider Wi-Fi Services Over Residential Architectures", draft-gundavelli-v6ops-community-wifi- svcs-06 (work in progress), April 2013. [RFC0768][RFC768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, DOI 10.17487/RFC0768, August 1980, <http://www.rfc-editor.org/info/rfc768>.[RFC0793][RFC793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, DOI 10.17487/RFC0793, September 1981, <http://www.rfc-editor.org/info/rfc793>. [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, <http://www.rfc-editor.org/info/rfc1918>. [RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, DOI 10.17487/RFC2866, June 2000, <http://www.rfc-editor.org/info/rfc2866>. [RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network Address Translator (Traditional NAT)", RFC 3022, DOI 10.17487/RFC3022, January 2001, <http://www.rfc-editor.org/info/rfc3022>. [RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram Congestion Control Protocol (DCCP)", RFC 4340, DOI 10.17487/RFC4340, March 2006, <http://www.rfc-editor.org/info/rfc4340>. [RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol", RFC 4960, DOI 10.17487/RFC4960, September 2007, <http://www.rfc-editor.org/info/rfc4960>. [RFC5176] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B. Aboba, "Dynamic Authorization Extensions to Remote Authentication Dial In User Service (RADIUS)", RFC 5176, DOI 10.17487/RFC5176, January 2008, <http://www.rfc-editor.org/info/rfc5176>. [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146, April 2011, <http://www.rfc-editor.org/info/rfc6146>. [RFC6158] DeKok, A.,Ed.Ed., and G. Weber, "RADIUS Design Guidelines", BCP 158, RFC 6158, DOI 10.17487/RFC6158, March 2011, <http://www.rfc-editor.org/info/rfc6158>. [RFC6269] Ford, M., Ed., Boucadair, M., Durand, A., Levis, P., and P. Roberts, "Issues with IP Address Sharing", RFC 6269, DOI 10.17487/RFC6269, June 2011, <http://www.rfc-editor.org/info/rfc6269>. [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee,"Dual- Stack"Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011, <http://www.rfc-editor.org/info/rfc6333>. [RFC6598] Weil, J., Kuarsingh, V., Donley, C., Liljenstolpe, C., and M. Azinger, "IANA-Reserved IPv4 Prefix for Shared Address Space", BCP 153, RFC 6598, DOI 10.17487/RFC6598, April 2012, <http://www.rfc-editor.org/info/rfc6598>. [RFC6614] Winter, S., McCauley, M., Venaas, S., and K. Wierenga, "Transport Layer Security (TLS) Encryption for RADIUS", RFC 6614, DOI 10.17487/RFC6614, May 2012, <http://www.rfc-editor.org/info/rfc6614>. [RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and P. Selkirk, "Port Control Protocol (PCP)", RFC 6887, DOI 10.17487/RFC6887, April 2013, <http://www.rfc-editor.org/info/rfc6887>. [RFC6888] Perreault, S., Ed., Yamagata, I., Miyakawa, S., Nakagawa, A., and H. Ashida, "Common Requirements for Carrier-Grade NATs (CGNs)", BCP 127, RFC 6888, DOI 10.17487/RFC6888, April 2013, <http://www.rfc-editor.org/info/rfc6888>. [RFC6967] Boucadair, M., Touch, J., Levis, P., and R. Penno, "Analysis of Potential Solutions for Revealing a Host Identifier (HOST_ID) in Shared Address Deployments", RFC 6967, DOI 10.17487/RFC6967, June 2013, <http://www.rfc-editor.org/info/rfc6967>. [RFC7785] Vinapamula, S. and M. Boucadair, "Recommendations for Prefix Binding in the Context of Softwire Dual-Stack Lite", RFC 7785, DOI 10.17487/RFC7785, February 2016, <http://www.rfc-editor.org/info/rfc7785>. [TR-146] Broadband Forum, "TR-146: Subscriber Sessions",<http://www.broadband-forum.org/technical/download/ TR-146.pdf>.Broadband Forum Technical Report 146, Issue 1, May 2013, <http://www.broadband-forum.org/technical/ download/TR-146.pdf>. [WIFI-SERVICES] Gundavelli, S., Grayson, M., Seite, P., and Y. Lee, "Service Provider Wi-Fi Services Over Residential Architectures", Work in Progress, draft-gundavelli-v6ops-community-wifi-svcs-06, April 2013. Acknowledgments Many thanks to Dan Wing, Roberta Maglione, Daniel Derksen, David Thaler, Alan DeKok, Lionel Morand, and Peter Deacon for their useful comments and suggestions. Special thanks to Lionel Morand for the Shepherd review and to Kathleen Moriarty for the AD review. Thanks to Carl Wallace, Tim Chown, and Ben Campbell for the detailed review. Authors' Addresses Dean Cheng Huawei 2330 Central Expressway Santa Clara, California 95050USAUnited States of America Email: dean.cheng@huawei.com Jouni Korhonen Broadcom Corporation 3151 Zanker Road San Jose 95134USAUnited States of America Email: jouni.nospam@gmail.com Mohamed Boucadair Orange Rennes France Email: mohamed.boucadair@orange.com Senthil Sivakumar Cisco Systems 7100-8 Kit Creek Road Research Triangle Park, North CarolinaUSAUnited States of America Email: ssenthil@cisco.com