| Network Working Group | M. Boucadair |
| Internet-Draft | France Telecom |
| Intended status: Standards Track | R. Penno |
| Expires: November 20, 2011 | Juniper Networks |
| D. Wing | |
| Cisco | |
| May 19, 2011 |
Some Extensions to Port Control Protocol (PCP)
draft-boucadair-pcp-extensions-00
This document extends Port Control Protocol (PCP) with some useful features.
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].
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 November 20, 2011.
Copyright (c) 2011 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.
This document extends the base PCP protocol [I-D.ietf-pcp-base] with various PCP Options.
Some of these options may be defined as new PCP OpCodes.
The main goal of this document is to kick-off discussions on the need to define some useful PCP options which are not part of base PCP.
This option (Code TBA, Figure 1) MAY be included in a PCP MAPx request to include a description associated with a requested mapping. This option is optional to be supported by PCP Servers and PCP Clients. The maximum length SHOULD be a configurable option in the PCP Server. If a PCP Client includes a Description PCP option with a length exceeding the maximum length supported by the PCP Server, only the portion of the Description field fitting that maximum length is stored by the PCP Server.
This option can be used by a user to indicate a description associated with a given mapping such as "My mapping for my FTP server" or "My remote access to my CP router", etc. In addition, in the some deployment scenarios, this field can be used for troubleshooting purposes and can be used to convey values as the ones listed hereafter:
Issues related to the usage of this field for troubleshooting or for any further usage are out of scope of this document.
This Option:
Name: Description Option (DESCRIPTION)
Number: TBA (IANA)
Purpose: Used to associate a text description with a mapping
is valid for OpCodes: MAP4, MAP6
Length: Variable (multiple of 4)
May appear in: both request and response
Maximum occurrences: 1
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DESCRIPTION | Reserved | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Description |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In some scenarios, the DSCP marking in the internal interface (i.e., customer-facing interface) and the external one (i.e., Internet-facing interface) of the PCP-controlled device may be distinct. A Service Provider MAY allow its customers to configure their DSCP marking policies in an upstream device. Distinct DSCP marking policies can be implemented in the internal and external sides of the PCP-controlled device. A PCP Client MAY issue a PCP MAPx request indicating its internal DS code point and the external DSCP value. Instructed forwarding policies are applied only for packets marked with a given DSCP value.
A Service Provider may not support DSCP re-marking feature and adopt a transparent scheme to QoS policy enforcement, that is, not controllable by subscribers. Generic QoS enforcement policies can be enforced for all customers: such as leave DSCP field values unchanged.
This option (Code TBA, Figure 2) allows to:
This Option:
Name: PCP DSCP Marking Policy Option (DSCP_POLICY)
Number: TBA (IANA)
Purpose: Associated a DSCP re-marking policy with a mapping
is valid for OpCodes: MAP4, MAP6
Length: 0x04
May appear in: both request and response
Maximum occurrences: none
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DSCP_POLICY | Reserved | 0x04 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|DIR| Int DSCP | Ext DSCP | 00...00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
DIR : Indicates the direction:
0 for Inbound
1 for Outbound
2 for Both
Int DSCP: Indicates the DSCP value in the customer-faced interface.
0x3F is used to indicate ANY value.
Ext DSCP: Indicates the DSCP value in the Internet-faced interface.
0x3F is used to indicate ANY value.
The CAPABILITY option (Code: TBA, Figure 3) is used by a PCP Server to indicate to a requesting PCP Client the capabilities it supports with regards to port forwarding operations. Several Capability options MAY be conveyed in the same PCP response message if several functions are co-located in the same PCP-controlled device (e.g., NAT44 and NAT64, NAT44 and ports set assignment capability, etc.).
This option, when received from a PCP Server, is used by a PCP Client to constraint the content of its requests and therefore avoid errors.
