Port Control Protocol R. Penno
Internet-Draft Juniper Networks
Intended status: Standards Track October 20, 2011
Expires: April 22, 2012
PCP Support for Multi-Zone Environments
draft-penno-pcp-zones-01
Abstract
A zone is a notion which denotes a routing instance, a set interfaces
or prefixes characterized by having a different address realm and/or
security policy. A NAT device can route packets with the same source
IP address to different zones depending on configuration policies
such as destination IP address. This functionality has been present
for many years in NAT devices from multiple vendors. PCP allows a
host to interact with a PCP-controlled NAT device and request an
external IP and port. Therefore a PCP Server that controls the NAT
device and receives a PCP request from a host needs to know from
which NAT pool to allocate an external IP address and port. This
document specifies an extension to PCP to support the zone concept.
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.
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This Internet-Draft will expire on April 22, 2012.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Problem Statement . . . . . . . . . . . . . . . . . . . . . 3
1.3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. PCP Base Support for Multiple Zones . . . . . . . . . . . . . . 4
2.1. PCP PEER Request . . . . . . . . . . . . . . . . . . . . . 4
2.2. PCP MAP Request . . . . . . . . . . . . . . . . . . . . . . 5
3. PCP Extension for Multiple Zones . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
A zone is a routing instance, set interfaces or prefixes
characterized by having a different address domain or security
policy. A NAT device is present on each zone through NAT pools which
are used to translate packet to and from a zone. The PCP protocol
allows a host to interact with a NAT device and request a external IP
and port. Since a NAT Device can route packets with the same source
IP address to different Zones depending on policy or packet match
conditions, the PCP Server that interacts with the NAT device and
receives a PCP request from a host needs to know from which NAT pool
to allocate an IP address and port.
1.1. Terminology
This document uses PCP terminology defined in [I-D.ietf-pcp-base]].
In addition the following terms are defined in this document:
o Zone: A routing instance, set of interfaces or network prefixes
that has a separate addressing domain or security policy.
o Address Domain: A collection of IP addresses. A NAT device is
present on each domain through one or more NAT pools associated
with each Zone.
1.2. Problem Statement
A PCP Server can control a NAT attached to distinct zones; each zone
is characterised by one or several address pools. In such
environment the NAT must rely on a pre-configured policy to determine
which address pool to use when handling an IP packet coming from an
internal host. An example of such policy may be to rely on the
destination IP address, DSCP value(s), protocol (e.g., SIP, RTP,
RTSP), etc.
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,-----.
,' `.
.( Zone IPTV )
,-------. .-' `. ,'
,-' Zone `-. .' `-----'
Host Access \ CGN .-' ,-------.
+----+-----+ +---+------+ .' ,' `.
|PCP Client|-------|PCP Server|.'------------(Zone Internet)
+----+-----+ +---+------+ `-. `. ,'
\ / `. `-------' \
`-. ,-' `-. ,-----. `.
`-------' `. / \ )
`-( Zone VPN-------'
\ /
`-----'
The core of the problem is that packets from the same source IP
address can be routed to any of the zones depending on match
conditions based on the 5-tuple. Moreover, sessions could be
initiated from any of these zones toward the host. These zones many
times have different addressing domains and therefore different NAT
pools. This means that packets from the host will use a different
NAT pool depending on the destination zone.
It is important to notice that zones (or similar concept) has been
present in Enteprise NAT and CGN from multiple vendors for many
years. It is the advent and interaction with PCP that has created a
need for a standardized approach.
1.3. Scope
The matching conditions that ultimately decide where to route a
packet can be very elaborate including even application layer
information. But the scope of this document is to abstract such
implementation specific approaches behind the concept of a Zone-ID.
2. PCP Base Support for Multiple Zones
Before discussing extensions to the PCP protocol in the following
sections we discuss how to support multiple zones with the current
methods present in the base PCP protocol.
2.1. PCP PEER Request
A PCP PEER request could contains the destination IP address, port
and Transport protocol of the peer the host will be trying to
communicate . In that case, if the NAT device maintains a mapping of
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zones (and associated NAT pools) to network prefixes it can choose
the appropriate NAT pool. It is important to understand that this
will only work if the policy that decides to which Zone to route
packets is only based on the information present on the PCP PEER
request.
Therefore if the PCP Client knows it is behind a NAT with zone
support, it is RECOMMENDED that it includes the remote peer's 5-tuple
in the PCP PEER request in the connect-then-lifetime case. If the
peer's 5-tuple is not present in the PCP request, the external IP and
port returned in the message is non-deterministic.
