Network Working Group D. Cheng Internet-Draft Huawei Intended status: Standards Track J. Korhonen Expires: April 21, 2016 Broadcom Corporation M. Boucadair France Telecom S. Sivakumar Cisco Systems October 19, 2015 RADIUS Extensions for IP Port Configuration and Reporting draft-ietf-radext-ip-port-radius-ext-06 Abstract 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. 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]. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any 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 April 21, 2016. Cheng, et al. Expires April 21, 2016 [Page 1] Internet-Draft RADIUS Extensions for IP Port October 2015 Copyright Notice Copyright (c) 2015 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 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Extensions of RADIUS Attributes and TLVs . . . . . . . . . . 5 3.1. Extended Attributes for IP Ports . . . . . . . . . . . . 6 3.1.1. IP-Port-Limit Attribute . . . . . . . . . . . . . . . 6 3.1.2. IP-Port-Range Attribute . . . . . . . . . . . . . . . 7 3.1.3. IP-Port-Forwarding-Map Attribute . . . . . . . . . . 10 3.2. RADIUS TLVs for IP Ports . . . . . . . . . . . . . . . . 12 3.2.1. IP-Port-Type TLV . . . . . . . . . . . . . . . . . . 12 3.2.2. IP-Port-Limit TLV . . . . . . . . . . . . . . . . . . 13 3.2.3. IP-Port-Ext-IPv4-Addr TLV . . . . . . . . . . . . . . 14 3.2.4. IP-Port-Int-IPv4-Addr TLV . . . . . . . . . . . . . . 15 3.2.5. IP-Port-Int-IPv6-Addr TLV . . . . . . . . . . . . . . 16 3.2.6. IP-Port-Int-Port TLV . . . . . . . . . . . . . . . . 16 3.2.7. IP-Port-Ext-Port TLV . . . . . . . . . . . . . . . . 17 3.2.8. IP-Port-Alloc TLV . . . . . . . . . . . . . . . . . . 18 3.2.9. IP-Port-Range-Start TLV . . . . . . . . . . . . . . . 19 3.2.10. IP-Port-Range-End TLV . . . . . . . . . . . . . . . . 20 3.2.11. IP-Port-Local-Id TLV . . . . . . . . . . . . . . . . 21 4. Applications, Use Cases and Examples . . . . . . . . . . . . 22 4.1. Managing CGN Port Behavior using RADIUS . . . . . . . . . 22 4.1.1. Configure IP Port Limit for a User . . . . . . . . . 23 4.1.2. Report IP Port Allocation/De-allocation . . . . . . . 25 4.1.3. Configure Forwarding Port Mapping . . . . . . . . . . 26 4.1.4. An Example . . . . . . . . . . . . . . . . . . . . . 28 4.2. Report Assigned Port Set for a Visiting UE . . . . . . . 29 5. Table of Attributes . . . . . . . . . . . . . . . . . . . . . 30 6. Security Considerations . . . . . . . . . . . . . . . . . . . 31 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31 7.1. IANA Considerations on New IPFIX Elements . . . . . . . . 31 7.2. IANA Considerations on New RADIUS Attributes . . . . . . 32 Cheng, et al. Expires April 21, 2016 [Page 2] Internet-Draft RADIUS Extensions for IP Port October 2015 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 33 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 33 9.1. Normative References . . . . . . . . . . . . . . . . . . 33 9.2. Informative References . . . . . . . . . . . . . . . . . 34 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35 1. Introduction In a broadband network, customer information is usually stored on a RADIUS server [RFC2865] 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 the CGN TCP/UDP port (or ICMP identifier) mapping(s) behavior(s) 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. The CGN device that communicates with a RADIUS server using RADIUS extensions defined in this document may perform NAT44 [RFC3022], NAT64 [RFC6146], or Dual-Stack Lite AFTR [RFC6333] function. 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 [RFC6269]). The attributes defined in this document may also be used to report the assigned port range in some deployments such as Provider WLAN [I-D.gundavelli-v6ops-community-wifi-svcs]. 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 TR-146 [TR-146] for example). This document proposes three new attributes as RADIUS protocol's extensions, and they are used for separate purposes as follows: Cheng, et al. Expires April 21, 2016 [Page 3] Internet-Draft RADIUS Extensions for IP Port October 2015 1. 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 one or more IPv4 addresses. 2. 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. 3. 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. This document leverages the protocol defined in [RFC7012] by proposing a mapping between type field of RADIUS TLV and Element ID of IPFIX. It also proposes a few new IPFIX Elements as required by this document (see Section 3). This document was constructed using the [RFC2629]. 