draft-ietf-opsawg-lsn-deployment-05.txt   draft-ietf-opsawg-lsn-deployment-06.txt 
OPSAWG V. Kuarsingh, Ed. OPSAWG V. Kuarsingh, Ed.
Internet-Draft J. Cianfarani Internet-Draft J. Cianfarani
Intended status: Informational Rogers Communications Intended status: Informational Rogers Communications
Expires: July 27, 2014 January 23, 2014 Expires: October 15, 2014 April 13, 2014
CGN Deployment with BGP/MPLS IP VPNs CGN Deployment with BGP/MPLS IP VPNs
draft-ietf-opsawg-lsn-deployment-05 draft-ietf-opsawg-lsn-deployment-06
Abstract Abstract
This document specifies a framework to integrate a Network Address This document specifies a framework to integrate a Network Address
Translation layer into an operator's network to function as a Carrier Translation layer into an operator's network to function as a Carrier
Grade NAT (also known as CGN or Large Scale NAT). The CGN Grade NAT (also known as CGN or Large Scale NAT). The CGN
infrastructure will often form a NAT444 environment as the subscriber infrastructure will often form a NAT444 environment as the subscriber
home network will likely also maintain a subscriber side NAT home network will likely also maintain a subscriber side NAT
function. Exhaustion of the IPv4 address pool is a major driver function. Exhaustion of the IPv4 address pool is a major driver
compelling some operators to implement CGN. Although operators may compelling some operators to implement CGN. Although operators may
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term needs may not be satisfied with an IPv6 deployment alone. This term needs may not be satisfied with an IPv6 deployment alone. This
document provides a practical integration model which allows the CGN document provides a practical integration model which allows the CGN
platform to be integrated into the network, meeting the connectivity platform to be integrated into the network, meeting the connectivity
needs of the subscriber while being mindful of not disrupting needs of the subscriber while being mindful of not disrupting
existing services and meeting the technical challenges that CGN existing services and meeting the technical challenges that CGN
brings. The model included in this document utilizes BGP/MPLS IP brings. The model included in this document utilizes BGP/MPLS IP
VPNs which allow for virtual routing separation helping ease the CGNs VPNs which allow for virtual routing separation helping ease the CGNs
impact on the network. This document does not intend to defend the impact on the network. This document does not intend to defend the
merits of CGN. merits of CGN.
Status of this Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 27, 2014. This Internet-Draft will expire on October 15, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
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(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terms . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terms . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Existing Network Considerations . . . . . . . . . . . . . . . 5 2. Existing Network Considerations . . . . . . . . . . . . . . . 4
3. CGN Network Deployment Requirements . . . . . . . . . . . . . 5 3. CGN Network Deployment Requirements . . . . . . . . . . . . . 4
3.1. Centralized versus Distributed Deployment . . . . . . . . 6 3.1. Centralized versus Distributed Deployment . . . . . . . . 5
3.2. CGN and Traditional IPv4 Service Co-existence . . . . . . 7 3.2. CGN and Traditional IPv4 Service Co-existence . . . . . . 6
3.3. CGN By-Pass . . . . . . . . . . . . . . . . . . . . . . . 7 3.3. CGN By-Pass . . . . . . . . . . . . . . . . . . . . . . . 6
3.4. Routing Plane Separation . . . . . . . . . . . . . . . . . 8 3.4. Routing Plane Separation . . . . . . . . . . . . . . . . 7
3.5. Flexible Deployment Options . . . . . . . . . . . . . . . 8 3.5. Flexible Deployment Options . . . . . . . . . . . . . . . 7
3.6. IPv4 Overlap Space . . . . . . . . . . . . . . . . . . . . 8 3.6. IPv4 Overlap Space . . . . . . . . . . . . . . . . . . . 7
3.7. Transactional Logging for CGN Systems . . . . . . . . . . 9 3.7. Transactional Logging for CGN Systems . . . . . . . . . . 8
3.8. Base CGN Requirements . . . . . . . . . . . . . . . . . . 9 3.8. Base CGN Requirements . . . . . . . . . . . . . . . . . . 8
