draft-ietf-lisp-interworking-03.txt   draft-ietf-lisp-interworking-04.txt 
Network Working Group D. Lewis Network Working Group D. Lewis
Internet-Draft D. Meyer Internet-Draft D. Meyer
Intended status: Experimental D. Farinacci Intended status: Experimental D. Farinacci
Expires: August 12, 2012 V. Fuller Expires: August 20, 2012 V. Fuller
Cisco Systems, Inc. Cisco Systems, Inc.
February 9, 2012 February 17, 2012
Interworking LISP with IPv4 and IPv6 Interworking LISP with IPv4 and IPv6
draft-ietf-lisp-interworking-03.txt draft-ietf-lisp-interworking-04.txt
Abstract Abstract
This document describes techniques for allowing sites running the This document describes techniques for allowing sites running the
Locator/ID Separation Protocol (LISP) to interoperate with Internet Locator/ID Separation Protocol (LISP) to interoperate with Internet
sites (which may be using either IPv4, IPv6, or both) but which are sites (which may be using either IPv4, IPv6, or both) but which are
not running LISP. A fundamental property of LISP speaking sites is not running LISP. A fundamental property of LISP speaking sites is
that they use Endpoint Identifiers (EIDs), rather than traditional IP that they use Endpoint Identifiers (EIDs), rather than traditional IP
addresses, in the source and destination fields of all traffic they addresses, in the source and destination fields of all traffic they
emit or receive. While EIDs are syntactically identical to IPv4 or emit or receive. While EIDs are syntactically identical to IPv4 or
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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 August 12, 2012. This Internet-Draft will expire on August 20, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 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
(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
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which use non-globally-routed EIDs, and non-LISP sites. The first is which use non-globally-routed EIDs, and non-LISP sites. The first is
the use of Proxy Ingress Tunnel router (PITRs), which originate the use of Proxy Ingress Tunnel router (PITRs), which originate
highly-aggregated routes to EID prefixes for non-LISP sites to use. highly-aggregated routes to EID prefixes for non-LISP sites to use.
It also describes the use of NAT by LISP ITRs when sending packets to It also describes the use of NAT by LISP ITRs when sending packets to
non-LISP hosts. Finally, it describes Proxy Egress Tunnel routers non-LISP hosts. Finally, it describes Proxy Egress Tunnel routers
(PETRs) LISP for sites relying on PITRs, and which are faced with (PETRs) LISP for sites relying on PITRs, and which are faced with
certain restrictions. certain restrictions.
A key behavior of the separation of Locators and End-Point-IDs is A key behavior of the separation of Locators and End-Point-IDs is
that EID prefixes are normally not advertised into the Internet's that EID prefixes are normally not advertised into the Internet's
Default Free Zone (DFZ). Specifically, only RLOCs are carried in the Default Free Zone (DFZ). Specifically, only Routing Locators (RLOCs)
Internet's DFZ. Existing Internet sites (and their hosts) which do are carried in the Internet's DFZ. Existing Internet sites (and
not run in the LISP protocol must still be able to reach sites their hosts) which do not run in the LISP protocol must still be able
numbered from LISP EID space. This draft describes three mechanisms to reach sites numbered from LISP EID space. This draft describes
that can be used to provide reachability between sites that are LISP- three mechanisms that can be used to provide reachability between
capable and those that are not. sites that are LISP-capable and those that are not.
The first mechanism uses a new network element, the LISP Proxy The first mechanism uses a new network element, the LISP Proxy
Ingress Tunnel Router (PITR) to act as a intermediate LISP Ingress Ingress Tunnel Router (PITR) to act as a intermediate LISP Ingress
Tunnel Router (ITR) for non-LISP-speaking hosts. The second Tunnel Router (ITR) for non-LISP-speaking hosts. The second
mechanism adds a form of Network Address Translation (NAT) mechanism adds a form of Network Address Translation (NAT)
functionality to Tunnel Routers (xTRs), to substitute routable IP functionality to Tunnel Routers (xTRs), to substitute routable IP
addresses for non-routable EIDs. The final network element is the addresses for non-routable EIDs. The final network element is the
LISP Proxy Egress Tunnel Routers (PETR), which act as an intermediate LISP Proxy Egress Tunnel Routers (PETR), which act as an intermediate
Egress Tunnel Router (ETR) for LISP sites which need to encapsulate Egress Tunnel Router (ETR) for LISP sites which need to encapsulate
packets LISP packets destined to non-LISP sites. packets LISP packets destined to non-LISP sites.
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reaches a router which cannot forward it (due to lack of a default reaches a router which cannot forward it (due to lack of a default
route), at which point the traffic is dropped. For traffic not to be route), at which point the traffic is dropped. For traffic not to be
dropped, either some mechanism to make this destination EID routable dropped, either some mechanism to make this destination EID routable
must be in place. Section 5 (PITRs) and Section 6 (LISP-NAT) must be in place. Section 5 (PITRs) and Section 6 (LISP-NAT)
describe two such mechanisms. describe two such mechanisms.