2. Terminology This document makes use if the following terms: o IP Port: refers to the port numbers of IP transport protocols, including TCP port, UDP port and ICMP identifier. o 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. o IP Port Limit: denotes the maximum number of IP ports for a specific IP port type, that a device supporting port ranges can use when performing port number mapping for a specific user. Note, this limit is usually associated with one or more IPv4 addresses. o IP Port Range: specifies a set of contiguous IP ports, indicated by the smallest numerical number and the largest numerical number, inclusively. Cheng, et al. Expires April 21, 2016 [Page 4] Internet-Draft RADIUS Extensions for IP Port October 2015 o 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 [RFC1918]. o 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. o 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. o 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. o External realm: refers to the networking segment where IPv4 public addresses are used in respective of the device supporting port ranges. o Internal realm: refers to the networking segment that is behind a device supporting port ranges and where IPv4 private addresses are used. o 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. o 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. 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 [RFC6887], and [RFC6888]. 3. Extensions of RADIUS Attributes and TLVs These three new attributes are defined in the following sub-sections: 1. IP-Port-Limit Attribute Cheng, et al. Expires April 21, 2016 [Page 5] Internet-Draft RADIUS Extensions for IP Port October 2015 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]. 3.1. Extended Attributes for IP Ports 3.1.1. IP-Port-Limit Attribute This attribute is RADIUS Extended-Type, and contains a set of embedded TLVs defined in Section 3.2.1 (IP-Port-Type TLV), Section 3.2.2 (IP-Port-Limit TLV), and Section 3.2.3 (IP-Port-Ext- IPv4-Addr TLV). It specifies the maximum number of IP ports as indicated in IP-Port-Limit TLV, of a specific port type as indicated in IP-Port-Type TLV, 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. 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. The IP-Port-Limit Attribute MAY appear in a CoA-Request packet. The IP-Port-Limit Attribute MAY appear in an Accounting-Request packet. The IP-Port-Limit Attribute MUST NOT appear in any other RADIUS packets. The format of the IP-Port-Limit Attribute is shown in Figure 1. The fields are transmitted from left to right. 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 Cheng, et al. Expires April 21, 2016 [Page 6] Internet-Draft RADIUS Extensions for IP Port October 2015 Type: TBA1. Length: 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. Extended-Type: TBA2. 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 Attribute. Refer to Section 3.2.2. 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 Attribute. Refer to Section 3.2.3. IP-Port-Limit attribute is associated with the following identifier: Type(TBA1).Extended-Type(TBA2).[IP-Port-Limit TLV (TBA6),IP-Port-Type TLV(TBA5), {IP-Port-Ext-IPv4-Addr TLV(TBA7)}]. 3.1.2. IP-Port-Range Attribute This attribute is RADIUS Extended-Type, and contains a set of embedded TLVs defined in Section 3.2.1(IP-Port-Type TLV), Section 3.2.9(IP-Port-Range-Start TLV), Section 3.2.10 (IP-Port-Range-End TLV), Section 3.2.8 (IP-Port-Alloc TLV), Section 3.2.3 (IP-Port-Ext- IPv4-Addr TLV), and Section 3.2.11 (IP-Port-Local-Id TLV). Cheng, et al. Expires April 21, 2016 [Page 7] Internet-Draft RADIUS Extensions for IP Port October 2015 This attribute 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. 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. 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. The IP-Port-Range Attribute MAY appear in an Accounting-Request packet. The IP-Port-Range Attribute MUST NOT appear in any other RADIUS packets. The format of the IP-Port-Range Attribute format is shown in Figure 2. The fields are transmitted from left to right. 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: TBA1. Length: 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. Extended-Type: Cheng, et al. Expires April 21, 2016 [Page 8] Internet-Draft RADIUS Extensions for IP Port October 2015 TBA3. 