Internet DRAFT - draft-kiesel-pcp-ip-based-srv-disc
draft-kiesel-pcp-ip-based-srv-disc
PCP S. Kiesel
Internet-Draft University of Stuttgart
Intended status: Standards Track R. Penno
Expires: February 20, 2014 Cisco Systems
August 19, 2013
PCP Server Discovery based on well-known IP Address
draft-kiesel-pcp-ip-based-srv-disc-01
Abstract
The Port Control Protocol (PCP) provides a mechanism to control how
incoming packets are forwarded by upstream devices such as Network
Address Translator IPv6/IPv4 (NAT64), Network Address Translator
IPv4/IPv4 (NAT44), IPv6 and IPv4 firewall devices, and a mechanism to
reduce application keep alive traffic.
This document establishes a well-known IP address for the PCP Server
and documents how PCP clients embedded in endpoints can use it during
the discovery and regular operation phases.
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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 February 20, 2014.
Copyright Notice
Copyright (c) 2013 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
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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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. PCP Server Discovery based on well-known IP Address . . . . . 5
2.1. Well-Known PCP Server IP Address (WkPsdIPa) . . . . . . . 5
2.2. PCP Discovery Client behavior . . . . . . . . . . . . . . 5
2.3. PCP Discovery Server behavior . . . . . . . . . . . . . . 5
3. Deployment Considerations . . . . . . . . . . . . . . . . . . 6
3.1. Multiple PCP Servers, Symmetric Routing . . . . . . . . . 6
3.2. Multiple PCP Servers, Assymetric Routing . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
4.1. Registration of IPv4 Special Purpose Address . . . . . . . 8
4.2. Registration of IPv6 Special Purpose Address . . . . . . . 9
4.3. PCP Option . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1. Normative References . . . . . . . . . . . . . . . . . . . 13
7.2. Informative References . . . . . . . . . . . . . . . . . . 13
Appendix A. Problems with Other Discovery methods . . . . . . . . 15
A.1. DHCP PCP Options . . . . . . . . . . . . . . . . . . . . . 15
A.2. Default Router . . . . . . . . . . . . . . . . . . . . . . 15
A.3. User Input . . . . . . . . . . . . . . . . . . . . . . . . 15
A.4. Domain Name System Based . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
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1. Introduction
The Port Control Protocol (PCP) [I-D.ietf-pcp-base] provides a
mechanism to control how incoming packets are forwarded by upstream
devices such as Network Address Translator IPv6/IPv4 (NAT64), Network
Address Translator IPv4/IPv4 (NAT44), IPv6 and IPv4 firewall devices,
and a mechanism to reduce application keep alive traffic.
But before a PCP client can perform any of these tasks it needs to
discover one or more PCP servers. Several algorithms have been
specified that produce a suitable PCP Server address given PCP client
(i.e., the address may vary for different clients or different points
of network attachment, etc.). These approaches are based on user
input, DHCP [I-D.ietf-pcp-dhcp] or default router, which is the one
detailed in the PCP base document [I-D.ietf-pcp-base].
But unfortunately in many deployments, the first-hop router does not
run a PCP server, or DHCP cannot be used. These and other problems
are described in detail in the Appendix.Appendix A.
This document follows a different approach: it establishes a well-
known address for the PCP Server (TBD: this approach could easily be
generalized in order to discover other services as well. But this is
for further study). PCP clients are expected to send requests to
this address during the PCP Server discovery process. A PCP Server
configured with the anycast address could optionally redirect or
return a list of unicast PCP Servers to the client.
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2. PCP Server Discovery based on well-known IP Address
2.1. Well-Known PCP Server IP Address (WkPsdIPa)
IANA is requested to register a single IPv4 address 192.0.0.X (TBD)
and a single IPv6 address 2001:YYYY::ZZZZ (TBD) within the respective
Special Purpose Address Registries as the well-known IP anycast
addresses for PCP Servers. These addresses are called WkPsdIPa
(well-known PCP server discovery IP address(es)) in this document.
2.2. PCP Discovery Client behavior
PCP Clients that need to discover PCP servers should first send a PCP
request to its default router. This is important because in the case
of cascaded PCP Servers, all of them need to be discovered in order
of hop distance from the client. The PCP client then SHOULD send a
PCP request to the WkPsdIPa. PCP Clients must be prepared to receive
an error and try other discovery methods.
2.3. PCP Discovery Server behavior
PCP Server can be configured to listen on the WkPsdIPa for incoming
PCP requests.
PCP responses are sent from that same IANA-assigned address (see Page
5 of [RFC1546]).
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3. Deployment Considerations
Network operators should install one or more PCP Servers as specified
above. Depending on the network deployment scenario they may use IP
routing tables, or other suitable mechanisms to direct PCP requests
to one of these servers.
