Network Working Group D. Farinacci
Internet-Draft D. Meyer
Intended status: Experimental cisco Systems
Expires: November 6, 2009 May 5, 2009
LISP Internet Groper (LIG)
draft-farinacci-lisp-lig-01.txt
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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.
Table of Contents
1. Requirements Notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 5
4. Basic Overview . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Implementation Details . . . . . . . . . . . . . . . . . . . . 9
5.1. LISP Router Implementation . . . . . . . . . . . . . . . . 9
5.2. Public Domain Host Implementation . . . . . . . . . . . . 10
6. Testing the ALT . . . . . . . . . . . . . . . . . . . . . . . 12
7. Future Enhancements . . . . . . . . . . . . . . . . . . . . . 13
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . . 15
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
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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].
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2. 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 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, PTR, 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.
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3. 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; where the topology is defined by the connectivity of
provider networks, 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 an destination address
today, for example through a DNS lookup or SIP exchange. 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, PTR, 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.
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4. 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 usage 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 lig initiating site is displayed for the user.
Refer to the syntax in section Section 5.1 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 can be used in a non-LISP
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site as well as from infrastructure hosts to get mapping information.
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5. Implementation Details
5.1. 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:
titanium-dino# lig titanium-dmm.lisp4.net
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 titanium-dmm.lisp4.net 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 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:
rutile# 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
titanium-simlo# lig self6
Send loopback map-request to 10.0.0.1 for 192:168:1:: ...
Received map-reply from 10::1 with rtt 0.044372 secs
Map-cache entry for EID 192:168:1:::
192:168:1::/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
10::1 00:00:01 up 2/0 0/0
5.2. 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 titanium-test.lisp4.net -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
sourceforge.net.
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6. 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 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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7. 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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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.
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9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
9.2. Informative References
[ALT] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "LISP
Alternative Topology (LISP-ALT)",
draft-fuller-lisp-alt-03.txt (work in progress),
February 2009.
[CONS] Farinacci, D., Fuller, V., and D. Meyer, "LISP-CONS: A
Content distribution Overlay Network Service for LISP",
draft-meyer-lisp-cons-03.txt (work in progress),
November 2007.
[LISP] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol (LISP)",
draft-farinacci-lisp-12.txt (work in progress),
March 2009.
[LISP-MS] Farinacci, D. and V. Fuller, "LISP Map Server",
draft-fuller-lisp-ms-00.txt (work in progress),
March 2009.
[NERD] Lear, E., "NERD: A Not-so-novel EID to RLOC Database",
draft-lear-lisp-nerd-04.txt (work in progress),
April 2008.
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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.
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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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