Network Working Group M. Boucadair
Internet-Draft France Telecom
Intended status: Standards Track R. Penno
Expires: June 24, 2011 Juniper Networks
D. Wing
Cisco
F. Dupont
ISC
December 23, 2010

Universal Plug and Play (UPnP) Internet Gateway Device (IGD)-Port Control Protocol (PCP) Interworking Function
draft-bpw-pcp-upnp-igd-interworking-01

Abstract

This document specifies the behavior of the UPnP IGD (Internet Gateway Device)/PCP Interworking Function. An UPnP IGD-PCP Interworking Function (IGD-PCP IWF) is required to be embedded in CP routers to allow for transparent NAT control in environments where UPnP is used in the LAN side and PCP in the external side of the CP router.

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 June 24, 2011.

Copyright Notice

Copyright (c) 2010 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

PCP [I-D.ietf-pcp-base] discusses the implementation of NAT control features that rely upon Carrier Grade NAT devices such as DS-Lite AFTR [I-D.ietf-softwire-dual-stack-lite] or NAT64 [I-D.ietf-behave-v6v4-xlate-stateful]. Nevertheless, in environments where UPnP is used in the local network, an interworking function between UPnP IGD and PCP is required to be embedded in the CP router (an example is illustrated in Figure 1).

Two configurations are considered:

                         UPnP-PCP
UPnP Control           Interworking
   Point                 Function                  PCP Server
     |                      |                           |
     | (1) AddPortMapping   |                           |
     |--------------------->|                           |
     |                      |   (2) PCP PINxy Request   |
     |                      |-------------------------->|
     |                      |                           |

Figure 1: Flow Example

The UPnP IGD-PCP Interworking Function (IGD-PCP IWF) maintains a local mapping table which stores all active mappings instructed by internal UPnP Control Points. This design choice restricts the amount of PCP messages to be exchanged with the PCP Server.

Triggers for deactivating the UPnP IGD-PCP Interworking Function from the CP router and relying on a PCP-only mode are out of scope of this document.

In the remaining, PINxy refers to one of the PIN44, PIN46, PING64 and PIN66 PCP OpCodes defined in [I-D.ietf-pcp-base].

2. Acronyms

This document make use of the following abbreviations:

CP router Customer Premise router
DS-Lite Dual-Stack Lite
IGD Internet Gateway Device
IWF Interworking Function
NAT Network Address Translation
PCP Port Control Protocol
UPnP Universal Plug and Play

3. Architecture Model

As a reminder, Figure 2 illustrates the architecture model adopted by UPnP IGD [IGD2]. In Figure 2, the following UPnP terminology is used:

+-------------+
| IGD Control |
|   Point     |-----+
+-------------+     |   +-----+       +------+ 
                    +---|     |       |      |
                        | IGD |-------| Host |
                    +---|     |       |      |
+-------------+     |   +-----+       +------+
|   Client    |-----+
+-------------+

Figure 2: UPnP IGD Model

This model is not valid when PCP is used to control for instance a Carrier Grade NAT (a.k.a., Provider NAT) while internal hosts continue to use UPnP. In such scenarios, Figure 3 shows the updated model.

+-------------+
| IGD Control |
|   Point     |-----+
+-------------+     |   +-----+       +--------+               +------+
                    +---| IGD-|       |Provider|               |      |
                        | PCP |-------|  NAT   |--<Internet>---| Peer |
                    +---| IWF |       |        |               |      |
+-------------+     |   +-----+       +--------+               +------+
| Local Host  |-----+
+-------------+ 
                      LAN Side  External Side              
<======UPnP IGD===============><======PCP=====>

Figure 3: UPnP IGD-PCP Interworking Model

In the updated model depicted in Figure 3, one or two levels of NAT can be encountered in the data path. Indeed, in addition to the Carrier Grade NAT, the CP router may embed a NAT function (Figure 4).