This Option:
Name: PCP Capabilities Option (CAPABILITY)
Number: TBA (IANA)
Purpose: Retrieve the capabilities of a PCP-controlled device
is valid for OpCodes: can be returned in a error message
Length: 0x04
May appear in: both request and response
Maximum occurrences: None
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CAPABILITY | Reserved | 0x04 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|F T P A S C I O| 00...00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Below is provided a description of the F, T, P, A, S, C, I and O bits:
| Name | Description |
|---|---|
| F | This bit indicates the address family of the source address issued by internal hosts |
| T | This bit indicates the address family of the source address of the packets forwarded in the external side of the PCP-controlled device |
| P | This bit indicates whether the source port number is translated or not. |
| A | This bit indicates whether the source IP address is translated or not. |
| S | This bit indicates whether the controlled device supports the ability to assign a set or ports |
| C | This bit indicates whether the PCP-controlled devices inspects the received packets and if it can block them |
| I | This bit indicates whether incoming packets are rejected unless an explicit rule is enforced in the PCP-controlled device |
| O | This bit indicates whether outbound packets are inspected or not before being granted to leave the internal realm. |
The value of the F, T, P, A, S, C, I and O bits are as follows:
| Position | Name | Meaning |
|---|---|---|
| 1 | From (F) | 0=from IPv4, 1=from IPv6 |
| 2 | To (T) | 0=to IPv4, 1=to IPv6 |
| 3 | Port-Xlate (P) | 1=translated, 0=not translated |
| 4 | Addr-Xlate (A) | 1=translated, 0=not translated |
| 5 | Port-Set (S) | 1=enabled, 0=not supported |
| 6 | Packet-Control (C) | 1=enabled, 0=not supported |
| 7 | Direction-Out (I) | 1=enabled, 0=disabled |
| 8 | Direction-In (O) | 1=enabled, 0=disabled |
A stateless NAT64 [RFC6145] would have the following values:
From=0 (IPv4) To=1 (IPv6) Port-Xlate=0 (No) Addr-Xlate=1 (Yes) Port-Set=0 (No) Packet-control=0 (No) Direction-out (0) (No) Direction-In=0 (No)
From=0 (IPv4) To=1 (IPv6) Port-Xlate=1 (Yes) Addr-Xlate=1 (Yes) Port-Set=0 (No) Packet-control=0 (No) Direction-out (0) (No) Direction-In=0 (No)
A NAT44 would be characterized as follows:
From=0 (IPv4) To=0 (IPv4) Port-Xlate=1 (Yes) Addr-Xlate=1 (Yes) Port-Set=0 (No) Packet-control=0 (No) Direction-out (0) (No) Direction-In=0 (No)
This option (Code TBA, Figure 7) is used by a PCP Server to indicate in a PCP Response the perceived IPv6/IPv4 address and port of PCP messages received from a PCP Client. A PCP Client uses this information to detect whether a NAT is present in the path to reach its PCP Server.
A PCP Client MAY include this option to learn the IP address and port as perceived by the PCP Server. When this option is received by the PCP Server, it uses the source IP address and port of the received PCP request to set the Perceived Port and Perceived IP Address.
This Option:
Name: PCP Perceived IP address/port Option (PERCEIVED_ADDR )
Number: TBA (IANA)
Purpose: Detect the presence of a NAT in the path
is valid for OpCodes: MAP4, MAP6
Length: 0x08
May appear in: both request and response
Maximum occurrences: 1
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|PERCEIVED_ADDR | Reserved | 0x08 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Perceived Port |Address Family | 00...00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Perceived IPv4/IPv6 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Perceived Port: The source port number of a PCP request as seen
by the PCP Server.
Address Family: The Address Family of the perceived IP address.
Perceived IPv4/IPv6 Address: If the Address Family is IPv4,
an IPv4 address followed by 96 zero bits. If the Address Family
is IPv6, an IPv6 address. This field includes the source IP
address of a PCP request as seen by the PCP Server.