4. BGP/MPLS IP VPN based CGN Framework . . . . . . . . . . . . . 9 4. BGP/MPLS IP VPN based CGN Framework . . . . . . . . . . . . . 8
4.1. Service Separation . . . . . . . . . . . . . . . . . . . . 11 4.1. Service Separation . . . . . . . . . . . . . . . . . . . 10
4.2. Internal Service Delivery . . . . . . . . . . . . . . . . 12 4.2. Internal Service Delivery . . . . . . . . . . . . . . . . 11
4.2.1. Dual Stack Operation . . . . . . . . . . . . . . . . . 14 4.2.1. Dual Stack Operation . . . . . . . . . . . . . . . . 13
4.3. Deployment Flexibility . . . . . . . . . . . . . . . . . . 16 4.3. Deployment Flexibility . . . . . . . . . . . . . . . . . 15
4.4. Comparison of BGP/MPLS IP VPN Option versus other CGN 4.4. Comparison of BGP/MPLS IP VPN Option versus other CGN
Attachment Options . . . . . . . . . . . . . . . . . . . . 16 Attachment Options . . . . . . . . . . . . . . . . . . . 15
4.4.1. Policy Based Routing . . . . . . . . . . . . . . . . . 16 4.4.1. Policy Based Routing . . . . . . . . . . . . . . . . 15
4.4.2. Traffic Engineering . . . . . . . . . . . . . . . . . 17 4.4.2. Traffic Engineering . . . . . . . . . . . . . . . . . 16
4.4.3. Multiple Routing Topologies . . . . . . . . . . . . . 17 4.4.3. Multiple Routing Topologies . . . . . . . . . . . . . 16
4.5. Multicast Considerations . . . . . . . . . . . . . . . . . 17 4.5. Multicast Considerations . . . . . . . . . . . . . . . . 16
5. Experiences . . . . . . . . . . . . . . . . . . . . . . . . . 17 5. Experiences . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.1. Basic Integration and Requirements Support . . . . . . . . 17 5.1. Basic Integration and Requirements Support . . . . . . . 16
5.2. Performance . . . . . . . . . . . . . . . . . . . . . . . 18 5.2. Performance . . . . . . . . . . . . . . . . . . . . . . . 17
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
7. Security Considerations . . . . . . . . . . . . . . . . . . . 18 7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
8. BGP/MPLS IP VPN CGN Framework Discussion . . . . . . . . . . . 18 8. BGP/MPLS IP VPN CGN Framework Discussion . . . . . . . . . . 17
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.1. Normative References . . . . . . . . . . . . . . . . . . . 19 10.1. Normative References . . . . . . . . . . . . . . . . . . 18
10.2. Informative References . . . . . . . . . . . . . . . . . . 19 10.2. Informative References . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
Operators are faced with near term IPv4 address exhaustion Operators are faced with near term IPv4 address exhaustion
challenges. Many operators may not have a sufficient amount of IPv4 challenges. Many operators may not have a sufficient amount of IPv4
addresses in the future to satisfy the needs of their growing addresses in the future to satisfy the needs of their growing
subscriber base. This challenge may also be present before or during subscriber base. This challenge may also be present before or during
an active transition to IPv6 somewhat complicating the overall an active transition to IPv6 somewhat complicating the overall
problem space. problem space.
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extend possible; extend possible;
Other requirements may be assessed on a operator-by-operator basis, Other requirements may be assessed on a operator-by-operator basis,
but those listed above may be considered for any given deployment but those listed above may be considered for any given deployment
architecture. architecture.
3.1. Centralized versus Distributed Deployment 3.1. Centralized versus Distributed Deployment
Centralized deployments of CGN (longer proximity to end user and/or Centralized deployments of CGN (longer proximity to end user and/or
higher densities of subscribers/connections to CGN instances) differ higher densities of subscribers/connections to CGN instances) differ
from distributed deployments of CGN (closer proximity to end user from distributed deployments of CGN (closer proximity to end user and
and/or lower densities of subscribers/connections to CGN instances). /or lower densities of subscribers/connections to CGN instances).
Service providers may likely deploy CGN translation points more Service providers may likely deploy CGN translation points more
centrally during initial phases if the early system demand is low. centrally during initial phases if the early system demand is low.