+-------------+
| IGD Control |
|   Point     |-----+
+-------------+     |   +-----+       +----+               +------+
                    +---| IGD-|       |    |               |Remote|
                        | PCP |-------|NAT2|--<Internet>---| Host |
                    +---| IWF |       |    |               |      |
+-------------+     |   +-----+       +----+               +------+
| Local Host  |-----+     NAT1
+-------------+

Figure 4: Cascaded NAT scenario

To ensure a successful interworking between UPnP IGD and PCP, an interworking function is embedded in the CP router. In the model defined in Figure 3, all UPnP IGD server-oriented functions, a PCP Client [I-D.ietf-pcp-base] and a UPnP IGD-PCP Interworking Function are embedded in the CP router (i.e., IGD). In the rest of the document, IGD-PCP Interworking Function refers to PCP Client and UPnP IGD-PCP Interworking Function.

UPnP IGD-PCP Interworking Function is responsible for generating a well-formed PCP (resp., UPnP IGD) message from a received UPnP IGD (resp., PCP) message.

4. UPnP IGD-PCP Interworking Function: Overview

Three tables are provided to specify the mapping between UPnP IGD and PCP:

  1. Table 1 provides the mapping between WANIPConnection parameters and PCP parameters;
  2. Table 2 focuses on the correspondence between supported methods;
  3. Table 3 lists the IGD error messages and their corresponding PCP ones.

Note that some enhancements have been integrated in WANIPConnection as documented in [IGD2].

4.1. UPnP IGD-PCP: Variables

UPnP IGD-PCP: Variables
WANIPConnection PCP Comments
PortMappingEnabled Not applicable When set to 1, this parameter MUST NOT be reproduced as an argument in PCP messages. If set to 0, this is the default PCP mode (no explicit indication in PCP messages). PCP does not support deactivating the dynamic NAT mapping since the initial goal of PCP is to ease the traversal of Carrier Grade NAT. Supporting such per-subscriber function may overload the Carrier Grade NAT.
PortMappingLeaseDuration Requested Mapping Lifetime PCP recommends 7200s as default value. When PortMappingLeaseDuration is set to 0, a maximum lifetime value MAY be included in the corresponding PCP message. PCP allows for a maximum value of 65536 seconds while UPnP IGD allows 604800 seconds (i.e., one week) as a maximum bound. 3600s being the recommended lease value in UPnP IGD:2 [IGD2].
ExternalPort External Port Number PCP does not support explicit wildcard values. If ExternalPort is a wildcard value, a random value of External Port Number MUST be enclosed in the corresponding PCP message.
InternalPort Internal Port Number
PortMappingProtocol Transport Protocol IGD only supports TCP and UDP.
InternalClient Internal IP Address InternalClient can be an IP address or a FQDN. Only an IP address scheme is supported in PCP. If a FQDN is used by the IGD Control Point, it must be resolved to an IP address by the Interworking Function when relying the message to the PCP Server.
ExternaIPAddress External IP Address
PortMappingDescription Not applicable Not supported in base PCP. When present in UPnP IGD messages, this parameter SHOULD NOT be propagated in the corresponding PCP messages. If the local PCP Client support a PCP Option to convey the description, this option MAY be used.
RemoteHost REMOTE_PEER PCP RECOMMENDS to configure the CP router's firewall instead of overloading the Carrier Grade NAT. The REMOTE_PEER PCP Option can be used.
PossibleConnectionTypes Not applicable Out of scope of PCP
ConnectionStatus Not applicable Out of scope of PCP
PortMappingNumberOfEntries Not applicable Managed locally by the UPnP IGD-PCP Interworking Function
SystemUpdateID Not applicable Managed locally by the UPnP IGD-PCP Interworking Function

4.2. IGD-PCP: Methods

Both IGD:1 and IGD:2 methods are listed in Table 2.

