| PCP WG | M. Boucadair |
| Internet-Draft | France Telecom |
| Intended status: Informational | March 23, 2015 |
| Expires: September 24, 2015 |
Port Control Protocol (PCP) Flow Examples
draft-boucadair-pcp-flow-examples-04
This document provides a set of examples to illustrate Port Control Protocol (PCP) operations. It is a companion document to the base PCP specification.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
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As a companion document to [RFC6887], this document provides examples to help understanding the PCP machinery and exchanged PCP messages in various usage contexts.
For more details about PCP protocol specification, the reader is invited to refer to [RFC6887].
Examples included in this document make use of the IPv4 and IPv6 address blocks for documentation purposes defined in [RFC5737] and [RFC3849].
The following figure illustrates the messages which are exchanged to create a mapping in a PCP-controlled device with MAP opcode.
+------+ +------+
| PCP | | PCP |
|Client| |Server|
+------+ +------+
| (1) PCP MAP Request |
|--------------------------------->|
| (2) PCP MAP Response |
|<---------------------------------|
| |
Figure 1: Example of creating a mapping
This example illustrates the content of exchanged PCP messages when the PCP client does not include any PCP Option in its request. In this example, the PCP server assigns the suggested port number. In reference to Figure 1, the content of exchanged PCP messages is as follows:
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Suggested External Port: 3938 Suggested External IP Address: ::ffff:0.0.0.0
Figure 2: MAP request (suggested External Port Honored by the PCP Server)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 20000 sec Epoch Time: 1250 MAP Response: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Assigned External Port: 3938 Assigned External IP Address: ::ffff:192.0.2.1
Figure 3: MAP response (suggested External Port Honored by the PCP Server)
This example illustrates the content of exchanged PCP messages when the PCP client is assigned with an IPv6 address but the remote server controls a NAT44 device. In reference to Figure 1, the content of exchanged PCP messages is as follows:
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: 2001:db8:0:0:1::1 MAP Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Suggested External Port: 3938 Suggested External IP Address: ::ffff:0.0.0.0
Figure 4: MAP request (suggested External Port Honored by the PCP Server)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 20000 sec Epoch Time: 1250 MAP Response: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Assigned External Port: 3938 Assigned External IP Address: ::ffff:192.0.2.1
Figure 5: MAP response (suggested External Port Honored by the PCP Server)
This example illustrates the content of exchanged PCP messages when the PCP client request the removal of an existing mapping.
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 0 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Suggested External Port: 3938 Assigned External IP Address: ::ffff:192.0.2.1
Figure 6: MAP request (Remove an Existing Mapping)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 0 sec Epoch Time: 1250 MAP Response: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Assigned External Port: 3938 Assigned External IP Address: ::ffff:192.0.2.1
Figure 7: MAP response (Remove an Existing Mapping)
This example illustrates the content of exchanged PCP messages when the PCP client does not include any PCP Option in its request. In this example, the PCP server does not assign the suggested external port number. In reference to Figure 1, the content of exchanged PCP messages is as follows:
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 11000 Suggested External Port: 11000 Suggested External IP Address: ::ffff:0.0.0.0
Figure 8: MAP request (Suggested External Port Not Honored by the PCP Server)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 20000 sec Epoch Time: 1250 MAP Response: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 11000 Assigned External Port: 15200 Assigned External IP Address: ::ffff:192.0.2.1
Figure 9: MAP response (Suggested External Port Not Honored by the PCP Server)
This example illustrates the content of exchanged PCP messages when the PCP client does not include any PCP Option in its request. In this example, the PCP client indicates a hinted external IP address honored by the PCP server. In reference to Figure 1, the content of exchanged PCP messages is as follows:
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Suggested External Port: 3938 Suggested External IP Address: ::ffff:192.0.2.1
Figure 10: MAP request (Suggested External IP Address)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 20000 sec Epoch Time: 1250 MAP Response: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Assigned External Port: 15200 Assigned External IP Address: ::ffff:192.0.2.1
Figure 11: MAP response (Suggested External IP Address)
Figure 12 shows a PCP server with a pool of public IPv4 addresses (192.0.2/24) and two PCP clients associated with different subscribers. The PCP clients each make a port mapping request to the PCP server which creates the mapping from its 192.0.2/24 pool.
