PCP Working Group M. Boucadair
Internet-Draft France Telecom
Intended status: Standards Track F. Dupont
Expires: September 15, 2011 Internet Systems Consortium
R. Penno
Juniper Networks
March 14, 2011
Port Control Protocol (PCP) Failure Scenarios
draft-boucadair-pcp-failure-01
Abstract
This document identifies and analyzes several PCP failure scenarios.
A procedure to retrieve the explicit dynamic mapping(s) from the PCP
Server is proposed. This procedure relies upon the use of a new PCP
OpCode and Option: GET/NEXT.
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 September 15, 2011.
Copyright Notice
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
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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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. PCP Failure Scenarios . . . . . . . . . . . . . . . . . . . . 3
2.1. Change of the IP Address of The PCP Server . . . . . . . . 3
2.2. Application Crash . . . . . . . . . . . . . . . . . . . . 3
2.3. PCP Client Crash . . . . . . . . . . . . . . . . . . . . . 4
2.4. Change of the Internal IP Address . . . . . . . . . . . . 4
2.5. Change of the CPE WAN IP Address . . . . . . . . . . . . . 5
2.6. Restart or Failure of the PCP Server . . . . . . . . . . . 6
2.6.1. Basic Rule . . . . . . . . . . . . . . . . . . . . . . 6
2.6.2. Clear PCP Mappings . . . . . . . . . . . . . . . . . . 6
2.6.3. State Redundancy is Enabled . . . . . . . . . . . . . 6
2.6.4. Cold-Standby without State Redundancy . . . . . . . . 6
2.6.5. Anycast Redundancy Mode . . . . . . . . . . . . . . . 7
3. PCP State Synchronization: Overview . . . . . . . . . . . . . 7
4. GET/NEXT Operation . . . . . . . . . . . . . . . . . . . . . . 7
4.1. OpCode Format . . . . . . . . . . . . . . . . . . . . . . 8
4.2. OpCode-Specific Result Code . . . . . . . . . . . . . . . 9
4.3. Ordering and Equality . . . . . . . . . . . . . . . . . . 9
4.4. NEXT Option . . . . . . . . . . . . . . . . . . . . . . . 10
4.5. GET/NEXT PCP Client Theory of Operation . . . . . . . . . 12
4.6. GET/NEXT PCP Server Theory of Operation . . . . . . . . . 13
5. Flow Examples . . . . . . . . . . . . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 17
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1. Normative References . . . . . . . . . . . . . . . . . . . 18
8.2. Informative References . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
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1. Introduction
This document discusses several failure scenarios that may occur when
deploying PCP [I-D.ietf-pcp-base].
2. PCP Failure Scenarios
2.1. Change of the IP Address of The PCP Server
When a new IP address is used to reach its PCP Server, the PCP Client
MUST re-create all of its explicit dynamic mappings using the newly
discovered IP address.
The PCP Client MUST undertake the same process as per refreshing an
existing explicit dynamic mapping (see [I-D.ietf-pcp-base]); the only
difference is the PCP Requests are sent to a distinct IP address. No
specific behavior is required from the PCP Server for handling these
requests.
2.2. Application Crash
When a fatal error is encountered by an application relying on PCP to
open explicit dynamic mappings on an upstream device, and upon the
restart of that application, the PCP Client should issue appropriate
requests to refresh the explicit dynamic mappings of that application
(e.g., clear old mappings and install new ones using the new port
number used by the application).
If a distinct port number is used by the application to bound its
service (i.e., a new internal port number is to be signaled in PCP),
the PCP Server may honor the refresh requests if the per-subscriber
quota is not exceeded. A distinct external port number would be
assigned by the PCP Server due to the presence of "stale" explicit
dynamic mapping(s) associated with the "old" port number.
To avoid this inconvenience induced by stale explicit dynamic
mappings, the PCP Client MAY clear the "old" mappings before issuing
the refresh requests; but this would require the PCP Client to store
the information about the "old" port number. This can be easy to
solve if the PCP Client is embedded in the application. In some
scenarios, this is not so easy because the PCP Client may handle PCP
requests on behalf of several applications and no means to identify
the requesting application may be supported. Means to identify the
application are implementation-specific and are out of scope of this
document.
It is NOT RECOMMENDED for a PCP Client to issue a request to delete
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all the explicit dynamic mappings associated with an internal IP
address since other applications and PCP Client(s) may use the same
internal IP address to instruct their explicit dynamic mappings in
the PCP Server.