IGD-PCP: Methods
WANIPConnection PCP Comments
GetGenericPortMappingEntry Not applicable This request is not relayed to the PCP Server. IGD-PCP Interworking Function maintains an updated list of active mappings instantiated in the PCP Server by internal hosts. See Section 5.8 for more information.
GetSpecificPortMappingEntry Not applicable Under normal conditions, the IGD-PCP Interworking Function maintains an updated list of active mapping as instantiated in the PCP Server. The IGD-PCP Interworking Function locally handles this request and provides back the port mapping entry based on the ExternalPort, the PortMappingProtocol, and the RemoteHost. See Section 5.8 for more information
AddPortMapping PINxy We recommend the use of AddAnyPortMapping() instead of AddPortMapping(). Refer to Section 5.7.2
DeletePortMapping PINxy with a requested lifetime set to 0 Refer to Section 5.9
GetExternalIPAddress PCP does not support yet a method for retrieving the external IP address. Issuing PINxy may be used as a means to retrieve the external IP address
DeletePortMappingRange() PINxy with a lifetime positioned to 0 Individual requests are issued by the IGD-PCP Interworking Function. Refer to Section 5.9 for more details
GetListOfPortMappings() Not applicable The IGD-PCP Interworking Function maintains an updated list of active mapping as instantiated in the PCP Server. The IGD-PCP Interworking Function handles locally this request. See Section 5.8 for more information
AddAnyPortMapping() PINxy No issue is encountered to proxy this request to the PCP Server. Refer to Section 5.7.1 for more details

4.3. UPnP IGD-PCP: Errors

Table 3 lists UPnP IGD errors codes and the corresponding PCP ones. Error codes specific to IGD:2 are tagged accordingly.

UPnP IGD-PCP: Errors
IGD Error Code PCP Error Code
401 (InvalidAction) 129 (UNSUPP_OPCODE)
402 (InvalidArgs) TBD (MALFORMED_REQUEST)
501(ActionFailed) 154 (UNABLE_TO_DELETE_ALL) (??)
606 (ActionNotAuthorized) (only for IGD:2) 151 (NOT_AUTHORIZED)
713 (SpecifiedArrayIndexInvalid) Not applicable because Get* requests are not relayed to the PCP Server
714 (NoSuchEntryInArray) PCP returns always a positive response even if the mapping to be deleted does not exist. This error code is not applicable for Get* requests which are not relayed to the PCP Server
715 (WildCardNotPermitedInSrcIP) TBD (MALFORMED_REQUEST)
716 (WildCardNotPermitedInSrcExtPort) Not applicable
718 (ConflictInMappingEntry) Not applicable
724 (SamePortValuesRequired) Not applicable
725 (OnlyPermanentLeaseSupported) Not applicable
726 (RemoteHostOnlySupportsWildcard) 130 (UNSUPP_OPTION)
727 (ExternalPortOnlySupportsWildcard) Not applicable
728 (NoPortMapsAvailable) (only for IGD:2) 4 (NO_RESOURCES) or 152 (USER_EX_QUOTA)
729 (ConflictWithOtherMechanisms) (only for IGD:2) TBD (MECHANISM_CONFLICT)
730 (PortMappingNotFound) (only for IGD:2) Not applicable
732 (WildCardNotPermittedInPort) (only for IGD:2) TBD (MALFORMED_REQUEST)
733 (InconsistentParameter) (only for IGD:2) Not applicable

5. Specification of the IGD-PCP Interworking Function

This section covers the scenarios with or without NAT in the CP router.

5.1. PCP Server Discovery

The IGD-PCP Interworking Function implements one of the discovery methods identified in [I-D.ietf-pcp-base] (e.g., DHCP [I-D.bpw-pcp-dhcp]). The IGD-PCP Interworking Function behaves as a PCP Client when communicating with the provisioned PCP Server.

In order to not impact the delivery of local services requiring the control of the local IGD during any failure event to reach the PCP Server (e.g., no IP address/prefix is assigned to the CP router), IGD-PCP Interworking Function MUST NOT be invoked. Indeed, UPnP machinery is used to control that device and therefore lead to successful operations of internal services.

Once the PCP Sever is reachable, the IGD-PCP Interworking Function MUST synchronize its states as specified in Section 5.10.

5.2. Control of the Firewall

In order to configure security policies to be applied to inbound and outbound traffic, UPnP IGD can be used to control a local firewall engine.

No IGD-PCP Interworking Function is therefore required for that purpose.

5.3. NAT Control in LAN Side

Internal UPnP Control Points are not aware of the presence of the IGD-PCP Interworking Function in the CP router (IGD). Especially, UPnP Control Points MUST NOT be aware of the deactivation of the NAT in the CP router.