+--------+ +------+ +--------+
| PCP | | PCP | | PCP |
|Client 1| |Server| |Client 2|
+--------+ +------+ +--------+
| (1) PCP MAP Request | |
|---------------------------->| |
| (2) PCP MAP Response | |
|<----------------------------| (a) PCP MAP Request |
| |<---------------------------|
| | (b) PCP MAP Response |
| |--------------------------->|
| | |
Figure 12: Example of creating mappings with distinct external IP addresses
In this example, the PCP clients were mapped to different public addresses as illustrated in the content of the PCP messages listed below.
The content of PCP messages exchanged between PCP client 1 and the PCP server is as follows:
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: TCP (6) Internal Port: 15333 Suggested External Port: 15333 Suggested External IP Address: ::ffff:0.0.0.0
Figure 13: MAP request (PCP Client 1)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 20000 sec Epoch Time: 1250 MAP Response: Mapping Nonce: 15685 Protocol: TCP (6) Internal Port: 15333 Assigned External Port: 12000 Assigned External IP Address: ::ffff:192.0.2.1
Figure 14: MAP response (PCP Client 1)
The content of PCP messages exchanged between PCP client 2 and the PCP server is as follows:
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.2 MAP Request: Mapping Nonce: 59869 Protocol: UDP (17) Internal Port: 12000 Suggested External Port: 12000 Suggested External IP Address: ::ffff:0.0.0.0
Figure 15: MAP request (PCP Client 2)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 20000 sec Epoch Time: 1250 MAP Response: Mapping Nonce: 59869 Protocol: UDP (17) Internal Port: 12000 Assigned External Port: 6000 Assigned External IP Address: ::ffff:192.0.2.2
Figure 16: MAP response (PCP Client 2)
CAUTION: The behavior described in this section is obsoleted by [I-D.cheshire-pcp-unsupp-family]. This section records the behavior as initially specified the base PCP specification [RFC6887].
This example illustrates the content of exchanged PCP messages when the PCP client does not include any PCP Option in its request. In this example, the PCP client indicates a distinct Mapping Nonce than the one stored by the PCP server. In reference to Figure 1, the content of exchanged PCP messages is as follows:
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 45687 Protocol: UDP (17) Internal Port: 3938 Suggested External Port: 3938 Suggested External IP Address: ::ffff:192.0.2.1
Figure 17: MAP request (Mapping Nonce Doesn't Match)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: NOT_AUTHORIZED (0x02) Lifetime: 35550 sec Epoch Time: 1300
Figure 18: MAP response (Mapping Nonce Doesn't Match)
Nonce validation checks are problematic in various scenarios as discussed in [I-D.cheshire-pcp-unsupp-family]. As a consequence, the nonce validation checks are relaxed as follows: If operating in the Simple Threat Model (Section 18.1 of the PCP specification [RFC6887]), and the internal port, protocol, internal address, and external address family match an existing explicit dynamic mapping, but the mapping nonce does not match, then the existing mapping is not modified in any way, and a valid PCP reply is returned to the client, using the client-specified nonce, reporting the external address, port, and remaining lifetime of the existing mapping. An example is shown in Figure 19 andFigure 3.
The request shown in Figure 19 matches an existing mapping (see Figure 3). Even if the nonce of the exiting mapping does not match the one indicated in the request, a positive answer is returned to the requesting PCP client without any change to the existing mapping. The nonce of the existing mapping (i.e., 15685) is not returned in the response.