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 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 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 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 Section 3.2.3. IP-Port-Local-Id TLV: 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 Section 3.2.11. Cheng, et al. Expires April 21, 2016 [Page 9] Internet-Draft RADIUS Extensions for IP Port October 2015 The IP-Port-Range attribute is associated with the following identifier: Type(TBA1).Extended-Type(TBA3).[IP-Port-Alloc TLV (TBA12), IP-Port-Type TLV(TBA5), {IP-Port-Range-Start TLV(TBA13), IP- Port-Range-End TLV(TBA14)}, {IP-Port-Ext-IPv4-Addr TLV (TBA7)}, {IP- Port-Local-Id TLV (TBA15)}]. 3.1.3. IP-Port-Forwarding-Map Attribute This attribute is RADIUS Extended-Type, and contains a set of embedded TLVs defined in Section 3.2.1(IP-Port-Type TLV), Section 3.2.6(IP-Port-Int-Port TLV), Section 3.2.7(IP-Port-Ext-Port TLV), Section 3.2.4(IP-Port-Int-IPv4-Addr TLV) or Section 3.2.5(IP-Port- Int-IPv6-Addr TLV), Section 3.2.11(IP-Port-Local-Id TLV) and Section 3.2.3 (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. 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. 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 attribute MUST NOT appear in any other RADIUS packet. The format of the IP-Port-Forwarding-Map Attribute is shown in Figure 3. The fields are transmitted from left to right. 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 Cheng, et al. Expires April 21, 2016 [Page 10] Internet-Draft RADIUS Extensions for IP Port October 2015 Type: TBA1. Length: 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. Extended-Type: TBA4. 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 the 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-Map 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 IPv4 network, either this TLV or IP-Port-Local-Id 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: Cheng, et al. Expires April 21, 2016 [Page 11] Internet-Draft RADIUS Extensions for IP Port October 2015 This TLV contains an IPv4 address that is associated with the internal IP port number contained in the IP-Port-Int-Port TLV. For IPv6 network, either this TLV or IP-Port-Local-Id TLV must be included as part of the IP-Port-Forwarding-Map Attribute. Refer to Section 3.2.5. IP-Port-Local-Id TLV: 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 Section 3.2.11. 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. The IP-Port-Forwarding-Map attribute is associated with the following identifier: Type(TBA1).Extended-Type(TBA4). [IP-Port-Int-Port TLV(TBA10), IP-Port-Ext-Port TLV(TBA11), IP-Port-Type TLV(TBA5), {IP- Port-Int-IPv4-Addr TLV(TBA8) | IP-Port-Int-IPv6-Addr TLV(TBA9)}, {IP- Port-Ext-IPv4-Addr TLV(TBA7)}]. 3.2. RADIUS TLVs for IP Ports 3.2.1. IP-Port-Type TLV This TLV (Figure 4) uses the format defined in [RFC6929]. Its Type field contains a value that uniquely refers to IPFIX Element transportType (TBAx1), and its Value field contains IPFIX Element transportType, which indicates the type of IP transport type as follows: 1: Refer to TCP port, UDP port, and ICMP identifier as a whole. 2: Refer to TCP port and UDP port as a whole. 3: Refer to TCP port only. Cheng, et al. Expires April 21, 2016 [Page 12] Internet-Draft RADIUS Extensions for IP Port October 2015 4: Refer to UDP port only. 5: Refer to ICMP identifier only. 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 | transportType +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ transportType | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4 Type: TBA5: This uniquely refers to IPFIX Element ID TBA0. Length: 6. transportType: Integer. This field contains the data (unsigned8) of transportType (TBX1) defined in IPFIX, right justified, and the unused bits in this field must be set to zero. 3.2.2. IP-Port-Limit TLV This TLV (Figure 5) uses the format defined in [RFC6929]. Its Type field contains a value that uniquely refers to IPFIX Element natTransportLimit (TBAx2), and its Value field contains IPFIX Element natTransportLimit, which indicates the maximum number of ports of a specified IP-Port-Type and associated with a given IPv4 address assigned to a subscriber. Cheng, et al. Expires April 21, 2016 [Page 13] Internet-Draft RADIUS Extensions for IP Port October 2015 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 | natTransportLimit +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ natTransportLimit | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5 Type: TBA6: This uniquely refers to IPFIX Element ID Limit TBD. Length: 6. natTransportLimit: Integer. This field contains the data (unsigned16) of natTransportLimit (TBX2) defined in IPFIX, right justified, and the unused bits in this field must be set to zero. 3.2.3. IP-Port-Ext-IPv4-Addr TLV This TLV (Figure 6) uses the format defined in[RFC6929]. Its Type field contains a value that uniquely refers to IPFIX Element postNATSourceIPv4Address(225), and its Value field contains IPFIX Element postNATSourceIPv4Address, which is the IPv4 source address after NAT operation (refer to [IPFIX]). IP-Port-Ext-IPv4-Addr TLV can be included as part of the IP-Port- Limit Attribute (refer to Section 3.1.1), IP-Port-Range Attribute (refer to Section 3.1.2), and IP-Port-Forwarding-Map Attribute (refer to Section 3.1.3). 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 | postNATSourceIPv4Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ postNATSourceIPv4Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 6 Cheng, et al. Expires April 21, 2016 [Page 14] Internet-Draft RADIUS Extensions for IP Port October 2015 Type: TBA7: The type field uniquely refers to the IPFIX Element ID 225. Length: 6 postNATSourceIPv4Address: Integer. This field contains the data (ipv4Address) of postNATSourceIPv4Address (225) defined in IPFIX. 3.2.4. IP-Port-Int-IPv4-Addr TLV This TLV (Figure 7) uses format defined in [RFC6929]. Its Type field contains a value that uniquely refers to IPFIX Element sourceIPv4Address (8), and its Value field contains IPFIX Element sourceIPv4Address, which is the IPv4 source address before NAT operation (refer to [IPFIX]). IP-Port-Int-IPv4-Addr TLV can be included as part of the IP-Port- Forwarding-Map Attribute (refer to Section 3.1.3). 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 | sourceIPv4Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceIPv4Address | +-+--+-+-+-+-+-+-++-+-+-+-+-+-+-+ Figure 7 Type: TBA8: The type field uniquely refers to the IPFIX Element ID 8. Length: 6. sourceIPv4Address: Integer. This field contains the data (ipv4Address) of sourceIPv4Address (8) defined in IPFIX. Cheng, et al. Expires April 21, 2016 [Page 15] Internet-Draft RADIUS Extensions for IP Port October 2015 3.2.5. IP-Port-Int-IPv6-Addr TLV This TLV (Figure 8) uses format defined in [RFC6929]. Its Type field contains a value that uniquely refers to IPFIX Element sourceIPv6Address(27), and its Value field contains IPFIX Element sourceIPv6Address, which is the IPv6 source address before NAT operation (refer to [IPFIX]). IP-Port-Int-IPv6-Addr TLV can be included as part of the IP-Port- Forwarding-Map Attribute (refer to Section 3.1.3). 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 | sourceIPv6Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceIPv6Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceIPv6Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceIPv6Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceIPv6Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 8 Type: TBA9: The type field uniquely refers to the IPFIX Element ID 27. Length: 18. sourceIPv6Address: IPv6 address (128 bits). This field contains the data (ipv6Address) of sourceIPv6Address (27) defined in IPFIX. 3.2.6. IP-Port-Int-Port TLV This TLV (Figure 9) uses format defined in [RFC6929]. Its Type field contains a value that uniquely refers to IPFIX Element sourceTransportPort (7), and its Value field contains IPFIX Element sourceTransportPort, which is the source transport number associated with an internal IPv4 or IPv6 address (refer to [IPFIX]). Cheng, et al. Expires April 21, 2016 [Page 16] Internet-Draft RADIUS Extensions for IP Port October 2015 IP-Port-Int-Port TLV is included as part of the IP-Port-Forwarding- Map Attribute (refer to Section 3.1.3). 