[TBD: explain in more detail] This works fine even with cascaded
access routers with NATs. After each router hop the operator may
decide whether to handle the discovery requests, e.g., using a static
routing table entry, or whether let them flow "automatically" towards
the Internet backbones using the default routing table entry.
3.1. Multiple PCP Servers, Symmetric Routing
In the case of symmetric routing all inbound and outbound packets
from a PCP client traverse the same PCP Server or controlled device.
Multiple PCP Servers sharing an anycast address in a symmetric
routing scenario are used for two purposes: ease of network
configuration and redundancy. In the case of redundancy, If there is
a network or routing change a PCP client might start interacting with
a different PCP Server sharing the same anycast address. From a PCP
Client point of view this would be the same as a PCP Server reboot
and a PCP Client could find out about it by examining the Epoch field
during the next PCP request or ANNOUNCE message.
3.2. Multiple PCP Servers, Assymetric Routing
In the case of asymmetric routing inbound packets from a PCP client
traverse a different PCP Server or controlled device than outbound
packets. If these PCP Servers are firewalls, the PCP client would
need to create mappings on both of them in order to properly
communicate with other hosts. But if these PCP Servers share an
anycast address the PCP Client will create mappings in only on, when
in fact should create mapping on both of them.
Therefore in order to support this scenario we propose a new option
for the ANNOUNCE opcode. This will allow a PCP Client to request
from a PCP Server a list of unicast IP addresses associated with
other PCP Servers. The client can then proceed to create mappings on
these PCP Servers using their unicast addresses.
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This Option:
Option Name: LIST_PCP_SRVS
Number: TBA (IANA)
Purpose: Allows a PCP Client to request from a PCP Server a list of
all PCP Servers configured
Valid for Opcodes: ANNOUNCE
Length: 0x0
May appear in: request and reply
Maximum occurrences in request: 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LIST_PCP_SRVS | Reserved | Option Length=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Reply from the PCP Server would be a list of IP addresses
Length in reply: 128 bits * number of IP addresses
Maximum occurrences in reply: as many as fit within maximum PCP message size
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LIST | Reserved | Variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| List of IP Addresses |
| |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|
Figure 1: List of PCP Servers
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4. IANA Considerations
4.1. Registration of IPv4 Special Purpose Address
IANA is requested to register a single IPv4 address in the IANA IPv4
Special Purpose Address Registry [RFC5736].
[RFC5736] itemizes some information to be recorded for all
designations:
1. The designated address prefix.
Prefix: TBD by IANA. Prefix length: /32
2. The RFC that called for the IANA address designation.
This document.
3. The date the designation was made.
TBD.
4. The date the use designation is to be terminated (if specified
as a limited-use designation).
Unlimited. No termination date.
5. The nature of the purpose of the designated address (e.g.,
unicast experiment or protocol service anycast).
protocol service anycast.
6. For experimental unicast applications and otherwise as
appropriate, the registry will also identify the entity and
related contact details to whom the address designation has been
made.
N/A.
7. The registry will also note, for each designation, the
intended routing scope of the address, indicating whether the
address is intended to be routable only in scoped, local, or
private contexts, or whether the address prefix is intended to be
routed globally.
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Typically used within a network operator's network domain, but in
principle globally routable.
8. The date in the IANA registry is the date of the IANA action,
i.e., the day IANA records the allocation.
TBD.
4.2. Registration of IPv6 Special Purpose Address
IANA is requested to register a single IPv6 address in the IANA IPv6
Special Purpose Address Block [RFC4773].
[RFC4773] itemizes some information to be recorded for all
designations:
1. The designated address prefix.
Prefix: TBD by IANA. Prefix length: /128
2. The RFC that called for the IANA address designation.
This document.
3. The date the designation was made.
TBD.
4. The date the use designation is to be terminated (if specified
as a limited-use designation).
Unlimited. No termination date.
5. The nature of the purpose of the designated address (e.g.,
unicast experiment or protocol service anycast).
protocol service anycast.
6. For experimental unicast applications and otherwise as
appropriate, the registry will also identify the entity and
related contact details to whom the address designation has been
made.
N/A.
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7. The registry will also note, for each designation, the
intended routing scope of the address, indicating whether the
address is intended to be routable only in scoped, local, or
private contexts, or whether the address prefix is intended to be
routed globally.
Typically used within a network operator's network domain, but in
principle globally routable.
8. The date in the IANA registry is the date of the IANA action,
i.e., the day IANA records the allocation.
TBD.
4.3. PCP Option
The following PCP Option should be allocated:
LIST_PCP_SRVS
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5. Security Considerations
TBD
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6. Acknowledgements
Ted Lemon for insightful DHCP discussions and Dave Thaler for
pointing out the asymmetric routing case.