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 45687 Protocol: UDP (17) Internal Port: 3938 Suggested External Port: 3938 Suggested External IP Address: ::ffff:192.0.2.1
Figure 19: MAP request
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 10000 sec Epoch Time: 3500 MAP Response: Mapping Nonce: 45687 Protocol: UDP (17) Internal Port: 3938 Assigned External Port: 3938 Assigned External IP Address: ::ffff:192.0.2.1
Figure 20: MAP response
This flow shows an example of the content of PCP messages that will be exchanged to create a mapping in a PCP-controlled device. In this example, the PCP client indicates a requested external UDP port number and also a PREFER_FAILURE Option. In this example, we suppose the requested port can be honored by the PCP server. In reference to Figure 1, the content of exchanged PCP messages is as follows:
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 1234 Suggested External Port: 12536 Suggested External IP Address: ::ffff:0.0.0.0 Option Code: PREFER_FAILURE (0x02) Option Length: 0 bytes Data: (NULL)
Figure 21: MAP request ( PREFER_FAILURE Option: Requested Port is Honored)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 36000 sec Epoch Time: 1250 MAP Response: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 1234 Assigned External Port: 12536 Assigned External IP Address: ::ffff:192.0.2.1
Figure 22: MAP response ( PREFER_FAILURE Option: Requested Port is Honored)
This flow shows an example of the content of PCP messages that will be exchanged to create a mapping in a PCP-controlled device. In this example, the PCP client indicates a requested external UDP port number and also a PREFER_FAILURE Option. In this example, we suppose the requested port cannot be honored by the PCP server. In reference to Figure 1, the content of exchanged PCP messages is as follows:
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 1234 Suggested External Port: 1234 Suggested External IP Address: ::ffff:0.0.0.0 Option Code: PREFER_FAILURE (0x02) Option Length: 0 bytes Data: (NULL)
Figure 23: MAP request (PREFER_FAILURE Option: Requested Port is not Honored)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: CANNOT_PROVIDE_EXTERNAL (0x11) Lifetime: 1560 sec Epoch Time: 1300
Figure 24: MAP response (PREFER_FAILURE Option: Requested Port is not Honored)
The presence of PREFER_FAILURE option in a request may have negative impact on an application which does not require it. Figure 25 shows two examples:
(1) PREFER_FAILURE Option (2) No PREFER_FAILURE Option
+------+ +------+ +------+ +------+
| PCP | | PCP | | PCP | | PCP |
|Client| |Server| |Client| |Server|
+------+ +------+ +------+ +------+
| PCP MAP Request | | PCP MAP Request |
|Suggested External Port=8080| |Suggested External Port=8080|
| PREFER_FAILURE | |--------------------------->|
|--------------------------->| | |
| PCP MAP Response | | PCP MAP Response |
| CANNOT_PROVIDE_EXTERNAL | |Assigned External Port=6598 |
|<---------------------------| |<---------------------------|
| | | TCP SYN |
| PCP MAP Request | |--------------------------->|
|Suggested External Port=5485|
| PREFER_FAILURE |
|--------------------------->|
| PCP MAP Response |
| CANNOT_PROVIDE_EXTERNAL |
|<---------------------------|
....
| PCP MAP Request |
|Suggested External Port=6591|
| PREFER_FAILURE |
|--------------------------->|
| PCP MAP Response |
| CANNOT_PROVIDE_EXTERNAL |
|<---------------------------|
Figure 25: Negative Impact of the mis-usage of PREFER_FAILURE option
This example illustrates the content of exchanged PCP messages when the PCP client requests a mapping which matches an existing implicit dynamic mapping (see Figure 26). In this example, the PCP-Controlled device assigns 10000 as external port number when translating the packet from the client having with source port set to 1234.
This behavior is specified in Section 11.3 of [RFC6887].
+------+ +------+
| PCP | | PCP |
|Client| |Server|
+------+ +------+
| (a) TCP SYN(src:1234) |
|--------------------------------->|
| (1) PCP MAP Request |
|--------------------------------->|
| (2) PCP MAP Response |
|<---------------------------------|
| |
Figure 26: Example of creating a mapping
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: TCP (0x06) Internal Port: 1234 Suggested External Port: 3938 Suggested External IP Address: ::ffff:0.0.0.0
Figure 27: MAP request (Existing Implicit Mapping)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 20000 sec Epoch Time: 1250 MAP Response: Mapping Nonce: 15685 Protocol: TCP (0x06) Internal Port: 1234 Assigned External Port: 10000 Assigned External IP Address: ::ffff:192.0.2.1
Figure 28: MAP response (Existing Implicit Mapping)
Figure 29 shows an example illustrating the impact of requesting the deletion of a mapping in the presence of traffic originated from the client. In this example, the PCP server does not remove the requested mapping immediately; the returned lifetime is set to the remaining lifetime.
This behavior is specified in Section 15 of [RFC6887].