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 | sourceTransportPort +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ sourceTransportPort | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 9 Type: TBA10: This uniquely refers to the IPFIX Element ID 7. Length: 4. sourceTransportPort: Integer. This field contains the data (unsigned16) of sourceTrasnportPort (7) defined in IPFIX, right justified, and unused bits must be set to zero. 3.2.7. IP-Port-Ext-Port TLV This TLV (Figure 10) uses format defined in [RFC6929]. Its Type field contains a value that uniquely refers to IPFIX Element postNAPTSourceTransportPort (227), and its Value field contains IPFIX Element postNAPTSourceTransportPort, which is the transport number associated with an external IPv4 address(refer to [IPFIX]). IP-Port-Ext-Port TLV is included as part of the IP-Port-Forwarding- Map Attribute (refer to Section 3.1.3). Cheng, et al. Expires April 21, 2016 [Page 17] Internet-Draft RADIUS Extensions for IP Port October 2015 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 | postNAPTSourceTransportPort +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ postNAPTSourceTransportPort | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 10 Type: TBA11: This uniquely refers to the IPFIX Element ID 227 . Length: 6. postNAPTSourceTransportPort: Integer. This field contains the data (unsigned16) of postNAPTSourceTrasnportPort (227) defined in IPFIX, right justified, and unused bits must be set to zero. 3.2.8. IP-Port-Alloc TLV This TLV (Figure 11) uses format defined in [RFC6929]. Its Type field contains a value that uniquely refers to IPFIX Element natEvent (230), and its Value field contains IPFIX Element "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 de-allocate a range of transports ports. For the purpose of this TLV, no other value is used. IP-Port-Alloc TLV is included as part of the IP-Port-Range Attribute (refer to Section 3.1.2). Cheng, et al. Expires April 21, 2016 [Page 18] Internet-Draft RADIUS Extensions for IP Port October 2015 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 | natEvent +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ natEvent | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 11 Type: TBA12: This uniquely refers to the IPFIX Element ID 230 . Length: 3. 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: 1: Allocation 2: Deallocation Reserved: 0. 3.2.9. IP-Port-Range-Start TLV This TLV (Figure 12) uses format defined in [RFC6929]. Its Type field contains a value that uniquely refers to IPFIX Element portRangeStart (361), and its Value field contains IPFIX Element portRangeStart, which is the smallest port number of a range of contiguous transport ports (refer to [IPFIX]). IP-Port-Range-Start TLV is included as part of the IP-Port-Range Attribute (refer to Section 3.1.2). Cheng, et al. Expires April 21, 2016 [Page 19] Internet-Draft RADIUS Extensions for IP Port October 2015 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 | portRangeStart +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ portRangeStart | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 12 Type: TBA13: This uniquely refers to the IPFIX Element ID 361. TLV8-Length: 4. portRangeStart: Integer. This field contains the data (unsigned16) of (361) defined in IPFIX, right justified, and unused bits must be set to zero. 3.2.10. IP-Port-Range-End TLV This TLV (Figure 13) uses format defined in [RFC6929]. Its Type field contains a value that uniquely refers to IPFIX Element portRangeEnd (362), and its Value field contains IPFIX Element portRangeEnd, which is the largest port number of a range of contiguous transport ports (refer to [IPFIX]). IP-Port-Range-End TLV is included as part of the IP-Port-Range Attribute (refer to Section 3.1.2). 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 | portRangeEnd +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ portRangeEnd | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 13 Cheng, et al. Expires April 21, 2016 [Page 20] Internet-Draft RADIUS Extensions for IP Port October 2015 Type: TBA14: This uniquely refers to IPFIC Element ID 362. Length: 4. The Length field for IP-Port-Range-End TLV. portRangeEnd: Integer. This field contains the data (unsigned16) of (362) defined in IPFIX, right justified, and unused bits must be set to zero. 3.2.11. IP-Port-Local-Id TLV This TLV (Figure 14) uses format defined in [RFC6929]. Its Type field contains a value that uniquely refers to IPFIX Element localID (TBAx3), and its Value field contains IPFIX Element localID, which is a local significant identifier as explained below. In some CGN deployment scenarios such as DS-Extra-Lite [RFC6619] and Lightweight 4over6 [I-D.ietf-softwire-lw4over6], 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. IP-Port-Local-Id TLV can be included as part of the IP-Port-Range Attribute (refer to Section 3.1.2) and IP-Port-Forwarding-Map Attribute (refer to Section 3.1.3). 