LISP Deployment Scenarios

1
LISP Deployment Scenarios

• Darrel Lewis
• and
• Margaret Wasserman
• IETF 76, Hiroshima, Japan

2
Agenda

• Introduction Deployment scenario implication
  for the LISP Specification
• Survey of LISP Network Elements
• XTRs
• Map Servers
• Map Resolvers
• Proxy ITRs
• Proxy ETRs
• Gauge level of interest in developing an
  informational draft

3
Introduction

• The goal of this presentation is to inform the
  community about how we are expecting LISP to be
  deployed
• Help to bound the discussion within practical
  scenarios
• Covers cases we expect to be most common, not all
  possibilities are covered
• For each element well discuss possible
  deployment scenarios
• And hopefully the tradeoffs
• For each element well discuss the impact of
  deployment scenarios on the spec

4
LISP xTRs as the CE
5
LISP xTRs

• xTRs at customer premise (CE)
• Advantages
• Site control of egress TE
• Site control of ingress TE
• Encapsulate last, Decapsulate first
• Disadvantages
• None?
• Spec implications
• LISP needs to work on typical CPE hardware
• Higher-end routers for mid-to-large enterprise
• Lower-end routers/CPE devices for SOHO

6
LISP xTRs (cont)

• ITR and ETR split into different devices for a
  site
• Advantages
• Best path vs. shortest path
• Disadvantages
• Additional mechanism (such as OSPF) needed for
  ITRs to detect ETR liveness
• Site must carry full routes
• Spec implications
• Need for functional separation of ITR/ETR

7
Split ITR/ETR Site
lt- Decapsulate
Encapsulate -gt
3G Provider 3.0.0.0/8
Provider A 1.0.0.0/8
1.0.0.1
ITR
LISP EID-prefix 10.0.0.0/8
ETR
iBGP
4G Provider 4.0.0.0/8
Provider B 2.0.0.0/8
2.0.0.1
ETR
ITR
8
LISP xTRs

• xTRs at the Provider Edge (PE)
• Advantages
• Site doesnt have to upgrade CE
• Multi-homing to a single SP might work
• Degenerate of the VPN case local NAT in
• Disadvantages
• Site loses control of egress TE
• Locator liveness is problematic
• Implications
• LISP would need to work on typical PE hardware

9
LISP xTRs (cont)

• xTRs for Inter-Service Provider TE
• Advantages
• Separate mapping database shared between service
  providers
• Bilateral agreements allow traffic engineering
  across multiple MPLS ASes
• Disadvantages
• Extra header, addl looked, database maintenance
• Implications
• Requires support for two levels of LISP headers

10
Map Server

• Authenticated Map Register messages are sent to
  Map Servers by ETRs
• Map Server(s) will probably be provided by an EID
  registrar
• Redundant servers are desirable
• Impacts
• Need mechanism to configure EID prefix(es), keys
  and map server address(es) on ETRs

11
Map Resolver

• Map Requests are sent to Map Resolvers by ITRs
• Map resolvers will probably be provided by
  Internet Service Providers
• Impacts
• Need DHCP option or other mechanism to configure
  map resolver address(es) on ITRs

12
Proxy-ITRs
65.0.0.0/12
66.3.3.3
66.0.0.0/12
Legend LISP Sites -gt Green (and EIDs)
non-LISP Sites -gt Red (and RLOCs) xTR
Infrastructure Solution
13
LISP Proxy-ITRs

• Advantages
• Allow connectivity between LISP nodes and
  non-LISP nodes
• Early Adopter LISP sites see benefits of LISP
• Disadvantages
• Non-LISP traffic may take suboptimal route
  through Proxy ITR (compared to LISP-NAT)
• Implications
• Defined in Interworking specification

14
Proxy-ETRs
(1)
(2)
65.1.1.1 lt-1.1.1.1
65.10.1.1
Encapsulate
P-ETR
65.9.1.1
Encapsulate
BGP Advertise 1.0.0.0/8
65.9.2.1
65.0.0.0/12
BGP Advertise 1.0.0.0/8
66.3.3.3
66.0.0.0/12
Legend LISP Sites -gt Green (and EIDs)
non-LISP Sites -gt Red (and RLOCs) xTR
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LISP Proxy-ETRs

• Advantages
• Allows LISP nodes in sites with URPF restrictions
  to communicate with non-LISP nodes
• Allows LISP in sites without natvie IPv6 support
  to communication with LISP nodes that have only
  v6 RLOCs
• Can (should?!) be separate devices from
  Proxy-ITRs
• Disadvantages
• Packets may take longer path through P-ETR
• Implications
• Defined in Interworking specification

16
Early Adopter/Experimental

• xTRs behind a NAT
• Advantages
• Allows LISP connectivity to/from sites behind a
  NAT for test network/early deployment
• Disadvantages
• Somewhat Complex to configure
• Implications
• Limited NAT traversal needed
• 1 xTR at global address, static port forwarding
  for 4341 4342
• Dynamic Locator in ETR Database
• Needed for short term, when LISP is not
  integrated with provider-supplied CPE

17
Wrap UP

• Is further work needed in this area?
• Should we write an informational draft?