+------+ +---------------------+
| PCP | | PCP server |
|Client| |PCP-Controlled Device|
+------+ +---------------------+
| |
|=========Traffic==================|===========>
| PCP MAP Request (Lifetime=0) |
|--------------------------------->|
| PCP MAP Response (Lifetime= |
| remaining idle-timeout) |
|<---------------------------------|
|<========Traffic==================|<==========
| |
Figure 29: Shortening a Mapping Lifetime in the Presence of Client-Originated Traffic
This example illustrates the content of the PCP MAP request to create a mapping for all incoming traffic of a given protocol (UDP is used in this example).
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 0 Suggested External Port: 0 Suggested External IP Address: ::ffff:0.0.0.0
Figure 30: MAP request (Create a mapping for all incoming traffic of a given protocol)
The PCP server may honor the request or reject it by sending UNSUPP_PROTOCOL (0x09) error.
This example illustrates the content of the PCP MAP request to create a mapping for the traffic of all protocols.
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: ANY (0) Internal Port: 0 Suggested External Port: 0 Suggested External IP Address: ::ffff:0.0.0.0
Figure 31: MAP request (Create a mapping for all protocols)
The PCP server may honor the request or reject it by sending UNSUPP_PROTOCOL (0x09) error.
This flow shows an example of the content of PCP messages that will be exchanged when a malformed request is received by the PCP server. In this example, the Protocol field is set to null.
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 45698 Protocol: ANY (0) Internal Port: 5698 Suggested External Port: 3938 Suggested External IP Address: ::ffff:0.0.0.0 Option Code: PREFER_FAILURE (0x02) Option Length: 0 bytes Data: (NULL)
Figure 32: MAP request (Malformed Request)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: MALFORMED_REQUEST (0x02) Lifetime: 0 sec Epoch Time: 1300
Figure 33: MAP response (Malformed Request)
This flow shows an example of the content of PCP messages that will be exchanged when a per-user quota is reached. A short lifetime is returned so that the client may retry and see if the request can be honored because another state has been removed.
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 45698 Protocol: UDP (17) Internal Port: 8695 Suggested External Port: 3938 Suggested External IP Address: ::ffff:0.0.0.0 Option Code: PREFER_FAILURE (0x02) Option Length: 0 bytes Data: (NULL)
Figure 34: MAP request (Exceeded Port Quota)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: USER_EX_QUOTA (10) Lifetime: 300 sec Epoch Time: 1300
Figure 35: MAP response (Exceeded Port Quota)
This flow shows an example of the content of PCP messages that will be exchanged when the requested external address family is not supported by the PCP server. In this example, IPv6 is indicated as the requested AF. The PCP server answers with an UNSUPP_FAMILY (14) error as defined in [I-D.cheshire-pcp-unsupp-family].
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 45698 Protocol: UDP (17) Internal Port: 8695 Suggested External Port: 3938 Suggested External IP Address: ::
Figure 36: MAP request (Unsupported Address Family)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: UNSUPP_FAMILY (14) Lifetime: 0 sec Epoch Time: 1300
Figure 37: MAP response (Unsupported Address Family)
This flow shows an example of the content of PCP messages that will be exchanged when the requested port is not supported by the PCP server. In this example, SCTP is indicated as the requested protocol.
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 45698 Protocol: SCTP (132) Internal Port: 8695 Suggested External Port: 3938 Suggested External IP Address: ::ffff:0.0.0.0
Figure 38: MAP request (Unsupported Protocol)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: UNSUPP_PROTOCOL (9) Lifetime: 0 sec Epoch Time: 1300
Figure 39: MAP response (Unsupported Protocol)
Suppose the client has instructed a UDP mapping for port 3938 (assigned external port is 15000 and assigned external IPv4 address is: 192.0.2.1). Upon a change of a state: e.g., change of the external IP Address, the PCP server issues an unsolicited MAP response. The content of the MAP response sent by the PCP server is shown below. The PCP client is now aware of the new assigned external IP address.
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 20000 sec Epoch Time: 1250 MAP Response: Mapping Nonce: 15685 Protocol: TCP (0x06) Internal Port: 1234 Assigned External Port: 10000 Assigned External IP Address: ::ffff:192.0.2.2
Figure 40: Unsolicited MAP Response
An example of mapping repair is shown in Figure 41.
