Internet DRAFT - draft-ietf-lisp-lig
draft-ietf-lisp-lig
Network Working Group D. Farinacci
Internet-Draft D. Meyer
Intended status: Experimental cisco Systems
Expires: March 12, 2012 September 9, 2011
LISP Internet Groper (LIG)
draft-ietf-lisp-lig-06
Abstract
A simple tool called the LISP Internet Groper or 'lig' can be used to
query the LISP mapping database. This draft describes how it works.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 4
3. Basic Overview . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Implementation Details . . . . . . . . . . . . . . . . . . . . 9
4.1. LISP Router Implementation . . . . . . . . . . . . . . . . 9
4.2. Public Domain Host Implementation . . . . . . . . . . . . 10
5. Testing the ALT . . . . . . . . . . . . . . . . . . . . . . . 12
6. Future Enhancements . . . . . . . . . . . . . . . . . . . . . 13
7. Deployed Network Diagnostic Tools . . . . . . . . . . . . . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 15
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
10.1. Normative References . . . . . . . . . . . . . . . . . . . 17
10.2. Informative References . . . . . . . . . . . . . . . . . . 17
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
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1. Introduction
LISP [LISP] specifies an architecture and mechanism for replacing the
addresses currently used by IP with two separate name spaces:
Endpoint IDs (EIDs), used within sites, and Routing Locators (RLOCs),
used on the transit networks that make up the Internet
infrastructure. To achieve this separation, the Locator/ID
Separation Protocol (LISP) defines protocol mechanisms for mapping
from EIDs to RLOCs. In addition, LISP assumes the existence of a
database to store and propagate those mappings globally. Several
such databases have been proposed, among them: LISP-CONS [CONS],
LISP-NERD [NERD], and LISP+ALT [ALT], with LISP+ALT being the system
that is currently being implemented and deployed on the pilot LISP
network.
In conjunction with the various mapping systems, there exists a
network based API called LISP Map-Server [LISP-MS]. Using Map-
Resolvers and Map-Servers allows LISP sites to query and register
into the database in a uniform way independent of the mapping system
used. Sending Map-Requests to Map-Resolvers provides a secure
mechanism to obtain a Map-Reply containing the authoritative EID-to-
RLOC mapping for a destination LISP site.
The 'lig' is a manual management tool to query the mapping database.
It can be run by all devices which implement LISP, including ITRs,
ETRs, PITRs, PETRs, Map-Resolvers, Map-Servers, and LISP-ALT routers,
as well as by a host system at either a LISP-capable or non-LISP-
capable site.
The mapping database system is typically a public database used for
wide-range connectivity across Internet sites. The information in
the public database is purposely not kept private so it can be
generally accessible for public use.
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2. Definition of Terms
Map-Server: a network infrastructure component which learns EID-to-
RLOC mapping entries from an authoritative source (typically, an
ETR, though static configuration or another out-of-band mechanism
may be used). A Map-Server advertises these mappings in the
distributed mapping database.
Map-Resolver: a network infrastructure component which 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.
Routing Locator (RLOC): the IPv4 or IPv6 address of an egress
tunnel router (ETR). It is the output of a 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. Thus, the topology is defined by the connectivity of
provider networks and RLOCs can be thought of as PA addresses.
Multiple RLOCs can be assigned to the same ETR device or to
multiple ETR devices at a site.
Endpoint ID (EID): 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. The host obtains a
destination EID the same way it obtains a destination address
today, for example through a DNS lookup. 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. An EID can be
used by a host to refer to other hosts. EIDs must not be used as
LISP RLOCs. Note that EID blocks may be assigned in a
hierarchical manner, independent of the network topology, to
facilitate scaling of the mapping database. In addition, an EID
block assigned to a site may have site-local structure
(subnetting) for routing within the site; this structure is not
visible to the global routing system.
EID-to-RLOC Cache: a short-lived, on-demand table in an ITR that
stores, tracks, and is responsible for timing-out and otherwise
validating EID-to-RLOC mappings. This cache is distinct from the
full "database" of EID-to-RLOC mappings, it is dynamic, local to
the ITR(s), and relatively small while the database is
distributed, relatively static, and much more global in scope.
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EID-to-RLOC Database: a global distributed database that contains
all known EID-prefix to RLOC mappings. Each potential ETR
typically contains a small piece of the database: the EID-to-RLOC
mappings for the EID prefixes "behind" the router. These map to
one of the router's own, globally-visible, IP addresses.