An example of the use of this option is illustrated in the following figure where there is a NAT in the path between the PCP Client and the PCP Server.
webcam-------+
|
+----------+ | +----+ +----------+
|PCP Client|====+====|NAT1|=========|PCP Server|
+----------+ +----+ +----------+
NAT2
The Scope Option (Code TBA, Figure 9) is used by a PCP Client to indicate to the PCP Server the scope of the flows that will use a given mapping. This object is meant to be used in the context of cascaded PCP Servers/NAT levels. Two values are defined:
| Value | Meaning |
|---|---|
| 0x00 | Internet |
| 0x01 | Internal |
When 0x00 value is used, the PCP Proxy MUST propagate the mapping request to its upstream PCP Server. When 0x01 value is used, the mapping is to be instantiated only in the first PCP-controlled device; no mapping is instantiated in the upstream PCP-controlled device.
When no Scope Option is included in a PCP message, this is equivalent to including a Scope Option with a scope value of "Internet".
This Option:
Name: PCP Scope Policy Option (SCOPE)
Number: TBA (IANA)
Purpose: Restrict the scope of PCP requests
is valid for OpCodes: MAP4, MAP6
Length: 0x04
May appear in: both request and response
Maximum occurrences: 1
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SCOPE | Reserved | 0x04 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope | 00...00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Report PCP Option (Code TBA, Figure 10) is used by a PCP Client to report a set of useful information to the PCP Server. Several Report Options with distinct Report Sub-Code values MAY be conveyed in the same PCP message. Only report data associated with the PCP Server to which this option is sent MUST be included in a Report Option.
This option can be used for troubleshooting or diagnose purposes.
This Option:
Name: PCP Report Option (REPORT)
Number: TBA (IANA)
Purpose: Send a set of report data
is valid for OpCodes: MAP4, MAP6
Length: Variable
May appear in: both request and response
Maximum occurrences: Multiple
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SCOPE | Reserved | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Report Sub-Code | 00...00 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Report Data |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following Report Sub-Code values are defined:
| Position | Meaning |
|---|---|
| 0x00 | Time since last reboot/boot |
| 0x01 | Count of transmitted PCP messages to the PCP Server since last boot |
| 0x02 | Count of retransmitted PCP messages to the PCP Server since last boot |
| 0x03 | Count of received PCP Error messages from the PCP Server |
PCP CLIENT_ID (Code TBA, Figure 11) is a token randomly [RFC4086] generated by the PCP Client. Only one CLIENT_ID Option MUST be present in a PCP message. The PCP Client and PCP Server MUST store the value included in this Option in a PCP MAPx request.
This Option:
Name: PCP Client Identifier Option (CLIENT_ID)
Number: TBA (IANA)
Purpose: Associate an identifier with the mappings
is valid for OpCodes: MAP4, MAP6
Length: Variable
May appear in: both request and response
Maximum occurrences: 1
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CLIENT_ID | Reserved | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Client Identifier |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The length of the CLIENT_ID is encoded in the Length field in bytes. The length of the CLIENT_ID MUST be at least 4 bytes and MUST NOT exceed 16 bytes.
The RECOMMENDED value is 16 bytes so as to have a robust random CLIENT_ID. If a CLIENT_ID longer than 16 bytes or shorter than 4 bytes is received, the PCP Server MUST issue a PCP Error message with an error cause equal to "Invalid Client-ID".
For sanity checks, a PCP Server maintains the same CLIENT_ID value (which is used in the latest PCP request) for a given PCP Client for all mappings associated with the same internal IP address belonging to the same subscriber. Indeed, the PCP Server maintains an additional identifier denoted as subscriber-Id. A subscriber-is can be an IP address, IPv6 prefix or a subscriber identifier configured locally.
Security considerations discussed in [I-D.ietf-pcp-base] must be considered. The use of CLIENT_ID option allows to soften issues related to stale mappings.
The following PCP Option Code are to be allocated:
TBC.
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. |
| [RFC4086] | Eastlake, D., Schiller, J. and S. Crocker, "Randomness Requirements for Security", BCP 106, RFC 4086, June 2005. |
| [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. |
| [RFC6145] | Li, X., Bao, C. and F. Baker, "IP/ICMP Translation Algorithm", RFC 6145, April 2011. |
| [RFC6146] | Bagnulo, M., Matthews, P. and I. van Beijnum, "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", RFC 6146, April 2011. |