[Ed. This is in fact about the "application ID" idea. An
alternative is to implement a per host service which provides
mediation between applications and PCP (it is the only PCP Client
running on the host).]
2.3. PCP Client Crash
The PCP Client may encounter a fatal error leading to its restart.
In such case, the internal IP address and port numbers used by
requesting applications are not impacted. Therefore, the explicit
dynamic mappings as maintained by the PCP Server are accurate and
there is no need to refresh them.
On the PCP Client side, a new UDP port should be assigned to issue
PCP requests. As a consequence, if outstanding requests have been
sent to the PCP Server, the responses are likely to be lost.
If the PCP Client stores its explicit dynamic mappings in a
persistent memory, there is no need to retrieve the list of active
mappings from the PCP Server. If several PCP Clients are co-located
on the same host, related PCP mapping tables should be uniquely
distinguished (e.g., a PCP Client does not delete explicit dynamic
mappings instructed by another PCP Client.)
If the PCP Client (or the application) is crashing, it should be
allocating short PCP lifetimes until it is debugged and running
properly. If it is never debugged and never running properly, it
should continue to request short PCP lifetimes.
2.4. Change of the Internal IP Address
When a new IP address is assigned to a host embedding a PCP Client,
the PCP Client MUST install on the PCP Server all the explicit
dynamic mappings it manages, using the new assigned IP address as the
internal IP address. The hinted external port number won't be
assigned by the PCP Server since a "stale" mapping is already
instantiated by the PCP Server (but it is associated with a distinct
internal IP address).
For a host configured with several addresses, the PCP Client MUST
maintain a record about the target IP address it used when issuing
its PCP requests. If no record is maintained and upon a change of
the IP address or de-activation of an interface, the PCP-instructed
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explicit dynamic mappings are broken and inbound communications will
fail to be delivered.
Depending on the configured policies, the PCP Server may honor all or
part of the requests received from the PCP Client. Upon receipt of
the response from the PCP Server, the PCP Client MUST update its
local PCP state with the new assigned port numbers and external IP
address.
[Ed. Note: Do we need to support means to clear stale explicit
dynamic mappings first? This may have an impact if the quota is
exceed due to the presence of stale mappings.]
A PCP Client may be used to manage explicit dynamic mappings on
behalf of a third party (i.e., the PCP Client and the third party are
not co-located on the same host). If a new internal IP address is
assigned to that third party (e.g., webcam), the PCP Client SHOULD be
instructed to delete the old mapping(s) and create new one(s) using
the new assigned internal IP address. When the PCP Client is co-
located with the DHCP server (e.g., PCP Proxy [I-D.bpw-pcp-proxy],
IWF in the CP router [I-D.bpw-pcp-upnp-igd-interworking]), the state
can be updated using the state of the local DHCP server. Otherwise,
it is safe to recommend the use of static internal IP addresses if
PCP is used to configure third-party explicit dynamic mappings.
2.5. Change of the CPE WAN IP Address
The change of the IP address of the WAN interface of the CPE would
have an impact on the accuracy of the explicit dynamic mappings
instantiated in the PCP Server:
o For the DS-Lite case [I-D.ietf-softwire-dual-stack-lite]: if a new
IPv6 address is used by the B4 element when encapsulating IPv4
packets in IPv6 ones, the explicit dynamic mappings SHOULD be
refreshed: If the PCP Client is embedded in the B4, the refresh
operation is triggered by the change of the B4 IPv6 address. This
would be more complicated when the PCP Client is located in a
device behind the B4.
[Ed. Note: how an IPv4 host behind a DS-Lite CPE is aware that
a new IPv6 address is used by the B4?]
o For the NAT64 case [I-D.ietf-behave-v6v4-xlate-stateful], any
change of the assigned IPv6 prefix delegated to the CPE will be
detected by the PCP Client (because this leads to the allocation
of a new IPv6 address). The PCP Client has to undertake the
operation described in Section 2.4.
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o For the NAT444 case, similar problems are encountered because the
PCP client has no reasonable way to detect the CPE's WAN address
changed.
2.6. Restart or Failure of the PCP Server
This section covers failure scenarios encountered by the PCP Server.
2.6.1. Basic Rule
In any situation the PCP Server loses all or part of its PCP state,
the Epoch value MUST be reset when replying to received requests.