Encapsulated Map-Request (EMR): an EMR is a Map-Request message
which is encapsulated with another LISP header using UDP
destination port number 4341. It is used so an ITR, PITR, or a
system initiating a 'lig' command can get the Map-Request to a
Map-Resolver by using locater addresses. When the Map-Request is
decapsulated by the Map-Resolver it will be forwarded on the ALT
network to the Map-Server that has injected the EID-prefix for a
registered site. The Map-Server will then encapsulate the Map-
Request in a LISP packet and send it to an an ETR at the site.
The ETR will then return an authoritative reply to the system that
initiated the request. See [LISP] for packet format details.
Ingress Tunnel Router (ITR): An ITR is a router which accepts an IP
packet with a single IP header (more precisely, an IP packet that
does not contain a LISP header). The router treats this "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. Note that this destination RLOC may be an
intermediate, proxy device that has better knowledge of the EID-
to-RLOC mapping closer to the destination EID. In general, an ITR
receives IP packets from site end-systems on one side and sends
LISP-encapsulated IP packets toward the Internet on the other
side.
Egress Tunnel Router (ETR): An ETR is a router that 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. In
general, an 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. ETR functionality does not have to
be limited to a router device. A server host can be the endpoint
of a LISP tunnel as well.
Proxy ITR (PITR): A PITR is also known as a PTR is defined and
described in [INTERWORK], a PITR acts like an ITR but does so on
behalf of non-LISP sites which send packets to destinations at
LISP sites.
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Proxy ETR (PETR): A PETR is defined and described in [INTERWORK], a
PETR acts like an ETR but does so on behalf of LISP sites which
send packets to destinations at non-LISP sites.
xTR: A xTR is a reference to an ITR or ETR when direction of data
flow is not part of the context description. xTR refers to the
router that is the tunnel endpoint. Used synonymously with the
term "Tunnel Router". For example, "An xTR can be located at the
Customer Edge (CE) router", meaning both ITR and ETR functionality
is at the CE router.
Provider Assigned (PA) Addresses: PA addresses are an address block
assigned to a site by each service provider to which a site
connects. Typically, each block is sub-block of a service
provider Classless Inter-Domain Routing (CIDR) [RFC4632] block and
is aggregated into the larger block before being advertised into
the global Internet. Traditionally, IP multihoming has been
implemented by each multi-homed site acquiring its own, globally-
visible prefix. LISP uses only topologically-assigned and
aggregatable address blocks for RLOCs, eliminating this
demonstrably non-scalable practice.
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3. Basic Overview
When the lig command is run, a Map-Request is sent for a destination
EID. When a Map-Reply is returned, the contents are displayed to the
user. The information displayed includes:
o The EID-prefix for the site the queried destination EID matches.
o The locator address of the Map Replier.
o The locator-set for the mapping entry which includes the locator
address, up/down status, priority, and weight of each locator.
o An round-trip-time estimate for the Map-Request/Map-Reply
exchange.
A possible syntax for a lig command could be:
lig <destination> [source <source>] [to <map-resolver>]
Parameter description:
<destination>: is either a Fully Qualified Domain Name or a
destination EID for a remote LISP site.
source <source>: is an optional source EID to be inserted in the
"Source EID" field of the Map-Request.
to <map-resolver>: is an optional Fully Qualified Domain Name or
RLOC address for a Map-Resolver.
The lig utility has two use cases. The first being a way to query
the mapping database for a particular EID. And the other to verify
if a site has registered successfully with a Map-Server.
The first usage has already been described. Verifying registration
is called "ligging yourself". What occurs is in the lig initiator, a
Map-Request is sent for one of the EIDs for the lig initiator's site.
The Map-Request is then returned to one of the ETRs for the lig
initiating site. In response to the Map-Request, a Map-Reply is sent
back to the locator address of the lig initiator (note the Map-Reply
could be sent by the lig initiator). That Map-Reply is processed and
the mapping data for the lig initiating site is displayed for the
user. Refer to the syntax in section Section 4.1 for an
implementation of "ligging yourself". However, for host-based
implementations within a LISP site, "lig self" is less useful since
the host may not have an RLOC to receive a Map-Reply with. But, lig
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can be used in a non-LISP site as well as from infrastructure hosts
to get mapping information.
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4. Implementation Details
4.1. LISP Router Implementation
The cisco LISP prototype implementation has support for lig for IPv4
and IPv6. The command line description is:
lig <dest-eid> [source <source-eid>] [to <mr>] [count <1-5>]
This command initiates the LISP Internet Groper. It is similar to
the DNS analogue 'dig' but works on the LISP mapping database. When
this command is invoked, the local system will send a Map-Request to
the configured Map-Resolver. When a Map-Reply is returned, its
contents will be displayed to the user. By default, up to 3 Map-
Requests are sent if no Map-Reply is returned but once a Map-Reply is
returned no other Map-Requests are sent. The destination can take a
DNS name, or an IPv4 or IPv6 EID address. The <source-eid> can be
one of the EID addresses assigned to the site in the default VRF.