No modification is required in the UPnP Control Point.

5.4. Port Mapping Tables

IGD-PCP Interworking Function MUST store locally all the mappings instantiated by internal UPnP Control Points in the PCP Server. Port Forwarding mappings SHOULD be stored in a permanent storage. If not, upon reset or reboot, the IGD-PCP Interworking Function MUST synchronise its states as specified in Section 5.10.

Upon receipt of a PCP PINxy Response from the PCP Server, the IGD-PCP Interworking Function MUST retrieve the enclosed mapping(s) and MUST store it in the local mapping table. The local mapping table is an image of the mapping table as maintained by the PCP Server for a given subscriber.

5.5. Interworking Function Without NAT in the CP Router

When no NAT is embedded in the CP router, the content of received WANIPConnection and PCP messages is not altered by the IGD-PCP Interworking Function (i.e., the content of WANIPConnection messages are copied to the PCP messages (and vice versa) according to Table 1).

5.6. NAT Embedded in the CP Router

Unlike the scenario with one level of NAT (Section 5.5), the IGD-PCP Interworking Function MUST update their content of received mapping messages with the IP address and/or port number belonging to the external interface of the CP router (i.e., after the NAT1 operation in Figure 4) and not as initially positioned by the UPnP Control Point.

All WANIPConnection messages issued by the UPnP Control Point (resp., PCP Server) are intercepted by the IGD-PCP Interworking Function. Then, the corresponding messages (see Table 1, Table 2 and Table 3) are generated by the IGD-PCP Interworking Function and sent to the provisioned PCP Server (resp., corresponding UPnP Control Point). The content of PCP messages received by the PCP Server reflects the mapping information as enforced in the first NAT. In particular, the internal IP address and/or port number of the requests are replaced with the IP address and port number as assigned by the NAT of the CP router. For the reverse path, PCP response messages are intercepted by the IGD-PCP Interworking Function. The content of the corresponding WANIPConnection messages are updated:

  • The internal IP address and/or port number as initially positioned by the UPnP Control Point and stored in the CP router NAT are used to update the corresponding fields in received PCP responses.
  • The external IP and port number are not altered by the IGD-PCP Interworking Function.
  • The NAT mapping entry in the first NAT is updated with the result of PCP request.

The lifetime of the mappings instantiated in all involved NATs SHOULD be the one assigned by the terminating PCP Server. In any case, the lifetime MUST be lower or equal to the one assigned by the terminating PCP Server.

5.7. Creating a Mapping

Two methods can be used to create a mapping: AddPortMapping() or AddAnyPortMapping().

AddAnyPortMapping() is the RECOMMENDED method.

5.7.1. AddAnyPortMapping()

When an UPnP Control Point issues a AddAnyPortMapping(), this request is received by the UPnP Server. The request is then relayed to the IGD-PCP Interworking Function which generates a PCP PINxy Request (see Table 1 for mapping between WANIPConnection and PCP parameters). Upon receipt of PCP PINxy Response from the PCP Server, an XML mapping is returned to the requesting UPnP Control Point (the content of the messages follows the recommendations listed in Section 5.6 or Section 5.5 according to the deployed scenario). A flow example is depicted in Figure 5.

If a PCP Error is received from the PCP Server, a corresponding WANIPConnection error code Table 3 is generated by the IGD-PCP Interworking Function and sent to the requesting UPnP Control Point.

                         UPnP-PCP
UPnP Control           Interworking
   Point                 Function                    PCP Server
     |                      |                             |
     |(1) AddAnyPortMapping |                             |
     |--------------------->|                             |
     |                      |   (2) PCP PINxy Request     |
     |                      |(requested external port=0)  |
     |                      |---------------------------->|
     |                      |                             |
     |                      |   (3) PCP PINxy Response    |
     |                      |(assigned external port=6598)|
     |                      |<----------------------------|
     |(4) AddAnyPortMapping |                             |
     |   ReservedPort=6598  |                             |
     |<---------------------|                             |

Figure 5: Flow example when AddAnyPortMapping() is used

5.7.2. AddPortMapping()

A dedicated option called HONOR_EXTERNAL_PORT is defined in [I-D.ietf-pcp-base] to toggle the behavior in a PCP Request message. This options is inserted by the IGD-PCP IWF when issuing its requests to the PCP Server only if a specific external port is requested by the UPnP Control Point. When a wildcard is used (i.e., 0), HONOR_EXTERNAL_PORT Option is not required to be inserted in the PCP request to the PCP Server (see Figure 6). In the remaining, we assume that a specific external port is requested by the UPnP Control Point.

