Network Working Group L. Iannone
Internet-Draft Telekom Innovation Laboratories
Intended status: Informational D. Lewis
Expires: May 3, 2012 D. Meyer
V. Fuller
Cisco Systems, Inc.
October 31, 2011
LISP EID Block
draft-ietf-lisp-eid-block-01.txt
Abstract
This is a direction to IANA to allocate a /16 IPv6 prefix for use
with the Locator/ID Separation Protocol (LISP). The prefix will be
used by sites deploying LISP as EID (Endpoint IDentifier) addressing
space for local intra-domain routing and global endpoint
identification.
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 May 3, 2012.
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Table of Contents
1. Requirements Notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 3
4. Rationale and Intent . . . . . . . . . . . . . . . . . . . . . 5
5. Expected use . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Block Dimension . . . . . . . . . . . . . . . . . . . . . . . 6
7. Action Plan . . . . . . . . . . . . . . . . . . . . . . . . . 7
8. Routing Considerations . . . . . . . . . . . . . . . . . . . . 7
9. Security Considerations . . . . . . . . . . . . . . . . . . . 8
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
12.1. Normative References . . . . . . . . . . . . . . . . . . 8
12.2. Informative References . . . . . . . . . . . . . . . . . 9
Appendix A. Document Change Log . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Requirements Notation
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 [RFC2119].
2. Introduction
This document directs the IANA to allocate a /16 IPv6 prefix for use
with the Locator/ID Separation Protocol (LISP - [I-D.ietf-lisp]),
LISP Map Server ([I-D.ietf-lisp-ms]), LISP Alternative Topology
(LISP+ALT - [I-D.ietf-lisp-alt]) (or other) mapping system, and LISP
Interworking ([I-D.ietf-lisp-interworking]).
This block will be used as global Endpoint IDentifier (EID) space
(Section 3).
3. Definition of Terms
LISP operates on two name spaces and introduces several new network
elements. This section provides high-level definitions of the LISP
name spaces and network elements and as such, it MUST NOT be
considered as an authoritative source. The reference to the
authoritative document for each term is included in every term
description.
Legacy Internet: The portion of the Internet which does not run LISP
and does not participate in LISP+ALT or any other mapping system.
LISP site: A LISP site is a set of routers in an edge network that
are under a single technical administration. LISP routers that
reside in the edge network are the demarcation points to separate
the edge network from the core network. See [I-D.ietf-lisp] for
more details.
Endpoint ID (EID): An EID is a 32-bit (for IPv4) or 128-bit (for
IPv6) value used in the source and destination address fields of
the first (most inner) LISP header of a packet. A packet that is
emitted by a system contains EIDs in its headers and LISP headers
are prepended only when the packet reaches an Ingress Tunnel
Router (ITR) on the data path to the destination EID. The source
EID is obtained via existing mechanisms used to set a host's
"local" IP address. An EID is allocated to a host from an EID-
prefix block associated with the site where the host is located.
See [I-D.ietf-lisp] for more details.
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EID-prefix: A power-of-two block of EIDs that are allocated to a
site by an address allocation authority. See [I-D.ietf-lisp] for
more details.
EID-Prefix Aggregate: A set of EID-prefixes said to be aggregatable
in the [RFC4632] sense. That is, an EID-Prefix aggregate is
defined to be a single contiguous power-of-two EID-prefix block.
Such a block is characterized by a prefix and a length. See
[I-D.ietf-lisp] for more details.
Routing LOCator (RLOC): A RLOC is an IPv4 or IPv6 address of an
egress tunnel router (ETR). A RLOC is the output of an EID-to-
RLOC mapping lookup. An EID maps to one or more RLOCs.
Typically, RLOCs are numbered from topologically aggregatable
blocks that are assigned to a site at each point to which it
attaches to the global Internet; where the topology is defined by
the connectivity of provider networks, RLOCs can be thought of as
Provider Aggregatable (PA) addresses. See [I-D.ietf-lisp] for
more details.
EID-to-RLOC Mapping: A binding between an EID-Prefix and the RLOC-
set that can be used to reach the EID-Prefix. The general term
"mapping" always refers to an EID-to-RLOC mapping. See
[I-D.ietf-lisp] for more details.
Ingress Tunnel Router (ITR): An Ingress Tunnel Router (ITR) is a
router that accepts receives IP packets from site end-systems on
one side and sends LISP-encapsulated IP packets toward the
Internet on the other side. The router treats the "inner" IP
destination address as an EID and performs an EID-to-RLOC mapping
lookup. The router then prepends an "outer" IP header with one of
its globally-routable RLOCs in the source address field and the
result of the mapping lookup in the destination address field.
See [I-D.ietf-lisp] for more details.