When <mr> is specified, then the Map-Request is sent to the address.
Otherwise, the Map-Request is sent to a configured Map-Resolver.
When a Map-Resolver is not configured then the Map-Request is sent on
the ALT network if the local router is attached to the ALT. When
"count <1-5>" is specified, 1, 2, 3, 4, or 5 Map-Requests are sent.
Some sample output:
router# lig abc.example.com
Send map-request to 10.0.0.1 for 192.168.1.1 ...
Received map-reply from 10.0.0.2 with rtt 0.081468 secs
Map-cache entry for abc.example.com EID 192.168.1.1:
192.168.1.0/24, uptime: 13:59:59, expires: 23:59:58,
via map-reply, auth
Locator Uptime State Priority/Weight Packets In/Out
10.0.0.2 13:59:59 up 1/100 0/14
Using lig to "lig yourself" is accomplished with the following
syntax:
lig {self | self6} [source <source-eid>] [to <mr>] [count <1-5>]
Use this command for a simple way to see if the site is registered
with the mapping database system. The destination-EID address for
the Map-Request will be the first configured EID-prefix for the site
(with the host-bits set to 0). For example, if the site's EID-prefix
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is 192.168.1.0/24, the destination-EID for the Map-Request is
192.168.1.0. The source-EID address for the Map-Request will also be
192.168.1.0 (in this example) and the Map-Request is sent to the
configured Map-Resolver. If the Map-Resolver and Map-Server are the
same LISP system, then the "lig self" is testing if the Map-Resolver
can "turn back a Map-Request to the site". If another Map-Resolver
is used, it can test that the site's EID-prefix has been injected
into the ALT infrastructure in which case the lig Map-Request is
processed by the Map-Resolver, propagated through each ALT router hop
to the site's registered Map-Server. Then the Map-Server returns the
Map-Request to the originating site. In which case, an xTR at the
originating site sends a Map-Reply to the source of the Map-Request
(could be itself or another xTR for the site). All other command
parameters are described above. Using "lig self6" tests for
registering of IPv6 EID- prefixes.
Some sample output for ligging yourself:
router# lig self
Send loopback map-request to 10.0.0.1 for 192.168.2.0 ...
Received map-reply from 10.0.0.3 with rtt 0.001592 secs
Map-cache entry for EID 192.168.2.0:
192.168.2.0/24, uptime: 00:00:02, expires: 23:59:57
via map-reply, self
Locator Uptime State Priority/Weight Packets In/Out
10.0.0.3 00:00:02 up 1/100 0/0
router# lig self6
Send loopback map-request to 10.0.0.1 for 2001:db8:1:: ...
Received map-reply from 10::1 with rtt 0.044372 secs
Map-cache entry for EID 192:168:1:::
2001:db8:1::/48, uptime: 00:00:01, expires: 23:59:58
via map-reply, self
Locator Uptime State Priority/Weight Packets In/Out
10.0.0.3 00:00:01 up 1/100 0/0
2001:db8:ffff::1 00:00:01 up 2/0 0/0
4.2. Public Domain Host Implementation
There is a public domain implementation that can run on any x86 based
system. The only requirement is that the system that initiates lig
must have an address assigned from the locator namespace.
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lig [-d] <eid> -m <map-resolver> [-c <count>] [-t <timeout>]
Parameter description:
-d: prints additional protocol debug output.
<eid>: is the destination EID or FQDN of a LISP host.
-m <map-resolver>: is the RLOC address or FQDN of a Map-Resolver.
-c <count>: the number of Map-Requests to send before the first Map-
Reply is returned. The default value is 3. The range is from 1
to 5.
-t <timeout>: the amount of time, in seconds, before another Map-
Request is sent when no Map-Reply is returned. The default value
is 2 seconds. The range is from 1 to 5.
Some sample output:
% lig xyz.example.com -m 10.0.0.1
Send map-request to 10.0.0.1 for 192.168.1.1 ...
Received map-reply from 10.0.0.2 with rtt 0.04000 sec
Mapping entry for EID 192.168.1.1:
192.168.1.0/24, record ttl: 60
Locator State Priority/Weight
10.0.0.1 up 1/25
10.0.0.2 up 1/25
10.0.0.3 up 1/25
10.0.0.4 up 2/25
The public domain implementation of lig is available at
http://github.com/davidmeyer/lig.
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5. Testing the ALT
There are cases where a Map-Reply is returned from a lig request but
the user doesn't really know how much of the mapping infrastructure
was tested. There are two cases to consider, avoiding the ALT and
traversing the ALT.