+------+ +------+
| PCP | | PCP |
|Client| |Server|
+------+ +------+
| (1) PCP ANNOUNCE |
|<----------------------------|
| (2) PCP MAP REQUEST |
|---------------------------->|
| (3) PCP MAP RESPONSE |
|<----------------------------|
| |
Figure 41: Flow Example of a PING/PONG exchange: Check the availability of the PCP Server
Version: 2 R bit: Response (1) opcode: ANNOUNCE (0x00) Result Code: 0 Lifetime: 0 sec Epoch Time: 0
Figure 42: Unsolicited ANNOUNCE
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 11000 Assigned External Port: 15200 Assigned External IP Address: ::ffff:192.0.2.1
Figure 43: MAP request (Mapping Repair)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 20000 sec Epoch Time: 10 MAP Response: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 11000 Assigned External Port: 15200 Assigned External IP Address: ::ffff:192.0.2.1
Figure 44: MAP response (Mapping Repair)
Let us suppose a PCP-unaware NAT is located between the PCP server and the PCP client. An example of PCP MAP request issued by the PCP client is shown below.
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 11000 Assigned External Port: 15200 Assigned External IP Address: ::ffff:0.0.0.0
Figure 45: MAP request (NAT Detect)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: ADDRESS_MISMATCH (12) Lifetime: 0 sec Epoch Time: 36000
Figure 46: MAP Response (NAT Detect)
This behavior is specified in Section 8.2 of [RFC6887].
In order to retrieve the IP address used on the external side of the PCP-controlled device, the PCP client sends a short-lived mapping (e.g., Discard service (TCP/9 or UDP/9) or other port). The returned IP address can be displayed by any application requiring such information.
Version: 2 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 5 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 9 Suggested External Port: 9 Suggested External IP Address: ::ffff:0.0.0.0
Figure 47: MAP request (Retrieve the External IP Address)
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: 0 Lifetime: 60 sec Epoch Time: 1250 MAP Response: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 9 Suggested External Port: 9 Assigned External IP Address: ::ffff:192.0.2.1
Figure 48: MAP Response (Retrieve the External IP Address)
This behavior is specified in Section 11.6 of [RFC6887].
These examples follow the behavior specified in Section 13.1 of [RFC6887].
The following messages are exchanged when the THIRD_PARTY option is enabled in the PCP server side. In this example the PCP client creates a mapping for the host assigned with 198.51.100.2.
Version: 2
R bit: Request (0)
opcode: MAP (0x01)
Requested Lifetime: 36000 sec
PCP client's IP Address: ::ffff:198.51.100.1
MAP Request:
Mapping Nonce: 16584
Protocol: UDP (17)
Internal Port: 8080
Suggested External Port: 8080
Suggested External IP Address: ::ffff:0.0.0.0
Option Code: THIRD_PARTY (0x01) Option Length: 16 bytes Data:
::ffff:198.51.100.2
Figure 49: MAP request with THIRD_PARTY
Version: 2
R bit: Response (1)
opcode: MAP (0x01)
Result Code: 0
Lifetime: 20000 sec
Epoch Time: 1250
MAP Response:
Mapping Nonce: 16584
Protocol: UDP (17)
Internal Port: 8080
Assigned External Port: 15000
Assigned External IP Address: ::ffff:161.105.194.14
Option Code: THIRD_PARTY (0x01) Option Length: 16 bytes Data:
::ffff:198.51.100.2
Figure 50: MAP Response with THIRD_PARTY
The following messages are exchanged when the THIRD_PARTY option is disabled in the PCP server side. In this example the PCP client tries to create a mapping for the host assigned with 198.51.100.2.
Version: 2
R bit: Request (0)
opcode: MAP (0x01)
Requested Lifetime: 36000 sec
PCP client's IP Address: ::ffff:198.51.100.1
MAP Request:
Mapping Nonce: 16584
Protocol: UDP (17)
Internal Port: 8080
Suggested External Port: 8080
Suggested External IP Address: ::ffff:0.0.0.0
Option Code: THIRD_PARTY (0x01) Option Length: 16 bytes Data:
::ffff:198.51.100.2
Figure 51: MAP request with THIRD_PARTY
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: UNSUPP_OPTION (0x05) Lifetime: 0 sec Epoch Time: 1562
Figure 52: MAP Response with THIRD_PARTY
In this example the PCP client inserts a THIRD_PARTY option which include the IP address of the PCP client.