                         UPnP-PCP
UPnP Control           Interworking
   Point                 Function                   PCP Server
     |                      |                             |
     | (1) AddPortMapping   |                             |
     |   ExternalPort=0     |                             |
     |--------------------->|                             |
     |                      |   (2) PCP PINxy Request     |
     |                      |(requested external port=0)  |
     |                      |---------------------------->|
     |                      |                             |
     |                      |   (3) PCP PINxy Response    |
     |                      |(assigned external port=1365)|
     |                      |<----------------------------|
     |  (4) AddPortMapping  |                             |
     |   ExternalPort=1356  |                             |
     |<---------------------|                             |

Figure 6: Example of AddPortMapping() with wildcard external port

Upon receipt of AddPortMapping() from an UPnP Control Point, the IGD-PCP Interworking Function first checks if the requested external port number is not used by another Internal UPnP Control Point. In case a mapping bound to the requested external port number is found in the local mapping table, the IGD-PCP IWF MUST send back a ConflictInMappingEntry error to the requesting UPnP Control Point (see Figure 7).

                         UPnP-PCP
UPnP Control           Interworking
   Point                 Function                  PCP Server
     |                      |                           |
     | (1) AddPortMapping   |                           |
     |   ExternalPort=2356  |                           |
     |--------------------->|                           |
     |                      |                           |
     |     (2) Error:       |                           |
     |ConflictInMappingEntry|                           |
     |<---------------------|                           |
     |                      |                           |
     | (3) AddPortMapping   |                           |
     |   ExternalPort=4586  |                           |
     |--------------------->|                           |
     |                      |                           |
     |     (4) Error:       |                           |
     |ConflictInMappingEntry|                           |
     |<---------------------|                           |
     |                      |                           |

Figure 7: IWF Local Behaviour

This exchange (Figure 7) is re-iterated until an external port number that is not in use is requested by the UPnP Control Point. Then, the IGD-PCP IWF generates a PCP PINxy Request with all requested mapping information as indicated by the UPnP Control Point if no NAT is embedded in the CP router or updated as specified in Section 5.6. In addition, the IGD-PCP IWF inserts a HONOR_EXTERNAL_PORT Option to the generated PCP request.

If the requested external port is in use, a PCP Error message MUST be sent by the PCP Server to the IGD-PCP IWF indicating CANNOT_HONOR_EXTERNAL_PORT as the error cause. The IGD-PCP IWF relays a negative message to the UPnP Control Point indicating ConflictInMappingEntry as error code. The UPnP Control Point re-issues a new request with a new requested external port number. This process is repeated until a positive answer is received or maximum retry is reached.

If the PCP Server is able to honor the requested external port, a positive response is sent to the requesting IGD-PCP IWF. Upon receipt of the response from the PCP Server, the returned mapping MUST be stored by the IGD-PCP Interworking Function in its local mapping table and a positive answer MUST be sent to the requesting UPnP Control Point. This answer terminates this exchange.

Figure 8 shows an example of the flow exchange that occurs when the PCP Server satisfies the request from the IGD-PCP IWF. Figure 9 shows the messages exchange when the requested external port is in use.