Egress Tunnel Router (ETR): An Egress Tunnel Router (ETR) receives
LISP-encapsulated IP packets from the Internet on one side and
sends decapsulated IP packets to site end-systems on the other
side. An ETR router accepts an IP packet where the destination
address in the "outer" IP header is one of its own RLOCs. The
router strips the "outer" header and forwards the packet based on
the next IP header found. See [I-D.ietf-lisp] for more details.
Proxy ITR (PITR): A Proxy-ITR (PITR) acts like an ITR but does so on
behalf of non-LISP sites which send packets to destinations at
LISP sites. See [I-D.ietf-lisp-interworking] for more details.
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Proxy ETR (PETR): A Proxy-ETR (PETR) acts like an ETR but does so on
behalf of LISP sites which send packets to destinations at non-
LISP sites. See [I-D.ietf-lisp-interworking] for more details.
Map Server (MS): A network infrastructure component that learns EID-
to-RLOC mapping entries from an authoritative source (typically an
ETR). A Map-Server publishes these mappings in the distributed
mapping system. See [I-D.ietf-lisp-ms] for more details.
Map Resolver (MR): A network infrastructure component that accepts
LISP Encapsulated Map-Requests, typically from an ITR, quickly
determines whether or not the destination IP address is part of
the EID namespace; if it is not, a Negative Map-Reply is
immediately returned. Otherwise, the Map-Resolver finds the
appropriate EID-to-RLOC mapping by consulting the distributed
mapping database system. See [I-D.ietf-lisp-ms] for more details.
The LISP Alternative Logical Topology (ALT): The virtual overlay
network made up of tunnels between LISP+ALT Routers. The Border
Gateway Protocol (BGP) runs between ALT Routers and is used to
carry reachability information for EID-prefixes. The ALT provides
a way to forward Map-Requests toward the ETR that "owns" an EID-
prefix. See [I-D.ietf-lisp-alt] for more details.
ALT Router: The device on which runs the ALT. The ALT is a static
network built using tunnels between ALT Routers. These routers
are deployed in a roughly-hierarchical mesh in which routers at
each level in the topology are responsible for aggregating EID-
Prefixes learned from those logically "below" them and advertising
summary prefixes to those logically "above" them. Prefix learning
and propagation between ALT Routers is done using BGP. When an
ALT Router receives an ALT Datagram, it looks up the destination
EID in its forwarding table (composed of EID-Prefix routes it
learned from neighboring ALT Routers) and forwards it to the
logical next-hop on the overlay network. The primary function of
LISP+ALT routers is to provide a lightweight forwarding
infrastructure for LISP control-plane messages (Map-Request and
Map-Reply), and to transport data packets when the packet has the
same destination address in both the inner (encapsulating)
destination and outer destination addresses ((i.e., a Data Probe
packet). See [I-D.ietf-lisp-alt] for more details.
4. Rationale and Intent
With the current specifications, if an ITR is sending to all types of
destinations (i.e., non-LISP destinations, LISP destinations not in
the IPv6 EID Block, and LISP destinations in the IPv6 EID Block) the
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only way to understand whether or not to encapsulate the traffic is
to perform a cache lookup and, in case of cache-miss, send a Map-
Request to the mapping system. In the meanwhile, packets can be
dropped.
By defining an IPv6 EID Block is possible to configure the router so
to natively forward all packets that have not a destination address
in the block, without performing any lookup whatsoever. This will
give a tighter control over the traffic in the initial experimental
phase, while facilitating its large-scale deployment.
The EID Block will be used only at configuration level, it is
RECOMMENDED not to hard-code in any way the IPv6 EID Block in the
router hardware. This allows to avoid locking out sites that may
want to switch to LISP while keeping their own IPv6 prefix, which is
not in the IPv6 EID Block.
5. Expected use
Sites planning to deploy LISP may request a prefix in the IPv6 EID
Block. Such prefix will be used for routing and endpoint
identification inside the site requesting it. Mappings related to
such prefix, or part of it, will be made available through the
mapping system in use or registered to one or more Map-Server(s).
Too guarantee reachability from the Legacy Internet the prefix could
be announced in the BGP routing infrastructure by one or more
PITR(s), possibly as part of a larger prefix, aggregating several
prefixes of several sites.
6. Block Dimension
The working group reached consensus on an initial allocation of a /16
prefix out of a /12 block which is asked to remain reserved for
future use as EID b space. The reason of such consensus is manifold:
o A /16 prefix is suffiently large to cover initial allocation and
requests for prefoxes in the EID space in the next few years for
very large scale experimentation and deployment. As a comparison
is worth to mention that the current LISP Beta Network ([BETA]) is
using a /32 prefix, hence a /16 should be sufficiently large to
accomodate growth in the near future.
o The request to reserve the /12 prefix covering the initial /16
allocation is in line with IANA policies that fix to /12 the
minimum IPv6 allocation.