Version: 2
R bit: Request (0)
opcode: MAP (0x01)
Requested Lifetime: 36000 sec
PCP client's IP Address: ::ffff:198.51.100.1
MAP Request:
Mapping Nonce: 16584
Protocol: UDP (17)
Internal Port: 8080
Suggested External Port: 8080
Suggested External IP Address: ::ffff:0.0.0.0
Option Code: THIRD_PARTY (0x01) Option Length: 16 bytes Data:
::ffff:198.51.100.1
Figure 53: MAP request with THIRD_PARTY
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: MALFORMED_REQUEST (0x03) Lifetime: 0 sec Epoch Time: 1562
Figure 54: MAP Response with THIRD_PARTY
These examples follow the behavior specified in Section 13.3 of [RFC6887].
This example illustrates the content of exchanged PCP messages when the PCP client wants to receive traffic only from 192.0.2.200:5968. In reference to Figure 1, the content of exchanged PCP messages is as follows:
Version: 2
R bit: Request (0)
opcode: MAP (0x01)
Requested Lifetime: 36000 sec
PCP client's IP Address: ::ffff:198.51.100.1
MAP Request:
Mapping Nonce: 15685
Protocol: UDP (17)
Internal Port: 3938
Suggested External Port: 3938
Suggested External IP Address: ::ffff:0.0.0.0
Option Code: FILTER (0x03) Option Length: 20 bytes Data:
Prefix Length: 128
Remote Peer Port: 5968
Remote Peer IP Address: ::ffff:192.0.2.200
Figure 55: MAP request (Basic Filter Usage)
Version: 2
R bit: Response (1)
opcode: MAP (0x01)
Result Code: 0
Lifetime: 20000 sec
Epoch Time: 1250
MAP Response:
Mapping Nonce: 15685
Protocol: UDP (17)
Internal Port: 3938
Assigned External Port: 3938
Assigned External IP Address: ::ffff:192.0.2.1
Option Code: FILTER (0x03) Option Length: 20 bytes Data:
Prefix Length: 128
Remote Peer Port: 5968
Remote Peer IP Address: ::ffff:192.0.2.200
Figure 56: MAP Response (Basic Filter Usage)
This example illustrates the content of exchanged PCP messages when the PCP client wants to remove all filters. In reference to Figure 1, the content of exchanged PCP messages is as follows:
Version: 2
R bit: Request (0)
opcode: MAP (0x01)
Requested Lifetime: 36000 sec
PCP client's IP Address: ::ffff:198.51.100.1
MAP Request:
Mapping Nonce: 15685
Protocol: UDP (17)
Internal Port: 3938
Suggested External Port: 3938
Suggested External IP Address: ::ffff:0.0.0.0
Option Code: FILTER (0x03) Option Length: 20 bytes Data:
Prefix Length: 0
Remote Peer Port: 0
Remote Peer IP Address: ::ffff:0:0
Figure 57: MAP request (Remove All Filters)
Version: 2
R bit: Response (1)
opcode: MAP (0x01)
Result Code: 0
Lifetime: 20000 sec
Epoch Time: 1250
MAP Response:
Mapping Nonce: 15685
Protocol: UDP (17)
Internal Port: 3938
Assigned External Port: 3938
Assigned External IP Address: ::ffff:192.0.2.1
Option Code: FILTER (0x03) Option Length: 20 bytes Data:
Prefix Length: 0
Remote Peer Port: 0
Remote Peer IP Address: ::ffff:0:0
Figure 58: MAP response (Remove All Filters)
This example illustrates the content of exchanged PCP messages when the PCP client wants to change an existing filter. In reference to Figure 1, the content of exchanged PCP messages is as follows:
Version: 2
R bit: Request (0)
opcode: MAP (0x01)
Requested Lifetime: 36000 sec
PCP client's IP Address: ::ffff:198.51.100.1
MAP Request:
Mapping Nonce: 15685
Protocol: UDP (17)
Internal Port: 3938
Suggested External Port: 3938
Suggested External IP Address: ::ffff:0.0.0.0
Option Code: FILTER (0x03) Option Length: 20 bytes Data:
Prefix Length: 0
Remote Peer Port: 0
Remote Peer IP Address: ::ffff:0:0
Option Code: FILTER (0x03) Option Length: 20 bytes Data:
Prefix Length: 128
Remote Peer Port: 5968
Remote Peer IP Address: ::ffff:192.0.2.201
Figure 59: MAP request (Change an Existing Filter)
In this example, the PCP client issues a PCP ANNOUNCE request to a PCP server. Once received by the PCP server, since it is configured to reply to such request, it sends back a PCP ANNOUNCE response. This procedure can be used to retrieve the Epoch time.
