LISP Deployment Scenarios
Darrel Lewis
and
Margaret Wasserman
IETF 76, Hiroshima, Japan
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
Slide 2
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 we’ll discuss possible deployment
scenarios
– And hopefully the tradeoffs
• For each element we’ll discuss the impact of
deployment scenarios on the spec
Slide 3
LISP xTRs as the CE
Internet
Provider A
10.0.0.0/8
Provider B
11.0.0.0/8
R1
R2
BGP
Provider Independent (PI)
15.0.0.0/8
Slide 4
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
Slide 5
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
Slide 6
Split ITR/ETR Site
<- Decapsulate
Encapsulate ->
S3
LISP
EID-prefix
10.0.0.0/8
S1
ITR
S4
ITR
3G Provider
3.0.0.0/8
ETR
iBGP
S
Provider A
1.0.0.0/8
S2
Provider B
2.0.0.0/8
4G Provider
4.0.0.0/8
ETR
Slide 7
LISP xTRs
• xTRs at the Provider Edge (PE)
– Advantages
• Site doesn’t 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
Slide 8
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, add’l looked, database maintenance
– Implications
• Requires support for two levels of LISP headers
Slide 9
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
Slide 10
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
Slide 11
Proxy-ITRs
(2)
(1)
65.9.1.1 -> 66.1.1.1
65.1.1.1 -> 1.1.1.1
R-prefix
65.1.0.0/16
65.1.1.1 -> 1.1.1.1
NR-prefix
1.1.0.0/16
P-ITR
BGP Advertise:
1.0.0.0/8
R-prefix
65.2.0.0/16
P-ITR
BGP Advertise:
1.0.0.0/8
P-ITR
R-prefix
65.3.0.0/16
BGP Advertise:
1.0.0.0/8
NR-prefix
1.2.0.0/16
(3)
1.1.1.1 -> 65.1.1.1
65.0.0.0/12
66.0.0.0/12
NR-prefix
1.3.0.0/16
Legend:
Infrastructure Solution
LISP Sites -> Green (and EIDs)
non-LISP Sites -> Red (and RLOCs)
xTR
Slide 12
LISP Proxy-ITRs
• Advantages
– Allow connectivity between LISP nodes and nonLISP 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
Slide 13
Proxy-ETRs
(1)
65.10.1.1 <- 66.1.1.1
(2)
65.1.1.1 <-1.1.1.1
65.1.1.1 <- 1.1.1.1
R-prefix
65.1.0.0/16
R-prefix
65.2.0.0/16
NR-prefix
1.1.0.0/16
P-ETR
NR-prefix
1.2.0.0/16
P-ITR
BGP Advertise:
1.0.0.0/8
P-ITR
R-prefix
65.3.0.0/16
BGP Advertise:
1.0.0.0/8
65.0.0.0/12
66.0.0.0/12
NR-prefix
1.3.0.0/16
Legend:
LISP Sites -> Green (and EIDs)
non-LISP Sites -> Red (and RLOCs)
xTR
Slide 14
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 ProxyITRs
• Disadvantages
– Packets may take longer path through P-ETR
• Implications
– Defined in Interworking specification
Slide 15
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
Slide 16
Wrap UP
• Is further work needed in this area?
• Should we write an informational
draft?
Slide 17