2.2. PCP MAP Request
In the case of PCP MAP request the NAT device does not know from
which zone to install a mapping and consequently from which NAT pool
to choose an external IP address and port. A FILTER Option may be
included to allow the PCP Server select the external address pool to
use. If other information than the destination IP address is used to
drive the selection of the external address pool, additional
information is required to be conveyed in the PCP MAP request (e.g.,
DSCP marking policy (see http://tools.ietf.org/html/
draft-boucadair-pcp-extensions-01#section-3).
3. PCP Extension for Multiple Zones
The proposed PCP extension is a new PCP Option that would convey the
Zone-ID. The Zone-ID is an opaque identifier that is known by the
PCP Client and the PCP-controlled NAT device. The procedure to
provision the Zone-ID is out of scope.
When the NAT device receives a PCP request with a Zone-ID, it will
use that or a derivative of it to determine the NAT pool from which
to allocate an IP address and port.
Option Name: ZONEID
Number: TBA (IANA); Mandatory to process
Purpose: It allows the client request and server indicate from
which Zone-ID the external IP:port were allocated.
Valid for Opcodes: MAP, PEER
Length: Variable
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May appear in: both
Maximum occurrences: 1
4. IANA Considerations
TBD
5. Security Considerations
Subscribers can only request ports for the specific Zone-IDs allowed
in their security profile. For example, in a typical Wireless
deployment, mobile terminals could request mappings in zones
'Internet', 'HTTP Proxy Farm', and 'Video Farm'. A PCP request that
contains a zone-id considered a security violation would be silently
dropped.
6. Acknowledgements
Thanks to Mohamed Boucadair for early review comments
7. References
7.1. Normative References
[RFC0959] Postel, J. and J. Reynolds, "File Transfer Protocol",
STD 9, RFC 959, October 1985.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2766] Tsirtsis, G. and P. Srisuresh, "Network Address
Translation - Protocol Translation (NAT-PT)", RFC 2766,
February 2000.
[RFC2960] Stewart, R., Xie, Q., Morneault, K., Sharp, C.,
Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M.,
Zhang, L., and V. Paxson, "Stream Control Transmission
Protocol", RFC 2960, October 2000.
[RFC4787] Audet, F. and C. Jennings, "Network Address Translation
(NAT) Behavioral Requirements for Unicast UDP", BCP 127,
RFC 4787, January 2007.
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[RFC4966] Aoun, C. and E. Davies, "Reasons to Move the Network
Address Translator - Protocol Translator (NAT-PT) to
Historic Status", RFC 4966, July 2007.
[RFC5382] Guha, S., Biswas, K., Ford, B., Sivakumar, S., and P.
Srisuresh, "NAT Behavioral Requirements for TCP", BCP 142,
RFC 5382, October 2008.
[RFC5508] Srisuresh, P., Ford, B., Sivakumar, S., and S. Guha, "NAT
Behavioral Requirements for ICMP", BCP 148, RFC 5508,
April 2009.
7.2. Informative References
[I-D.ietf-behave-address-format]
Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators",
draft-ietf-behave-address-format-10 (work in progress),
August 2010.
[I-D.ietf-behave-dns64]
Bagnulo, M., Sullivan, A., Matthews, P., and I. Beijnum,
"DNS64: DNS extensions for Network Address Translation
from IPv6 Clients to IPv4 Servers",
draft-ietf-behave-dns64-11 (work in progress),
October 2010.
[I-D.ietf-behave-ftp64]
Beijnum, I., "An FTP ALG for IPv6-to-IPv4 translation",
draft-ietf-behave-ftp64-12 (work in progress), July 2011.
[I-D.ietf-behave-v6v4-framework]
Baker, F., Li, X., Bao, C., and K. Yin, "Framework for
IPv4/IPv6 Translation",
draft-ietf-behave-v6v4-framework-10 (work in progress),
August 2010.
[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-pcp-base]
Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)",
draft-ietf-pcp-base-16 (work in progress), October 2011.
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[I-D.wing-behave-dns64-config]
Wing, D., "IPv6-only and Dual Stack Hosts on the Same
Network with DNS64", draft-wing-behave-dns64-config-03
(work in progress), February 2011.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment
(ICE): A Protocol for Network Address Translator (NAT)
Traversal for Offer/Answer Protocols", RFC 5245,
April 2010.
[RFC5853] Hautakorpi, J., Camarillo, G., Penfield, R., Hawrylyshen,
A., and M. Bhatia, "Requirements from Session Initiation
Protocol (SIP) Session Border Control (SBC) Deployments",
RFC 5853, April 2010.
Author's Address
Reinaldo Penno
Juniper Networks
1194 N Mathilda Avenue
Sunnyvale, California 94089
USA
Email: rpenno@juniper.net
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