+------+ +------+
| PCP | | PCP |
|Client| |Server|
+------+ +------+
| (1) PCP ANNOUNCE REQUEST |
|---------------------------->|
| (2) PCP ANNOUNCE RESPONSE |
|<----------------------------|
| |
Figure 60: Flow example of a PING/PONG exchange: Check the availability of the PCP server
Version: 2 R bit: Request (0) opcode: ANNOUNCE (0x00) Requested Lifetime: 0 sec PCP client's IP Address: ::ffff:198.51.100.1
Figure 61: ANNOUNCE request (Assess the Reachability of the PCP Server)
Version: 2 R bit: Response (1) opcode: ANNOUNCE (0x00) Result Code: 0 Lifetime: 0 sec Epoch Time: 3600
Figure 62: ANNOUNCE response (Assess the Reachability of the PCP Server)
The following figure illustrates the messages which are exchanged when PEER opcode is used:
+------+ +------+
| PCP | | PCP |
|Client| |Server|
+------+ +------+
| (1) PCP PEER Request |
|--------------------------------->|
| (2) PCP PEER Response |
|<---------------------------------|
| |
Figure 63: Typical usage of PEER message
Examples listed below follow the behavior specified in Section 12.2 and Section 12.3 of [RFC6887].
In reference to Figure 63, the content of exchanged PEER messages when no mapping is maintained by the PCP server for the indicated external port number:
Version: 2 R bit: Request (0) opcode: PEER (0x02) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 PEER Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Suggested External Port: 3938 Suggested External IP Address: ::ffff:0.0.0.0 Remote Peer Port: 12456 Remote IP Address: ::ffff:198.51.100.2
Figure 64: PEER request (No Mapping Exists for the Internal Port Number)
Version: 2 R bit: Response (1) opcode: PEER (0x02) Result Code: 0 Lifetime: 20000 sec Epoch Time: 1250 PEER Response: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Assigned External Port: 3938 Assigned External IP Address: ::ffff:192.0.2.1 Remote Peer Port: 12456 Remote IP Address: ::ffff:198.51.100.2
Figure 65: PEER response (No Mapping Exists for the Internal Port Number)
In reference to Figure 63, the content of exchanged PEER messages when a mapping is maintained by the PCP server for the indicated external port number:
Version: 2 R bit: Request (0) opcode: PEER (0x02) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 PEER Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Suggested External Port: 3938 Suggested External IP Address: ::ffff:0.0.0.0 Remote Peer Port: 12456 Remote IP Address: ::ffff:198.51.100.2
Figure 66: PEER request (A Mapping Exists for the External Port Number)
Version: 2 R bit: Response (1) opcode: PEER (0x02) Result Code: CANNOT_PROVIDE_EXTERNAL Lifetime: 0 sec Epoch Time: 36000
Figure 67: PEER response (A Mapping Exists for the External Port Number)
In reference to Figure 63, the content of exchanged PEER messages when the suggested external IP address does not match an existing mapping is shown below:
Version: 2 R bit: Request (0) opcode: PEER (0x02) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 PEER Request: Mapping Nonce: 15685 Protocol: UDP (17) Internal Port: 3938 Suggested External Port: 3938 Suggested External IP Address: ::ffff:192.0.2.5 Remote Peer Port: 12456 Remote IP Address: ::ffff:198.51.100.2
Figure 68: PEER request (External IP Address Cannot be Honored)
Version: 2 R bit: Response (1) opcode: PEER (0x02) Result Code: CANNOT_PROVIDE_EXTERNAL Lifetime: 0 sec Epoch Time: 36000
Figure 69: PEER response (External IP Address Cannot be Honored)
In reference to Figure 70, the content of exchanged PEER messages to extend the lifetime of a mapping.