Early deployments may see light loading on these new systems since Early deployments may see light loading on these new systems since
legacy IPv4 services will continue to operate with most endpoints legacy IPv4 services will continue to operate with most endpoints
using globally unique IPv4 addresses. Exceptional cases which may using globally unique IPv4 addresses. Exceptional cases which may
drive heavy usage in initial stages may include operators who already drive heavy usage in initial stages may include operators who already
translate a significant portion of their IPv4 traffic; may transition translate a significant portion of their IPv4 traffic; may transition
to a CGN implementation from legacy translation mechanisms (i.e. to a CGN implementation from legacy translation mechanisms (i.e.
traditional firewalls); or build a green field deployment which may traditional firewalls); or build a green field deployment which may
see quick growth in the number of new IPv4 endpoints which require see quick growth in the number of new IPv4 endpoints which require
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Operators may also want to choose models that support transition to Operators may also want to choose models that support transition to
other translation environments such as DS-Lite [RFC6333] and/or NAT64 other translation environments such as DS-Lite [RFC6333] and/or NAT64
[RFC6146]. Operators will want to seek deployment models which are [RFC6146]. Operators will want to seek deployment models which are
conducive to meeting these goals as well. conducive to meeting these goals as well.
3.6. IPv4 Overlap Space 3.6. IPv4 Overlap Space
IPv4 address overlap for CGN translation realms may be required if IPv4 address overlap for CGN translation realms may be required if
insufficient IPv4 addresses are available within the operator insufficient IPv4 addresses are available within the operator
environment to assign internally unique IPv4 addresses to the CGN environment to assign internally unique IPv4 addresses to the CGN
subscriber base . The CGN deployment should provide mechanisms to subscriber base . The CGN deployment should provide mechanisms to
manage IPv4 overlap if required. manage IPv4 overlap if required.
3.7. Transactional Logging for CGN Systems 3.7. Transactional Logging for CGN Systems
CGNs may require transactional logging since the source IP and CGNs may require transactional logging since the source IP and
related transport protocol information is not easily visible to related transport protocol information is not easily visible to
external hosts and system. external hosts and system.
If needed, the CGN systems should be able to generate logs which If needed, the CGN systems should be able to generate logs which
identify internal realm host parameters (i.e. IP/Port) and identify internal realm host parameters (i.e. IP/Port) and associated
associated them to external realm parameters imposed by the them to external realm parameters imposed by the translator. The
translator. The logged information should be stored on the CGN logged information should be stored on the CGN hardware and/or
hardware and/or exported to another system for processing. The exported to another system for processing. The operator may choose
operator may choose to also enable mechanisms to help reduce logging to also enable mechanisms to help reduce logging such as block
such as block allocation of UDP and TCP ports or deterministic allocation of UDP and TCP ports or deterministic translation options
translation options such as [I-D.donley-behave-deterministic-cgn]. such as [I-D.donley-behave-deterministic-cgn].
Operators may need to keep track of this information (securely) to Operators may be legally obligated to keep track of translation
meet regulatory and/or legal obligations. Further information can be information. The operator may need to utilize their standard
found in [RFC6888] with respect to CGN logging requirements (Logging practices in handling sensitive customer data when storing and/or
Section). transporting such data. Further information can be found in
[RFC6888] with respect to CGN logging requirements (Logging section).
3.8. Base CGN Requirements 3.8. Base CGN Requirements
Whereas the requirements above represent assessed architectural Whereas the requirements above represent assessed architectural
requirements, the CGN platform will also need to meet the need to requirements, the CGN platform will also need to meet the need to
meet the base CGN requirements of a CGN function. Base requirements meet the base CGN requirements of a CGN function. Base requirements
include such functions as Bulk Port Allocation and other CGN device include such functions as Bulk Port Allocation and other CGN device
specific functions. These base CGN platform requirements are specific functions. These base CGN platform requirements are
captured within [RFC6888]. captured within [RFC6888].
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| Local | | Local |
| Content | | Content |
+-----------+ +-----------+
Figure 2: Internal Services and CGN By-Pass Figure 2: Internal Services and CGN By-Pass
An extension to the services delivery LSP is the ability to also An extension to the services delivery LSP is the ability to also
provide direct subscriber to subscriber traffic flows between CGN provide direct subscriber to subscriber traffic flows between CGN
zones. Each zone or realm may be fitted with separate CGN resources, zones. Each zone or realm may be fitted with separate CGN resources,
but the subtending subscribers don't necessarily need to be mediated but the subtending subscribers don't necessarily need to be mediated
(translated) by the CGN translators. This option, as shown in Figure (translated) by the CGN translators. This option, as shown in
3 below, is easy to implement and can only be enabled if no IPv4 Figure 3 below, is easy to implement and can only be enabled if no
address overlap is used between communicating CGN zones. IPv4 address overlap is used between communicating CGN zones.