Case 4 also applies to packets returning to the LISP site, in Case 3. Case 4 also applies to packets returning to the LISP site, in Case 3.
3. Definition of Terms 3. Definition of Terms
Default Free Zone: The Default-Free Zone (DFZ) refers to the
collection of all Internet autonomous systems that do not require
a default route to route a packet to any destination.
LISP Routable (LISP-R) Site: A LISP site whose addresses are used as LISP Routable (LISP-R) Site: A LISP site whose addresses are used as
both globally routable IP addresses and LISP EIDs. both globally routable IP addresses and LISP EIDs.
LISP Non-Routable (LISP-NR) Site: A LISP site whose addresses are LISP Non-Routable (LISP-NR) Site: A LISP site whose addresses are
EIDs only, these EIDs are not found in the legacy Internet routing EIDs only, these EIDs are not found in the legacy Internet routing
table. table.
LISP Proxy Ingress Tunnel Router (PITR): PITRs are used to provide LISP Proxy Ingress Tunnel Router (PITR): PITRs are used to provide
interconnectivity between sites which use LISP EIDs and those interconnectivity between sites which use LISP EIDs and those
which do not. They act as gateways between those parts of the which do not. They act as gateways between those parts of the
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IGP. IGP.
5.4. Impact of the PITRs placement in the network 5.4. Impact of the PITRs placement in the network
There are several approaches that a network could take in placing There are several approaches that a network could take in placing
PITRs. Placing the PITR near the source of traffic allows for the PITRs. Placing the PITR near the source of traffic allows for the
communication between the non-LISP site and the LISP site to have the communication between the non-LISP site and the LISP site to have the
least "stretch" (i.e. the least number of forwarding hops when least "stretch" (i.e. the least number of forwarding hops when
compared to an optimal path between the sites). compared to an optimal path between the sites).
Some proposals, for example CRIO [CRIO], have suggested grouping Some proposals, for example Core Router-Integrated Overlay [CRIO],
PITRs near an arbitrary subset of ETRs and announcing a 'local' have suggested grouping PITRs near an arbitrary subset of ETRs and
subset of EID space. This model cannot guarantee minimum stretch if announcing a 'local' subset of EID space. This model cannot
the EID prefix route advertisement points are changed (such a change guarantee minimum stretch if the EID prefix route advertisement
might occur if a site adds, removes, or replaces one or more of its points are changed (such a change might occur if a site adds,
ISP connections). removes, or replaces one or more of its ISP connections).
5.5. Benefit to Networks Deploying PITRs 5.5. Benefit to Networks Deploying PITRs
When packets destined for LISP-NR sites arrive and are encapsulated When packets destined for LISP-NR sites arrive and are encapsulated
at a Proxy-ITR, a new LISP packet header is pre-pended. This causes at a Proxy-ITR, a new LISP packet header is pre-pended. This causes
the packet's destination to be set to the destination ETRs RLOC. the packet's destination to be set to the destination ETRs RLOC.
Because packets are thus routed towards RLOCs, it can potentially Because packets are thus routed towards RLOCs, it can potentially
better follow the Proxy-ITR network's traffic engineering policies better follow the Proxy-ITR network's traffic engineering policies
(such as closest exit routing). This also means that providers which (such as closest exit routing). This also means that providers which
are not default-free and do not deploy Proxy-ITRs end up sending more are not default-free and do not deploy Proxy-ITRs end up sending more
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packets will be able to natively reach the site. packets will be able to natively reach the site.
6.1. Using LISP-NAT with LISP-NR EIDs 6.1. Using LISP-NAT with LISP-NR EIDs
LISP-NAT allows a host with a LISP-NR EID to send packets to non-LISP LISP-NAT allows a host with a LISP-NR EID to send packets to non-LISP
hosts by translating the LISP-NR EID to a globally unique address (a hosts by translating the LISP-NR EID to a globally unique address (a
LISP-R EID). This globally unique address may be a either a PI or PA LISP-R EID). This globally unique address may be a either a PI or PA
address. address.
An example of this translation follows. For this example, a site has An example of this translation follows. For this example, a site has
been assigned a LISP-NR EID of 220.1.1.0/24. In order to utilize been assigned a LISP-NR EID of 203.0.113.0/24. In order to utilize
LISP-NAT, the site has also been provided the PA EID of LISP-NAT, the site has also been provided the PA EID of 192.0.2.0/24,
128.200.1.0/24, and uses the first address (128.200.1.1) as the and uses the first address (192.0.2.1) as the site's RLOC. The rest
site's RLOC. The rest of this PA space (128.200.1.2 to of this PA space (192.0.2.2 to 192.0.2.254) is used as a translation
128.200.1.254) is used as a translation pool for this site's hosts pool for this site's hosts who need to send packets to non-LISP
who need to send packets to non-LISP hosts. hosts.