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 | localID .... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 14 Type: TBA15: This uniquely refers to IPFIX Element ID TBD. Length: Variable number of bytes. Cheng, et al. Expires April 21, 2016 [Page 21] Internet-Draft RADIUS Extensions for IP Port October 2015 localID: string. This field contains the data (string) of (TBAX3) defined in IPFIX. 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. 4. Applications, Use Cases 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 Behavior using RADIUS 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. 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. 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. 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 following sub-sections, we describe how to manage CGN behavior using RADIUS protocol, with required RADIUS extensions proposed in Section 3. Cheng, et al. Expires April 21, 2016 [Page 22] Internet-Draft RADIUS Extensions for IP Port October 2015 4.1.1. Configure IP Port Limit for a User 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 [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 subscribers. As indicated in [RFC6269], 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 [RFC6888] as a requirement. 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 Section 3.1.1. 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. 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 Section 3.1.1), 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. Figure 15 illustrates how RADIUS protocol is used to configure the maximum number of TCP/UDP ports for a given subscriber on a NAT44 device. Cheng, et al. Expires April 21, 2016 [Page 23] Internet-Draft RADIUS Extensions for IP Port October 2015 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) | | | | Figure 15: RADIUS Message Flow for Configuring NAT44 Port Limit The IP port limit created on a CGN device for a specific user using RADIUS extension may be changed using 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 accepts and sends back a RADIUS CoA ACK message, the new IP port limit replaces the previous one. Figure 16 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. 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--------->| | | | Figure 16: RADIUS Message Flow for changing a user's NAT44 port limit Cheng, et al. Expires April 21, 2016 [Page 24] Internet-Draft RADIUS Extensions for IP Port October 2015 4.1.2. Report IP Port Allocation/De-allocation 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. 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 Section 3.1.2). 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. 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. 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. 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. Figure 17 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. Cheng, et al. Expires April 21, 2016 [Page 25] Internet-Draft RADIUS Extensions for IP Port October 2015 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) | | | | Figure 17: RADIUS Message Flow for reporting NAT44 allocation/de- allocation of a port set 4.1.3. Configure Forwarding Port 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 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. Port Control Protocol [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 some deployment, all users need is Cheng, et al. Expires April 21, 2016 [Page 26] Internet-Draft RADIUS Extensions for IP Port October 2015 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. Figure 18 illustrates how RADIUS protocol is used to configure a forwarding port mapping on a NAT44 device by using RADIUS protocol. 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) | Figure 18: RADIUS Message Flow for configuring a forwarding port mapping 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 [RFC5176] 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. Figure 19 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 Cheng, et al. Expires April 21, 2016 [Page 27] Internet-Draft RADIUS Extensions for IP Port October 2015 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) | Figure 19: RADIUS Message Flow for changing a user's forwarding port mapping 4.1.4. An Example 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). 