Doing so would allow PCP Client to audit its explicit dynamic mapping
table.
If the state is not lost, the PCP Server MUST NOT reset the Epoch
value returned to requesting PCP Clients.
2.6.2. Clear PCP Mappings
When a command line or a configuration change is enforced to clear
all or a subset of PCP explicit dynamic mappings maintained by the
PCP Server, the PCP Server MUST reset its Epoch to zero value.
In order to avoid all PCP Clients to update their explicit dynamic
mappings, the PCP Server SHOULD reset the Epoch to zero value only
for impacted users.
[Ed. Note: This may contradict Epoch being a global-wise
parameter and not a per-user parameter]
2.6.3. State Redundancy is Enabled
When state redundancy is enabled, the state is not lost during
failure events. Failures are therefore transparent to requesting PCP
Clients. When a backup device takes over, Epoch MUST NOT be reset to
zero.
2.6.4. Cold-Standby without State Redundancy
In this section we assume that a redundancy mechanisms is configured
between a primary PCP-controlled device and a backup one but without
activating any state synchronization for the PCP-instructed explicit
dynamic mappings between the backup and the primary devices.
If the primary PCP-controlled device fails and the backup one takes
over, the PCP Server MUST reset the Epoch to zero value. Doing so
would allow PCP Clients to detect the loss of states in the PCP
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Server and proceed to state synchronization.
2.6.5. Anycast Redundancy Mode
When an anycast-based mode is deployed (i.e., the same IP address is
used to reach several PCP Servers) for redundancy reasons, the change
of the PCP Server which handles the requests of a given PCP Client
won't be detected by that PCP Client.
Relying on the Epoch to detect the loss of state won't help in this
scenario to re-create missing explicit dynamic mappings.
Proprietary solutions MAY be envisaged to coordinate amongst
anycasted PCP Servers; otherwise the use of the anycast is NOT
RECOMMENDED.
3. PCP State Synchronization: Overview
The following sketches the state synchronization logic:
o One element (i.e., PCP Client/host/application, PCP Server, PCP
Proxy, PCP IWF) of the chain is REQUIRED to use stable storage
o If the PCP Client (resp., the PCP Server) crashes and restarts it
just have to synchronize with the PCP Server (resp., the PCP
Client);
o If both crash then one has to use stable storage and we fall back
in the previous case as soon as we know which one (the Epoch value
gives this information);
o PCP Server -> PCP Client not-disruptive synchronization requires a
GET/NEXT mechanism to retrieve the state from the PCP Server;
without this mechanism the only way to put the PCP Server in a
known state is for the PCP Client to send a delete all request, a
clearly disruptive operation.
o PCP Client -> PCP Server synchronization is done by a re-create or
refresh of the state. The PCP Client MAY retrieve the PCP Server
state in order to prevent stale explicit dynamic mappings.
4. GET/NEXT Operation
This section defines a new PCP OpCode called GET and its associated
Option NEXT.
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[Ed. Note: The NEXT name is surely not the best one.]
[Ed. Note: In http://tools.ietf.org/html/
draft-bpw-softwire-pcp-flow-examples-00#section-3, this option is
called Forwarding Entry Option.].
These PCP Opcode and Option are used by the PCP Client to retrieve an
explicit mapping or to walk through the explicit dynamic mapping
table maintained by the PCP Server for this subscriber and retrieves
a list of explicit dynamic mapping entries it instantiated.
4.1. OpCode Format
The GET OpCode payload contains a Filter used for explicit dynamic
mapping matching: only the explicit dynamic mappings of the
subscriber which match the Filter in a request are considered so
could be returned in response.
The layout of GET OpCode is shown in Figure 1.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol | Internal_AF | External_AF | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: Filter internal IP address (always 128 bits) :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: Filter external IP address (always 128 bits) :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Filter internal port | Filter external port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: GET: OpCode format
For all fields, including Address Families, the value 0 in a request
means wildcard filter/any value matches. Of course this has to be
sound: no defined port with protocol set to any, or address with AF
any.
These fields are described below:
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Protocol: Same than for MAP [I-D.ietf-pcp-base].
Internal_AF: The Address Family of the Filter internal IP address.
External_AF: The Address Family of the Filter external IP address
(same than for PEER [I-D.ietf-pcp-base]).
Reserved: 8 reserved bits, MUST be sent as 0 and MUST be ignored
when received.