                         UPnP-PCP
UPnP Control           Interworking
   Point                 Function                  PCP Server
     |                      |                             |
     | (1) AddPortMapping   |                             |
     |   ExternalPort=8080  |                             |
     |--------------------->|                             |
     |                      |   (2) PCP PINxy Request     |
     |                      |requested external port=8080 |
     |                      |     HONOR_EXTERNAL_PORT     |
     |                      |---------------------------->|
     |                      |                             |
     |                      |   (3) PCP PINxy Response    |
     |                      | assigned external port=8080 |
     |                      |<----------------------------|
     | (4) AddPortMapping   |                             |
     |   ExternalPort=8080  |                             |
     |<---------------------|                             |

Figure 8: Flow Example (Positive Answer)

                         UPnP-PCP
UPnP Control           Interworking
   Point                 Function                    PCP Server
     |                      |                             |
     | (1) AddPortMapping   |                             |
     |   ExternalPort=8080  |                             |
     |--------------------->|                             |
     |                      |   (2) PCP PINxy Request     |
     |                      |requested external port=8080 |
     |                      |     HONOR_EXTERNAL_PORT     |
     |                      |---------------------------->|
     |                      |   (3) PCP PINxy Response    |
     |                      | CANNOT_HONOR_EXTERNAL_PORT  | 
     |                      |<----------------------------|
     |     (4) Error:       |                             |
     |ConflictInMappingEntry|                             |
     |<---------------------|                             |
     | (5) AddPortMapping   |                             |
     |   ExternalPort=5485  |                             |
     |--------------------->|                             |
     |                      |   (6) PCP PINxy Request     |
     |                      |requested external port=5485 |
     |                      |     HONOR_EXTERNAL_PORT     |
     |                      |---------------------------->|
     |                      |   (7) PCP PINxy Response    |
     |                      | CANNOT_HONOR_EXTERNAL_PORT  |
     |                      |<----------------------------|
     |     (8) Error:       |                             |
     |ConflictInMappingEntry|                             |
     |<---------------------|                             |
                            ....
     | (a) AddPortMapping   |                             |
     |   ExternalPort=6591  |                             |
     |--------------------->|                             |
     |                      |   (b) PCP PINxy Request     |
     |                      |requested external port=6591 |
     |                      |     HONOR_EXTERNAL_PORT     |
     |                      |---------------------------->|
     |                      |   (c) PCP PINxy Response    |
     |                      | CANNOT_HONOR_EXTERNAL_PORT  |
     |                      |<----------------------------|
     |     (d) Error:       |                             |
     |ConflictInMappingEntry|                             |
     |<---------------------|                             |

Figure 9: Flow Example (Negative Answer)

5.8. Listing One or a Set of Mappings

In order to list active mappings, an UPnP Control Point may issue GetGenericPortMappingEntry(), GetSpecificPortMappingEntry() or GetListOfPortMappings().

These methods MUST NOT be proxied to the PCP Server since a local mapping is maintained by the IGD-PCP Interworking Function.

5.9. Delete One or a Set of Mappings: DeletePortMapping() or DeletePortMappingRange()

An UPnP Control Point proceeds to the deletion of one or a list of mappings by issuing DeletePortMapping() or DeletePortMappingRange(). When one of these messages is received by the IGD-PCP Interworking Function, it first checks if the requested mapping to be removed is present in the local mapping table. If no mapping matching the request is found in the local table, an error is sent back to the UPnP Control Point (see Figure 10).

                         UPnP-PCP
UPnP Control           Interworking
   Point                 Function                  PCP Server
     |                      |                           |
     |(1) DeletePortMapping |                           |
     |--------------------->|                           |
     |                      |                           |
     |     (2) Error:       |                           |
     |  NoSuchEntryInArray  |                           |
     |<---------------------|                           |
     |                      |                           |

Figure 10: Local Delete (IGD-PCP IWF)

if a mapping matches in the local table, PCP PINxy delete request(s) is generated taking into account the input arguments:

  • as included in DeletePortMapping() if no NAT is enabled in the CP router; In case DeletePortMappingRange() is used, the IGD-PCP IWF generates individual requests to cover all the range;
    • [[Note: Add a figure to illustrate the behaviour to handle DeletePortMappingRange()]]
  • or the corresponding local IP address and port number as assigned by the local NAT if a NAT is enabled in the CP router.

Once received by the PCP Server, it proceeds to removing the corresponding entry(ies). A PCP PINxy delete response is sent back if the removal of the corresponding entry(ies) was successful; if not, a PCP Error is sent back to the IGD-PCP Interworking Function including the corresponding error cause (e.g., Not Authorised).