When an ITR sends a lig request to its Map-Resolver for a
destination-EID, the Map-Resolver could also be configured as a Map-
Server. And if the destination-EID is for a site that registers with
this Map-Server, the Map-Request is sent to the site directly without
testing the ALT. This occurs because the Map-Server is the source of
the advertisement for the site's EID-prefix. So if the map-reply is
returned to the lig requesting site, you cannot be sure that other
sites can reach the same destination-EID.
If a Map-Resolver is used that is not a Map-Server for the EID-prefix
being sought, then the ALT infrastructure can be tested. This test
case is testing the functionality of the Map-Resolver, traversal of
the ALT (testing BGP-over-GRE), and the Map-Server.
It is recommended that users issue 2 lig requests, each of which send
Map-Requests to different Map-Resolvers.
The network can have a LISP-ALT router deployed as a "ALT looking-
glass" node. This type of router has BGP peering sessions with other
ALT routers where it does not inject any EID-prefixes into the ALT
but just learns ones advertised by other ALT routers and Map-Servers.
This router is configured as a Map-Resolver. Lig users can point to
the ALT looking-glass router for Map-Resolver services via the "to
<map-resolver>" parameter on the lig command. The ALT looking-glass
node can be used to lig other sites as well as your own site. When
the ALT looking-glass is used as a Map-Resolver, you can be assured
the ALT network is being tested.
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6. Future Enhancements
When negative Map-Replies have been further developed and
implemented, lig should be modified appropriately to process and
clearly indicate how and why a negative Map-Reply was received.
Negative Map-Replies could be sent in the following cases, the lig
request was initiated for a non-EID address or the Map-Request
initiated by lig request is being rejected due to rate-limiting on
the replier.
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7. Deployed Network Diagnostic Tools
There is an web-based interface to do auto-polling with lig on the
back-end for most of the LISP sites on the LISP test network. The
web-page can be accessed at http://www.lisp4.net/status.
There is a LISP site monitoring web-based interface that can be found
at http://www.lisp4.net/lisp-site.
At http://baldomar.ccaba.upc.edu/lispmon, written by the folks at
UPC, shows a geographical map indicating where each LISP site
resides.
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8. Security Considerations
The use of lig does not affect the security of the LISP
infrastructure as it is simply a tool that facilities diagnostic
querying. See [LISP], [ALT], and [LISP-MS] for descriptions of the
security properties of the LISP infrastructure.
Lig provides easy access to the information in the public mapping
database. Therefore, it is important to protect the mapping
information for private use. This can be provided by disallowing
access to specific mapping entries or to place such entries in a
private mapping database system.
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9. IANA Considerations
This document makes no request of the IANA.
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10. References
10.1. Normative References
[INTERWORK]
Lewis, D., Meyer, D., Farinacci, D., and V. Fuller,
"Interworking LISP with IPv4 and IPv6",
draft-ietf-lisp-interworking-02.txt (work in progress).
[LISP] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol (LISP)",
draft-ietf-lisp-15.txt (work in progress).
[LISP-MS] Farinacci, D. and V. Fuller, "LISP Map Server",
draft-ietf-lisp-ms-11.txt (work in progress).
[RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing
(CIDR): The Internet Address Assignment and Aggregation
Plan", BCP 122, RFC 4632, August 2006.
10.2. Informative References
[ALT] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "LISP
Alternative Topology (LISP-ALT)",
draft-ietf-lisp-alt-08.txt (work in progress).
[CONS] Farinacci, D., Fuller, V., and D. Meyer, "LISP-CONS: A
Content distribution Overlay Network Service for LISP",
draft-meyer-lisp-cons-04.txt (work in progress).
[LISP-LIG]
Farinacci, D. and D. Meyer, "LISP Internet Groper (LIG)",
draft-farinacci-lisp-lig-02.txt (work in progress).
[NERD] Lear, E., "NERD: A Not-so-novel EID to RLOC Database",
draft-lear-lisp-nerd-08.txt (work in progress).
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Appendix A. Acknowledgments
Thanks and kudos to John Zwiebel, Andrew Partan, Darrel Lewis, and
Vince Fuller for providing critical feedback on the lig design and
prototype implementations. These folks as well as all the people on
lisp-beta@external.cisco.com who tested lig functionality and
continue to do so, we extend our sincere thanks.
This working group draft is based on individual contribution
draft-farinacci-lisp-lig-02.txt [LISP-LIG].
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Authors' Addresses
Dino Farinacci
cisco Systems
Tasman Drive
San Jose, CA 95134
USA
Email: dino@cisco.com
Dave Meyer
cisco Systems
170 Tasman Drive
San Jose, CA
USA
Email: dmm@cisco.com
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