Network Working Group                                       D. Farinacci
Internet-Draft                                                  D. Meyer
Intended status: Experimental                              cisco Systems
Expires: October 12, 2010 April 10, 14, 2011                                 October 11, 2010

                       LISP Internet Groper (LIG)


   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.

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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.  Deployed Network Diagnostic Tools  . . . . . . . . . . . . . . 14
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 16
     10.2. Informative References . . . . . . . . . . . . . . . . . . 16
   Appendix A.  Acknowledgments . . . . . . . . . . . . . . . . . . . 17
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18

1.  Requirements Notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

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

   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

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.

   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.

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

   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
   site as well as from infrastructure hosts to get mapping information.

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
     Send map-request to for ...
     Received map-reply from with rtt 0.081468 secs

     Map-cache entry for EID, uptime: 13:59:59, expires: 23:59:58,
                     via map-reply, auth
       Locator          Uptime    State  Priority/Weight  Packets In/Out         13:59:59  up     1/100            0/14

   Using lig to "lig yourself" is accomplished with the following

       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
   is, the destination-EID for the Map-Request is  The source-EID address for the Map-Request will also be (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 for ...
     Received map-reply from with rtt 0.001592 secs

     Map-cache entry for EID, uptime: 00:00:02, expires: 23:59:57
                     via map-reply, self
       Locator       Uptime    State  Priority/Weight  Packets In/Out      00:00:02  up     1/100            0/0

     titanium-simlo# lig self6
     Send loopback map-request to 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         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.

       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 -m
     Send map-request to for ...
     Received map-reply from with rtt 0.04000 sec

     Mapping entry for EID, record ttl: 60
      Locator           State     Priority/Weight          up        1/25          up        1/25          up        1/25          up        2/25

   The public domain implementation of lig is available at

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.

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.

8.  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

   There is a LISP site monitoring web-based interface that can be found

   At, written by the folks at
   UPC, shows a geographical map indicating where each LISP site

9.  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.

10.  References

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

10.2.  Informative References

   [ALT]      Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "LISP
              Alternative Topology (LISP-ALT)",
              draft-ietfr-lisp-alt-04.txt (work in progress),
              April 2010.

   [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-ietf-lisp-09.txt (work in progress), April October 2010.

              Farinacci, D. and D. Meyer, "LISP Internet Groper (LIG)",
              draft-farinacci-lisp-lig-02.txt (work in progress),
              February 2010.

   [LISP-MS]  Farinacci, D. and V. Fuller, "LISP Map Server",
              draft-ietf-lisp-ms-05.txt (work in progress), April 2010.

   [NERD]     Lear, E., "NERD: A Not-so-novel EID to RLOC Database",
              draft-lear-lisp-nerd-04.txt (work in progress),
              April 2008.

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 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].

Authors' Addresses

   Dino Farinacci
   cisco Systems
   Tasman Drive
   San Jose, CA  95134


   Dave Meyer
   cisco Systems
   170 Tasman Drive
   San Jose, CA