Filter internal IP address: If the Internal Address Family is IPv4,
an IPv4 address (including the unspecified IPv4 address 0.0.0.0)
followed by 96 zero bits. If the Internal Address Family is IPv6,
an IPv6 address (including the unspecified IPv6 address ::).
Filter external IP address: If the External Address Family is IPv4,
an IPv4 address (including the unspecified IPv4 address 0.0.0.0)
followed by 96 zero bits. If the External Address Family is IPv6,
an IPv6 address (including the unspecified IPv6 address ::).
Filter internal port: The internal port (including 0).
Filter external port: The external port (including 0).
Responses include a bit-to-bit copy of the OpCode found in the
request.
4.2. OpCode-Specific Result Code
This OpCode defines a new specific Result Code
TBD: NONEXIST_MAP, e.g., no explicit dynamic mapping matching the
Filter was found.
4.3. Ordering and Equality
The PCP server is required to implement an order between matching
explicit dynamic mappings. The only property of this order is to be
stable: it doesn't change (*) between two GET requests with the same
Filter.
(*) "change" means two mappings are not gratuitously swapped:
expiration, renewal or creation are authorized to change the order
but they are at least expected by the PCP client.
[Ed. Note: We have two proposals for the order: lexicographical
order and lifetime order. Both work, this should be left to the
implementor.]
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Equality is defined by:
o same protocol and;
o same internal address family and;
o same external address family and;
o same internal address and;
o same external address and;
o same internal port and;
o same external port.
4.4. NEXT Option
Formal definition:
Name: NEXT
Number: at most one in requests, any in responses.
Purpose: carries a Locator in requests, matching explicit dynamic
mappings greater than the Locator in responses.
Is valid for OpCodes: GET OpCode.
Length: variable, the minimum is 11.
May appear in: both requests and responses.
Maximum occurrences: one for requests, bounded by maximum message
size for PCP responses [I-D.ietf-pcp-base].
The layout of the NEXT Option is shown in Figure 2.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol | Internal_AF | External_AF | MORE/END |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: Mapping internal IP address (always 128 bits) :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: Mapping external IP address (always 128 bits) :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mapping remaining lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mapping internal port | Mapping external port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Mapping Options :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: NEXT: Option format
In requests the NEXT Option carries a Locator: a position in the list
of explicit dynamic mappings which match the Filter. The following
two useful forms of Locators are considered:
o the "Undefined" form where the Protocol, Address Families,
Addresses, Ports fields are set to zero.
o the "Defined" form where none of the Protocol, Address Families,
Addresses and Ports is set to zero.
The new fields in a Locator (a.k.a., the NEXT Option in a GET
request) are described below:
MORE/END: The value 0 denotes "MORE" and means the response MAY
include multiple NEXT Options; a value other than 0 (1 is
RECOMMENDED) denotes "END" and means the response SHALL include at
most one NEXT Option.
Mapping remaining lifetime: MUST be sent as 0 and MUST be ignored
when received.
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Mapping Options: The Option Codes of the PCP Client wants to get in
the response. The format is the same than for the UNPROCESSED
Option [I-D.ietf-pcp-base].
In responses the NEXT Options carry the returned explicit dynamic
mappings, one per NEXT Option. The fields are described below:
Protocol: The protocol of the returned mapping.
Internal_AF: The family of the internal address of the returned
mapping.
External_AF: The family of the external address of the returned
mapping.
MORE/END: The value 0 when there are explicit dynamic mapping
matching the Filter and greater than this returned mapping; a
value other than 0 (1 is RECOMMENDED) when the return mapping is
the greatest explicit dynamic mapping matching the Filter.
Mapping internal IP address: the internal address of the returned
mapping. When the address family is IPv4 the IPv4 address is
followed by 96 zero bits.
Mapping external IP address: the external address of the returned
mapping. When the address family is IPv4 the IPv4 address is
followed by 96 zero bits.
Mapping remaining lifetime: The remaining lifetime in seconds of the
returned mapping.
Mapping internal port: the internal port of the returned mapping.
Mapping external port: the external port of the returned mapping.
Mapping Options: An embedded list of option values. Each
corresponding Option Code MUST be present in the request NEXT
Option, each option MUST be related to the returned mapping or not
related to any mapping.