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o The proposed alignment provides as well a natural support for DNS.
In particular, reverse DNS for IPv6 in the special ip6.arpa domain
is represented as sequence of nibbles. A different alignment
would force to a binary representation.
7. Action Plan
This document requests IANA to initially allocate a /16 prefix out of
the IPv6 addressing space for use as EID in LISP (Locator/ID
Separation protocol). It is suggested to IANA to temporarily avoid
allocating any other address block the same /12 prefix the EID /16
prefix belongs to. This is to accommodate future requests of EID
space without fragmenting the EID addressing space. This will also
help from an operational point of view, since it will be sufficient
to change the subnet mask length in existing deployments.
If in the future there will be need for a larger EID Block the
address space adjacent the EID Block could be allocate by IANA
according to the current policies.
8. Routing Considerations
In order to provide connectivity between the Legacy Internet and LISP
sites, PITRs announcing large aggregates of the IPv6 EID Block could
be deployed. By doing so, PITRs will attract traffic destined to
LISP sites in order to encapsulate and forward it toward the specific
destination LISP site. Routers in the Legacy Internet MUST treat
announcements of prefixes from the IPv6 EID Block as normal
announcements, applying best current practice for traffic engineering
and security.
Even in a LISP site, not all routers need to run LISP elements. In
particular, routers that are not at the border of the local domain,
used only for intra-domain routing, do not need to provide any
specific LISP functionality but MUST be able to route traffic using
addresses in the IPv6 EID Block.
For the above-mentioned reasons, routers that do not run any LISP
element, MUST NOT include any special handling code or hardware for
addresses in the IPv6 EID Block. In particular, it is RECOMMENDED
that the default router configuration does not handle such addresses
in any special way. Doing differently could prevent communication
between the Legacy Internet and LISP sites or even break local intra-
domain connectivity.
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9. Security Considerations
This document does not introduce new security threats in the LISP
architecture nor in the Legacy Internet architecture.
10. Acknowledgments
Special thanks to Roque Gagliano for his suggestions and pointers to
the IANA allocation policies. Thanks to Marla Azinger, Chris Morrow,
and Peter Schoenmaker, all made insightful comments on early versions
of this draft.
11. IANA Considerations
This document instructs the IANA to assign a /16 IPv6 prefix for use
as the global LISP EID space using an hierarchical allocation as
outlined in [RFC2434]. During the discussion related to this
document, the LISP Working Group agreed in suggesting to IANA to
reserve adjacent addressing space for future use as EID space if
needs come. Following the policies outlined in [RFC2434], such space
will be assigned only upon IETF Consensus. This document does not
specify any specific value for the requested address block.
12. References
12.1. Normative References
[I-D.ietf-lisp]
Farinacci, D., Fuller, V., Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol (LISP)",
draft-ietf-lisp-15 (work in progress), July 2011.
[I-D.ietf-lisp-alt]
Fuller, V., Farinacci, D., Meyer, D., and D. Lewis, "LISP
Alternative Topology (LISP+ALT)", draft-ietf-lisp-alt-06
(work in progress), March 2011.
[I-D.ietf-lisp-interworking]
Lewis, D., Meyer, D., Farinacci, D., and V. Fuller,
"Interworking LISP with IPv4 and IPv6",
draft-ietf-lisp-interworking-02 (work in progress),
June 2011.
[I-D.ietf-lisp-ms]
Fuller, V. and D. Farinacci, "LISP Map Server Interface",
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draft-ietf-lisp-ms-12 (work in progress), October 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing
(CIDR): The Internet Address Assignment and Aggregation
Plan", BCP 122, RFC 4632, August 2006.
12.2. Informative References
[BETA] LISP Beta Network, "http://www.lisp4.net", 2008-2011.
Appendix A. Document Change Log
Version 01 Posted October 2011.
o Added Section 6.
Version 00 Posted July 2011.
o Updated section "IANA Considerations"
o Added section "Rationale and Intent" explaining why the EID block
allocation is useful.
o Added section "Expected Use" explaining how sites can request and
use a prefix in the IPv6 EID Block.
o Added section "Action Plan" suggesting IANA to avoid allocating
address space adjacent the allocated EID block in order to
accommodate future EID space requests.
o Added section "Routing Consideration" describing how routers not
running LISP deal with the requested address block.
o Added the present section to keep track of changes.
o Rename of draft-meyer-lisp-eid-block-02.txt.
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Authors' Addresses
Luigi Iannone
Telekom Innovation Laboratories
Email: luigi@net.t-labs.tu-berlin.de
Darrel Lewis
Cisco Systems, Inc.
Email: darlewis@cisco.com
David Meyer
Cisco Systems, Inc.
Email: dmm@cisco.com
Vince Fuller
Cisco Systems, Inc.
Email: vaf@cisco.com
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