When a positive answer is received from the PCP Server, the IGD-PCP Interworking Function updates its local mapping table (i.e., remove the corresponding entry(ies)) and notifies the UPnP Control Point about the result of the removal operation.

5.10. Mapping Synchronisation

[[Note: This section needs further discussion among authors]]

Under normal conditions, since a valid copy of the mapping table is stored locally in the CP router, the IGD-PCP Interworking Function SHOULD NOT issue any subsequent PCP request to handle a request received from an UPnP Control Point to list active mappings. Nevertheless, in case of loss of synchronisation (e.g., reboot, system crashes, power outage, etc.), the IGD-PCP Interworking Function SHOULD generate a get method to retrieve all active mappings in the PCP Server and update its local mapping table without waiting for an explicit request from a UPnP Control Point. Doing so, the IGD-PCP Interworking Function maintains an updated mapping table.

In case of massive reboot of CP routers (e.g., avalanche restart phenomenon), PCP request bursts SHOULD be avoided. For this aim, we recommend the use of a given timer denoted as PCP_SERVICE_WAIT. This timer can be pre-configured in the CP router or to be provisioned using a dedicated means such as DHCP. Upon reboot of the CP router, PCP messages SHOULD NOT be sent immediately. A random value is selected between 0 and PCP_SERVICE_WAIT. This value is referred to as RAND(PCP_SERVICE_WAIT). Upon the expiration of RAND(PCP_SERVICE_WAIT), the CP router SHOULD proceed to its synchronisation operations (i.e., retrieve all active mappings which have been instructed by internal UPnP Control Point(s)).

[[Note: per-subscriber quota may be exhausted due to unlimited lifetime and stale mappings in IGD due to reboots, etc.]]

6. IANA Considerations

This document makes no request of IANA.

Note to RFC Editor: this section may be removed on publication as an RFC.

7. Security Considerations

This document defines a procedure to instruct PCP mappings for third party devices belonging to the same subscriber. Identification means to avoid a malicious user to instruct mappings on behalf of a third party must be enabled. Such means are already discussed in Section 7.4.4 of [I-D.ietf-pcp-base].

Security considerations elaborated in [I-D.ietf-pcp-base] and [Sec_DCP] should be taken into account.

8. Acknowledgments

Authors would like to thank F. Fontaine and C. Jacquenet for their review and comments.

9. References

9.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[I-D.ietf-pcp-base] Wing, D, Cheshire, S, Boucadair, M, Penno, R and P Selkirk, "Port Control Protocol (PCP)", Internet-Draft draft-ietf-pcp-base-17, October 2011.

9.2. Informative References

[I-D.ietf-softwire-dual-stack-lite] Durand, A, Droms, R, Woodyatt, J and Y Lee, "Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion", Internet-Draft draft-ietf-softwire-dual-stack-lite-11, May 2011.
[I-D.ietf-behave-v6v4-xlate-stateful] Bagnulo, M, Matthews, P and I Beijnum, "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", Internet-Draft draft-ietf-behave-v6v4-xlate-stateful-12, July 2010.
[I-D.bpw-pcp-dhcp] Boucadair, M, Penno, R and D Wing, "DHCP and DHCPv6 Options for the Port Control Protocol (PCP)", Internet-Draft draft-bpw-pcp-dhcp-04, April 2011.
[Sec_DCP] UPnP Forum, , "Device Protection:1", November 2009.
[IGD2] UPnP Forum, , "WANIPConnection:2 Service (http://upnp.org/specs/gw/UPnP-gw-WANIPConnection-v2-Service.pdf)", September 2010.

Authors' Addresses

Mohamed Boucadair France Telecom Rennes, 35000 France EMail: mohamed.boucadair@orange-ftgroup.com
Reinaldo Penno Juniper Networks 1194 N Mathilda Avenue Sunnyvale, California 94089 USA EMail: rpenno@juniper.net
Dan Wing Cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134 USA EMail: dwing@cisco.com
Francis Dupont ISC EMail: Francis.Dupont@fdupont.fr