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7. References
7.1. Normative References
[RFC1546] Partridge, C., Mendez, T., and W. Milliken, "Host
Anycasting Service", RFC 1546, November 1993.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2732] Hinden, R., Carpenter, B., and L. Masinter, "Format for
Literal IPv6 Addresses in URL's", RFC 2732, December 1999.
[RFC3958] Daigle, L. and A. Newton, "Domain-Based Application
Service Location Using SRV RRs and the Dynamic Delegation
Discovery Service (DDDS)", RFC 3958, January 2005.
[RFC4773] Huston, G., "Administration of the IANA Special Purpose
IPv6 Address Block", RFC 4773, December 2006.
[RFC5736] Huston, G., Cotton, M., and L. Vegoda, "IANA IPv4 Special
Purpose Address Registry", RFC 5736, January 2010.
7.2. Informative References
[DhcpRequestParams]
OpenFlow, "OpenFlow Switch Specification", February 2011,
<http://msdn.microsoft.com/en-us/library/windows/desktop/
aa363298%28v=vs.85%29.aspx>.
[I-D.chen-pcp-mobile-deployment]
Chen, G., Cao, Z., Boucadair, M., Ales, V., and L.
Thiebaut, "Analysis of Port Control Protocol in Mobile
Network", draft-chen-pcp-mobile-deployment-04 (work in
progress), July 2013.
[I-D.ietf-dhc-container-opt]
Droms, R. and R. Penno, "Container Option for Server
Configuration", draft-ietf-dhc-container-opt-07 (work in
progress), April 2013.
[I-D.ietf-pcp-base]
Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)",
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draft-ietf-pcp-base-29 (work in progress), November 2012.
[I-D.ietf-pcp-dhcp]
Boucadair, M., Penno, R., and D. Wing, "DHCP Options for
the Port Control Protocol (PCP)", draft-ietf-pcp-dhcp-08
(work in progress), August 2013.
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Appendix A. Problems with Other Discovery methods
Several algorithms have been specified that allows PCP Client to
discover the PCP Servers on a network . However, each of this
approaches has technical or operational issues that will hinder the
fast deployment of PCP.
A.1. DHCP PCP Options
There are two problems with DHCP Options: DHCP Server on Home
Gateways (HGW) and Operating Systems DHCP clients
Currently what the HGW does with the options it receives from the ISP
is not standardized in any general way. As a matter of practice, the
HGW is most likely to use its own customer-LAN-facing IP address for
the DNS server address. As for other options, it's free to offer the
same values to the client, offer no value at all, or offer its own IP
address if that makes sense, as it does (sort of) for DNS.
In scenarios where PCP Server resides on ISP network and is intended
to work with arbitrary home gateways that don't know they are being
used in a PCP context, that won't work, because there's no reason to
think that the HGW will even request the option from the DHCP server,
much less offer the value it gets from the server on the customer-
facing LAN. There is work on the DHC WG to overcome some of these
limitations [I-D.ietf-dhc-container-opt] but in terms of deployment
it also needs HGW to be upgraded.
The problems with Operating Systems is that even if DHCP PCP Option
were made available to customer-facing LAN, host stack DHCP
enhancements are required to process or request new DHCP PCP option.
One exception is Windows [DhcpRequestParams]
Finally, in the case of IPv6 there are networks where there is DHCPv6
infrastructure at all or some hosts do not have a DHCPv6 client.
A.2. Default Router
If PCP server does not reside in first hop router, whether because
subscriber has a existing home router or in the case of Wireless
Networks (3G, LTE) [I-D.chen-pcp-mobile-deployment], trying to send a
request to default router will not work.
A.3. User Input
A regular subscriber can not be expected to input IP address of PCP
Server or network domain name. Moreover, user can be at a Wi-Fi
hotspot, Hotel or related. Therefore relying on user input is not
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reliable.
A.4. Domain Name System Based
There are three separate category of problems with NAPTR [RFC3958]
1. End Points: It relies on PCP client determining the domain name
and supporting certain DNS queries
2. DNS Servers: DNS server need to be provisioned with the necessary
records
3. CPEs: CPEs might interfere with DNS queries and the DHCP domain
name option conveyed by ISP that could be used to bootstrap NAPTR
might not be relayed to home network.
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Authors' Addresses
Sebastian Kiesel
University of Stuttgart Computing Center
Allmandring 30
Stuttgart 70550
Germany
Email: ietf-pcp@skiesel.de
URI: http://www.rus.uni-stuttgart.de/nks/
Reinaldo Penno
Cisco Systems
170 West Tasman Dr
San Jose CA
USA
Email: repenno@cisco.com
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