4.5. GET/NEXT PCP Client Theory of Operation
GET requests without a NEXT Option have low usage but with a full
wildcard Filter they ask the PCP Server to know if it has at least
one explicit dynamic mapping for this subscriber.
GET requests with an END NEXT Option are "pure" GET: they asks for
the status and/or the remaining lifetime or options of a specific
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explicit dynamic mapping. It is recommended to use an Undefined
Locator and to use the Filter to identify the mapping.
GET requests with a MORE NEXT Option are for the whole explicit
dynamic mapping table retrieval from the PCP Server. The initial
request contains an Undefined Locator, other requests a Defined
Locator filled by a copy of the last returned mapping with the
Lifetime and Option fields reseted to the original values. An END
NEXT Option marks the end of the retrieval.
4.6. GET/NEXT PCP Server Theory of Operation
The PCP Server behavior is described below:
o on the reception of a valid GET request the ordered list of
explicit dynamic mapping of the subscriber matching the given
Filter is (conceptually) built.
o if the list is empty a NONEXIST_MAP error response is returned.
It includes no NEXT Option.
o the list is scanned to find the Locator using the Equality defined
in Section 4.3. If it is found the mappings less than the Locator
are removed from the list, so the result is a list which begins by
the mapping equals to the Locator followed by greater mappings.
o if the NEXT Option in the request is an END one, the first mapping
of the list is returned in an only NEXT option, marked END if the
list contains only this mapping, marked MORE otherwise.
o if the NEXT option in the request is a MORE one, as many as can
fit mappings are returned in order in the response, marked as MORE
but if the whole list can be returned the last is marked END.
"Returned" means to include required options when they are defined
for a mapping: if the mapping M has 3 REMOTE_PEER_FILTERs and the
REMOTE_PEER_FILTER code was in the request NEXT, the NEXT carrying M
will get the 3 REMOTE_PEER_FILTER options embedded.
5. Flow Examples
As an illustration example, let's consider the following explicit
dynamic mapping table is maintained by the PCP Server:
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+-----+--------------+----------+-----------+----------+------------+
| Pro | Internal IP | Internal | External | External | Remaining |
| | Address | Port | IP | Port | Lifetime |
| | | | Address | | |
+-----+--------------+----------+-----------+----------+------------+
| UDP | 198.51.100.1 | 25655 | 192.0.2.1 | 15659 | 1659 |
| TCP | 198.51.100.2 | 12354 | 192.0.2.1 | 32654 | 3600 |
| TCP | 198.51.100.2 | 8596 | 192.0.2.1 | 25659 | 6000 |
| UDP | 198.51.100.1 | 19856 | 192.0.2.1 | 42654 | 7200 |
| TCP | 198.51.100.1 | 15775 | 192.0.2.1 | 32652 | 9000 |
+-----+--------------+----------+-----------+----------+------------+
Table 1: Excerpt of a mapping table
As shown in Table 1, the PCP Server sorts the explicit dynamic
mapping table using the internal IP address and the remaining
lifetime.
Figure 3 illustrates the exchange that occurs when a PCP Client tries
to retrieve the information related to a non-existing explicit
dynamic mapping.
+------+ +------+
| PCP | | PCP |
|Client| |Server|
+------+ +------+
| (1) PCP GET Request |
| protocol= TCP |
| internal-ip-address= 198.51.100.1 |
| internal-port= 59864 |
| Undefined Locator |
|---------------------------------->|
| |
| (2) PCP GET Response |
| error= NONEXIST_MAP |
|<----------------------------------|
| |
Figure 3: Example of a failed GET operation
Figure 4 shows an example of a PCP Client which retrieves
successfully an existing mapping from the PCP Server.
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+------+ +------+
| PCP | | PCP |
|Client| |Server|
+------+ +------+
| (1) PCP GET Request |
| protocol= TCP |
| internal-ip-address= 198.51.100.1 |
| internal-port= 25655 |
| Undefined Locator |
|---------------------------------->|
| |
| (2) PCP GET Response |
| END |
| protocol= TCP |
| internal-ip-address= 198.51.100.1 |
| internal-port= 25655 |
| external-ip-address= 192.0.2.1 |
| external-port= 15659 |
| remaining-lifetime= 1659 |
|<----------------------------------|
| |
| (3) PCP MAP4 Request |
| protocol= TCP |
| internal-ip-address= 198.51.100.1 |
| internal-port= 25655 |
| external-ip-address= 192.0.2.1 |
| external-port= 15659 |
| requested-lifetime= 0 |
|---------------------------------->|
| |
Figure 4: Example of a successful GET operation
In reference to Figure 5, the PCP Server returns the explicit dynamic
mappings having the internal address equal to 192.0.2.1 ordered by
increasing remaining lifetime.