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. 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. 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. When Joe works on more applications with more outbound IP sessions and the port pool (3500-3540) is close to exhaust, the NAT44 device Cheng, et al. Expires April 21, 2016 [Page 28] Internet-Draft RADIUS Extensions for IP Port October 2015 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. 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. 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. 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. 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. 4.2. Report Assigned Port Set for a Visiting UE Figure 20 illustrates an example of the flow exchange which occurs when a visiting 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. Cheng, et al. Expires April 21, 2016 [Page 29] Internet-Draft RADIUS Extensions for IP Port October 2015 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) | | | | Figure 20: RADIUS Message Flow for reporting CPE allocation/de- allocation of a port set to a visiting UE 5. Table of Attributes This document proposes three new RADIUS attributes and their formats are as follows: o IP-Port-Limit: TBA1.TBA2.[TBA6, TBA5, {TBA7}] o IP-Port-Range: TBA1.TBA3.[TBA12, TBA5, {TBA13, TBA14}, {TBA7}, {TBA15}]. o IP-Port-Forwarding-Map: TBA1.TBA4.[TBA10, TBA11, TBA5, {TBA8 | TBA9}, {TBA7}] Cheng, et al. Expires April 21, 2016 [Page 30] Internet-Draft RADIUS Extensions for IP Port October 2015 The following table provides a guide as what type of RADIUS packets that may contain these attributes, and in what quantity. Request Accept Reject Challenge Acct. # Attribute Request 0+ 0+ 0 0 0+ TBA IP-Port-Limit 0 0 0 0 0+ TBA IP-Port-Range 0+ 0+ 0 0 0+ TBA 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 than what has been identified in [RFC2865]. 7. IANA Considerations This document requires new code point assignments for both IPFIX Elements and RADIUS attributes as explained in the following sections. 7.1. IANA Considerations on New IPFIX Elements The following are code point assignments for new IPFIX Elements as requested by this document: o transportType (refer to Section 3.2.1): The identifier of this IPFIX Element is TBAx1. The data type of this IPFIX Element is unsigned8, and the Element's value indicates TCP/UDP ports and ICMP Identifiers (1), TCP/UDP ports (2), TCP ports (3), UDP ports (4) or ICMP identifiers (5). o natTransportLimit (refer to Section 3.2.2): The identifier of this IPFIX Element is TBAx2. The data type of this IPFIX Element is unsigned16, and the Element's value is the max number of IP transport ports to be assigned to an end user associated with one or more IPv4 addresses. o localID (refer to Section 3.2.11): The identifier of this IPFIX Element is TBAx3. The data type of this IPFIX Element is string, and the Element's value is an IPv4 or IPv6 address, a MAC address, a VLAN ID, etc. Cheng, et al. Expires April 21, 2016 [Page 31] Internet-Draft RADIUS Extensions for IP Port October 2015 7.2. IANA Considerations on New RADIUS Attributes The following are new code point assignment for RADIUS extensions as requested by this document: o TBA1: This value is allocated from Radius Extended-Type space. Refer to Section 3.1.1, Section 3.1.2, and Section 3.1.3. o TBA2: This is allocated from TBA1, so TBA1.TBA2 identifies a new RADIUS attribute IP-Port-Limit. Refer to Section 3.1.1. o TBA3: This is allocated from TBA1, so TBA1.TBA3 indentifies a new RADIUS attribute IP-Port-Range. Refer to Section 3.1.2. o TBA4: This is allocated from TBA1, so TBA1.TBA4 indentifies a new RADISU attribute IP-Port-Forwarding-Map. Refer to Section 3.1.3. o TBA5 (refer to Section 3.2.1): This is for the Type field of IP- Port-Type TLV. It should be allocated as TLV data type. The Value filed of this TLV contains the data of IPFIX Element transportType (TBAx1). o TBA6 (refer to Section 3.2.2): This is for the Type field of IP- Port-Limit TLV. It should be allocated as TLV data type. The Value field of this TLV contains the data of IPFIX Element natTransportLimit(TBAx2). o TBA7 (refer to Section 3.2.3): This is for the Type field of IP- Port-Ext-IPv4-Addr TLV. It should be allocated as TLV data type. The Value field of this TLV contains the data of IPFIX Element postNATSourceIPv4Address(225). o TBA8 (refer to Section 3.2.4): This is for the Type field of