Access Node-1 VRF Termination CGN-1 Access Node-1 VRF Termination CGN-1
+-------------+ +-----------+ +----------+ +-------------+ +-----------+ +----------+
| | | | | | | | | | | |
CPE-1 | +---------+ | | +-------+ | | +------+ | CPE-1 | +---------+ | | +-------+ | | +------+ |
+-----+ | | | | | | | | | | | | +-----+ | | | | | | | | | | | |
| --+--+-+- VRF --+-+-+ | | VRF | | | | | | | --+--+-+- VRF --+-+-+ | | VRF | | | | | |
+-----+ | | | | | | | | | | | | | +-----+ | | | | | | | | | | | | |
| +---------+ | | | +-------+ | | | | | | +---------+ | | | +-------+ | | | | |
| | | | | | |XLATE | | | | | | | | |XLATE | |
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are typically used by subscribes within an operator environment. A are typically used by subscribes within an operator environment. A
full review of the observed impacts related to CGN (NAT444) are full review of the observed impacts related to CGN (NAT444) are
covered in [RFC7021]. covered in [RFC7021].
6. IANA Considerations 6. IANA Considerations
This document has no IANA actions. This document has no IANA actions.
7. Security Considerations 7. Security Considerations
The same security considerations would typically exist for CGN An operator implementing CGN using BGP/MPLS IP VPNs should refer to
deployments when compared with traditional IPv4 based services. [RFC6888] section 7 for security considerations related to CGN
deployments. The operator should continue to employ standard
security methods in place for their standard MPLS deployment and can
also refer to the security considerations section in [RFC4364] which
discusses both control plane and data plane security.
8. BGP/MPLS IP VPN CGN Framework Discussion 8. BGP/MPLS IP VPN CGN Framework Discussion
The MPLS/VPN delivery method for a CGN deployment is an effective and The MPLS/VPN delivery method for a CGN deployment is an effective and
scalable way to deliver mass translation services. The architecture scalable way to deliver mass translation services. The architecture
avoids the complex requirements of traffic engineering and policy avoids the complex requirements of traffic engineering and policy
based routing when combining these new service flows to existing IPv4 based routing when combining these new service flows to existing IPv4
operation. This is advantageous since the NAT44/CGN environments operation. This is advantageous since the NAT44/CGN environments
should be introduced with as little impact as possible and these should be introduced with as little impact as possible and these
environments are expected to change over time. environments are expected to change over time.
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10.1. Normative References 10.1. Normative References
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006. Networks (VPNs)", RFC 4364, February 2006.
10.2. Informative References 10.2. Informative References
[I-D.donley-behave-deterministic-cgn] [I-D.donley-behave-deterministic-cgn]
Donley, C., Grundemann, C., Sarawat, V., Sundaresan, K., Donley, C., Grundemann, C., Sarawat, V., Sundaresan, K.,
and O. Vautrin, "Deterministic Address Mapping to Reduce and O. Vautrin, "Deterministic Address Mapping to Reduce
Logging in Carrier Grade NAT Deployments", Logging in Carrier Grade NAT Deployments", draft-donley-
draft-donley-behave-deterministic-cgn-06 (work in behave-deterministic-cgn-07 (work in progress), January
progress), July 2013. 2014.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets", E. Lear, "Address Allocation for Private Internets", BCP
BCP 5, RFC 1918, February 1996. 5, RFC 1918, February 1996.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, January 2001. Label Switching Architecture", RFC 3031, January 2001.
[RFC5332] Eckert, T., Rosen, E., Aggarwal, R., and Y. Rekhter, "MPLS [RFC5332] Eckert, T., Rosen, E., Aggarwal, R., and Y. Rekhter, "MPLS
Multicast Encapsulations", RFC 5332, August 2008. Multicast Encapsulations", RFC 5332, August 2008.
[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4 [RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification", Infrastructures (6rd) -- Protocol Specification", RFC
RFC 5969, August 2010. 5969, August 2010.
[RFC6037] Rosen, E., Cai, Y., and IJ. Wijnands, "Cisco Systems' [RFC6037] Rosen, E., Cai, Y., and IJ. Wijnands, "Cisco Systems'
Solution for Multicast in BGP/MPLS IP VPNs", RFC 6037, Solution for Multicast in BGP/MPLS IP VPNs", RFC 6037,
October 2010. October 2010.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6 NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, April 2011. Clients to IPv4 Servers", RFC 6146, April 2011.
[RFC6264] Jiang, S., Guo, D., and B. Carpenter, "An Incremental [RFC6264] Jiang, S., Guo, D., and B. Carpenter, "An Incremental
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