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+------+ +------+
| PCP | | PCP |
|Client| |Server|
+------+ +------+
| (1) PCP GET Request |
| internal-ip-address= 198.51.100.2 |
| Undefined Locator |
|---------------------------------->|
| |
| (2) PCP GET Response |
| MORE |
| protocol= TCP |
| internal-ip-address= 198.51.100.2 |
| internal-port= 12354 |
| external-ip-address= 192.0.2.1 |
| external-port= 32654 |
| remaining-lifetime= 3600 |
| END |
| protocol= TCP |
| internal-ip-address= 198.51.100.2 |
| internal-port= 8596 |
| external-ip-address= 192.0.2.1 |
| external-port= 25659 |
| remaining-lifetime= 6000 |
|<----------------------------------|
| |
Figure 5: Flow example of GET/NEXT
In reference to Figure 6, the PCP Server returns the explicit dynamic
mappings having the internal address equal to 192.0.2.2 ordered by
increasing remaining lifetime. In this example, the same internal
port is used for TCP and UDP.
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+------+ +------+
| PCP | | PCP |
|Client| |Server|
+------+ +------+
| (1) PCP GET Request |
| internal-ip-address= 198.51.100.1 |
| internal-port= 25655 |
| Undefined Locator |
|---------------------------------->|
| |
| (2) PCP GET Response |
| MORE |
| protocol= UDP |
| internal-ip-address= 198.51.100.1 |
| internal-port= 25655 |
| external-ip-address= 192.0.2.1 |
| external-port= 15659 |
| remaining-lifetime= 1659 |
| END |
| protocol= TCP |
| internal-ip-address= 198.51.100.1 |
| internal-port= 25655 |
| external-ip-address= 192.0.2.1 |
| external-port= 32652 |
| remaining-lifetime= 9000 |
|<----------------------------------|
| |
Figure 6: Flow example of GET/NEXT: same internal port number
6. Security Considerations
TBD.
[Ed. Two comments:
* About the stable storage if this scenario is possible:
1. subscriber A gets a mapping
2. the PCP Server crashes and reboots
3. subscriber B gets the same mapping
then the PCP Server MUST keep its state in a stable storage,
i.e., it MUST NOT forget mappings.
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* About GET/NEXT, typically if a PCP Client is allowed to delete
a mapping it SHOULD be allowed to retrieve it; and if it is not
allowed to delete a mapping it MUST NOT be allowed to retrieve
it.]
7. IANA Considerations
TBD. (no defined registry yet)
8. References
8.1. Normative References
[I-D.bpw-pcp-proxy]
Boucadair, M., Penno, R., Wing, D., and F. Dupont, "Port
Control Protocol (PCP) Proxy Function",
draft-bpw-pcp-proxy-00 (work in progress), March 2011.
[I-D.bpw-pcp-upnp-igd-interworking]
Boucadair, M., Penno, R., Wing, D., and F. Dupont,
"Universal Plug and Play (UPnP) Internet Gateway Device
(IGD)-Port Control Protocol (PCP) Interworking Function",
draft-bpw-pcp-upnp-igd-interworking-02 (work in progress),
February 2011.
[I-D.ietf-pcp-base]
Wing, D., Cheshire, S., Boucadair, M., Penno, R., and F.
Dupont, "Port Control Protocol (PCP)",
draft-ietf-pcp-base-06 (work in progress), February 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
8.2. Informative References
[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",
draft-ietf-behave-v6v4-xlate-stateful-12 (work in
progress), July 2010.
[I-D.ietf-softwire-dual-stack-lite]
Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", draft-ietf-softwire-dual-stack-lite-07 (work
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in progress), March 2011.
Authors' Addresses
Mohamed Boucadair
France Telecom
Rennes, 35000
France
Email: mohamed.boucadair@orange-ftgroup.com
Francis Dupont
Internet Systems Consortium
Email: fdupont@isc.org
Reinaldo Penno
Juniper Networks
1194 N Mathilda Avenue
Sunnyvale, California 94089
USA
Email: rpenno@juniper.net
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