The translation table might look like the following: The translation table might look like the following:
Site NR-EID Site R-EID Site's RLOC Translation Pool Site NR-EID Site R-EID Site's RLOC Translation Pool
============================================================== ==============================================================
220.1.1.0/24 128.200.1.0/24 128.200.1.1 128.200.1.2-254 203.0.113.0/24 192.0.2.0/24 192.0.2.1 192.0.2.2-254
Figure 1: Example Translation Table Figure 1: Example Translation Table
The Host 220.1.1.2 sends a packet (which, for the purposes of this The Host 203.0.113.2 sends a packet (which, for the purposes of this
example is destined for a non-LISP site) to its default route (the example is destined for a non-LISP site) to its default route (the
ITR). The ITR receives the packet, and determines that the ITR). The ITR receives the packet, and determines that the
destination is not a LISP site. How the ITR makes this determination destination is not a LISP site. How the ITR makes this determination
is up to the ITRs implementation of the EID-to-RLOC mapping system is up to the ITRs implementation of the EID-to-RLOC mapping system
used (see, for example [LISP-ALT]). used (see, for example [LISP-ALT]).
The ITR then rewrites the source address of the packet from 220.1.1.2 The ITR then rewrites the source address of the packet from
to 128.200.1.2, which is the first available address in the LISP-R 203.0.113.2 to 192.0.2.2, which is the first available address in the
EID space available to it. The ITR keeps this translation in a table LISP-R EID space available to it. The ITR keeps this translation in
in order to reverse this process when receiving packets destined to a table in order to reverse this process when receiving packets
128.200.1.2. destined to 192.0.2.2.
Finally, when the ITR forwards this packet without encapsulating it, Finally, when the ITR forwards this packet without encapsulating it,
it uses the entry in its LISP-NAT table to translate the returning it uses the entry in its LISP-NAT table to translate the returning
packets' destination IPs to the proper host. packets' destination IPs to the proper host.
6.2. LISP Sites with Hosts using RFC 1918 Addresses Sending to non-LISP 6.2. LISP Sites with Hosts using RFC 1918 Addresses Sending to non-LISP
Sites Sites
In the case where hosts using RFC 1918 addresses desire to send In the case where hosts using RFC 1918 addresses desire to send
packets to non-LISP hosts, the LISP-NAT implementation acts much like packets to non-LISP hosts, the LISP-NAT implementation acts much like
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Thanks goes to Christian Vogt, Lixia Zhang, Robin Whittle, Michael Thanks goes to Christian Vogt, Lixia Zhang, Robin Whittle, Michael
Menth, and Xuewei Wang, and Noel Chiappa who have made insightful Menth, and Xuewei Wang, and Noel Chiappa who have made insightful
comments with respect to LISP Interworking and transition mechanisms. comments with respect to LISP Interworking and transition mechanisms.
A special thanks goes to Scott Brim for his initial brainstorming of A special thanks goes to Scott Brim for his initial brainstorming of
these ideas and also for his careful review. these ideas and also for his careful review.
11. IANA Considerations 11. IANA Considerations
This document creates no new requirements on IANA namespaces This document creates no new requirements on IANA namespaces
[RFC2434]. [RFC5226].
12. References 12. References
12.1. Normative References 12.1. Normative References
[LISP] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, [LISP] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol (LISP)", "Locator/ID Separation Protocol (LISP)",
draft-ietf-lisp-20 (work in progress), January 2012. draft-ietf-lisp-20 (work in progress), January 2012.
[LISP-ALT] [LISP-ALT]
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Scaling IP Routing with the Core Router-Integrated Scaling IP Routing with the Core Router-Integrated
Overlay", January 2006. Overlay", January 2006.
[LISP-DEPLOY] [LISP-DEPLOY]
Jakab, L., Cabellos-Aparicio, A., Coras, F., Domingo- Jakab, L., Cabellos-Aparicio, A., Coras, F., Domingo-
Pascual, J., and D. Lewis, "LISP Network Element Pascual, J., and D. Lewis, "LISP Network Element
Deployment Considerations", Deployment Considerations",
draft-ietf-lisp-deployment-02.txt (work in progress), draft-ietf-lisp-deployment-02.txt (work in progress),
November 2011. November 2011.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC2993] Hain, T., "Architectural Implications of NAT", RFC 2993, [RFC2993] Hain, T., "Architectural Implications of NAT", RFC 2993,
November 2000. November 2000.
[RFC4787] Audet, F. and C. Jennings, "Network Address Translation [RFC4787] Audet, F. and C. Jennings, "Network Address Translation
(NAT) Behavioral Requirements for Unicast UDP", BCP 127, (NAT) Behavioral Requirements for Unicast UDP", BCP 127,
RFC 4787, January 2007. RFC 4787, January 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5382] Guha, S., Biswas, K., Ford, B., Sivakumar, S., and P. [RFC5382] Guha, S., Biswas, K., Ford, B., Sivakumar, S., and P.
Srisuresh, "NAT Behavioral Requirements for TCP", BCP 142, Srisuresh, "NAT Behavioral Requirements for TCP", BCP 142,
RFC 5382, October 2008. RFC 5382, October 2008.
Authors' Addresses Authors' Addresses
Darrel Lewis Darrel Lewis
Cisco Systems, Inc. Cisco Systems, Inc.
Email: darlewis@cisco.com Email: darlewis@cisco.com
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