+------+ +------+
| PCP | | PCP |
|Client| |Server|
+------+ +------+
| (a) TCP SYN(src:3938) |
|--------------------------------->|
| (1) PCP PEER Request |
|--------------------------------->|
| (2) PCP PEER Response |
|<---------------------------------|
| |
Figure 70: Example of creating a mapping
Version: 2 R bit: Request (0) opcode: PEER (0x02) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 PEER Request: Mapping Nonce: 15685 Protocol: TCP (6) Internal Port: 3938 Suggested External Port: 0 Suggested External IP Address: ::ffff:0.0.0.0 Remote Peer Port: 12456 Remote IP Address: ::ffff:198.51.100.2
Figure 71: PEER request (Extend the Lifetime)
Version: 2 R bit: Response (1) opcode: PEER (0x02) Result Code: 0 Lifetime: 20000 sec Epoch Time: 1250 PEER Response: Mapping Nonce: 15685 Protocol: TCP (6) Internal Port: 3938 Assigned External Port: 11000 Assigned External IP Address: ::ffff:192.0.2.1 Remote Peer Port: 12456 Remote IP Address: ::ffff:198.51.100.2
Figure 72: PEER response (Extend the Lifetime)
In reference to Figure 70, the content of exchanged PEER messages to learn the lifetime of a mapping is shown below:
Version: 2 R bit: Request (0) opcode: PEER (0x02) Requested Lifetime: 5 sec PCP client's IP Address: ::ffff:198.51.100.1 PEER Request: Mapping Nonce: 15685 Protocol: TCP (6) Internal Port: 3938 Suggested External Port: 0 Suggested External IP Address: ::ffff:0.0.0.0 Remote Peer Port: 12456 Remote IP Address: ::ffff:198.51.100.2
Figure 73: PEER request (Learn the Lifetime of a Mapping)
Version: 2 R bit: Response (1) opcode: PEER (0x02) Result Code: 0 Lifetime: 20000 sec Epoch Time: 1250 PEER Response: Mapping Nonce: 15685 Protocol: TCP (6) Internal Port: 3938 Assigned External Port: 11000 Assigned External IP Address: ::ffff:192.0.2.1 Remote Peer Port: 12456 Remote IP Address: ::ffff:198.51.100.2
Figure 74: PEER response (Learn the Lifetime of a Mapping)
The following exchange occurs between a PCP client that supports PCP version 1 and the PCP server that supports PCP version 2.
Version: 1 R bit: Request (0) opcode: MAP (0x01) Requested Lifetime: 36000 sec PCP client's IP Address: ::ffff:198.51.100.1 MAP Request: Protocol: UDP (17) Internal Port: 3938 Suggested External Port: 3938 Suggested External IP Address: ::ffff:0.0.0.0
Figure 75: MAP request with Version 1
Version: 2 R bit: Response (1) opcode: MAP (0x01) Result Code: UNSUPP_VERSION (1) Lifetime: 0 sec Epoch Time: 3600
Figure 76: MAP response (Unsupported Version)
Version negotiation is specified in Section 9 of [RFC6887].
PCP security considerations are discussed in [RFC6887].
This document has no IANA actions.
Many thanks to C. Jacquenet and D. Wing for the comments.
| [RFC3849] | Huston, G., Lord, A. and P. Smith, "IPv6 Address Prefix Reserved for Documentation", RFC 3849, July 2004. |
| [RFC5737] | Arkko, J., Cotton, M. and L. Vegoda, "IPv4 Address Blocks Reserved for Documentation", RFC 5737, January 2010. |
| [RFC6887] | Wing, D., Cheshire, S., Boucadair, M., Penno, R. and P. Selkirk, "Port Control Protocol (PCP)", RFC 6887, April 2013. |
| [RFC7220] | Boucadair, M., Penno, R. and D. Wing, "Description Option for the Port Control Protocol (PCP)", RFC 7220, May 2014. |
| [RFC7225] | Boucadair, M., "Discovering NAT64 IPv6 Prefixes Using the Port Control Protocol (PCP)", RFC 7225, May 2014. |
| [I-D.cheshire-pcp-unsupp-family] | Cheshire, S. and S. Perreault, "Updates to the PCP Specification", Internet-Draft draft-cheshire-pcp-unsupp-family-06, October 2013. |