IP- Port-Int-IPv4-Addr TLV. It should be allocated as TLV data type. The Value field of this TLV contains the data of IPFIX Element sourceIPv4Address(8). o TBA9 (refer to Section 3.2.5): This is for the Type field of IP- Port-Int-IPv6-Addr TLV. It should be allocated as TLV data type. The Value field of this TLV contains the data of IPFIX Element sourceIPv6Address(27). o TBA10 (refer to Section 3.2.6): This is for the Type field of IP- Port-Int-Port TLV. It should be allocated as TLV data type. The Value field of this TLV containss the data of IPFIX Element sourceTransportPort(7). Cheng, et al. Expires April 21, 2016 [Page 32] Internet-Draft RADIUS Extensions for IP Port October 2015 o TBA11 (refer to Section 3.2.7): This is for the Type field of IP- Port-Ext-port TLV. It should be allocated as TLV data type. The Value field of this TLV contains the data of IPFIX Element postNAPTSourceTransportPort(227). o TBA12 (refer to Section 3.2.8): This is for the Type field of IP- Port-Alloc TLV. It should be allocated as TLV data type. The Value field of this TLV contains the data of IPFIX Element natEvent(230). o TBA13 (refer to Section 3.2.9): This is for the Type field of IP- Port-Range-Start TLV. It should be allocated as TLV data type. The Value field of this TLV contains the data of IPFIX Element portRangeStart(361). o TBA14 (refer to Section 3.2.10): This is for the Type field of IP- Port-Range-End TLV. It should be allocated as TLV data type. The Value field of this TLV contains the data of IPFIX Element portRangeEnd(362). o TBA15 (refer to Section 3.2.11): This is for the Type field of IP- Port-Local-Id TLV. It should be allocated as TLV data type. The Value field of this TLV contains the data of IPFIX Element localID(TBAx3). 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. 9. References 9.1. Normative References [IPFIX] IANA, "IP Flow Information Export (IPFIX) Entities", . [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, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Cheng, et al. Expires April 21, 2016 [Page 33] Internet-Draft RADIUS Extensions for IP Port October 2015 [RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, DOI 10.17487/RFC2629, June 1999, . [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, . [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, . [RFC6929] DeKok, A. and A. Lior, "Remote Authentication Dial In User Service (RADIUS) Protocol Extensions", RFC 6929, DOI 10.17487/RFC6929, April 2013, . [RFC7012] Claise, B., Ed. and B. Trammell, Ed., "Information Model for IP Flow Information Export (IPFIX)", RFC 7012, DOI 10.17487/RFC7012, September 2013, . [TR-146] Broadband Forum, "TR-146: Subscriber Sessions", . 9.2. 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. [I-D.ietf-softwire-lw4over6] Cui, Y., Qiong, Q., Boucadair, M., Tsou, T., Lee, Y., and I. Farrer, "Lightweight 4over6: An Extension to the DS- Lite Architecture", draft-ietf-softwire-lw4over6-13 (work in progress), November 2014. [RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network Address Translator (Traditional NAT)", RFC 3022, DOI 10.17487/RFC3022, January 2001, . Cheng, et al. Expires April 21, 2016 [Page 34] Internet-Draft RADIUS Extensions for IP Port October 2015 [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, . [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, . [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- Stack Lite Broadband Deployments Following IPv4 Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011, . [RFC6619] Arkko, J., Eggert, L., and M. Townsley, "Scalable Operation of Address Translators with Per-Interface Bindings", RFC 6619, DOI 10.17487/RFC6619, June 2012, . [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, . [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, . [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, . Authors' Addresses Dean Cheng Huawei 2330 Central Expressway Santa Clara, California 95050 USA Email: dean.cheng@huawei.com Cheng, et al. Expires April 21, 2016 [Page 35] Internet-Draft RADIUS Extensions for IP Port October 2015 Jouni Korhonen Broadcom Corporation 3151 Zanker Road San Jose 95134 USA Email: jouni.nospam@gmail.com Mohamed Boucadair France Telecom Rennes France Email: mohamed.boucadair@orange.com Senthil Sivakumar Cisco Systems 7100-8 Kit Creek Road Research Triangle Park, North Carolina USA Email: ssenthil@cisco.com Cheng, et al. Expires April 21, 2016 [Page 36]