1. NAT Traversal for LISP Mobile Node
Dominik Klein, Matthias Hartmann, and
Michael Menth

2. Overview Problem: Communication through NAT
Solution: NAT traversal mechanism
Idea
Flow charts
Summary & discussion

3. Problem: Communication through NAT
Observation
MN roams in domain with private addresses
Problem
MN registers private address as RLOC at mapping service
MN reachable only within own domain MS
Internet
LISP
domain
Non-LISP
domain
NAT MN
EID 1 ?
ITR/ETR
RLOC B SN
EID 2
Src:
Dest:
RLOC B
11792
4341
EID 2
EID 1
DATA
Src:
Dest:
EID 2
EID 1
DATA
OH:
UDP:
IH:

4. Solution: NAT Traversal Router
NAT traversal router (NTR)
NTR collocated with map server (MS)
MN registers at NTR
NTR adds own RLOC for MN in MS
Traffic from outside tunneled from NTR to MN through NAT MS
Internet
Non-LISP
domain MN
EID 1
NTR
RLOC N
Traffic for MN
NAT

5. Registration Process Internet Non-LISP domain Src: Dest: 10.0.0.1
Internal IP:Port External IP:Port Peer IP:Port
: : RLOC N:4342
EID-to-IP:Port Mapping
EID :20321
EID-to-RLOC Mapping
EID RLOC N MS
Internet
Non-LISP
domain MN
EID 1
NTR
RLOC N
NAT
Src:
Dest:
RLOC N
4341
4342
REGISTRATION:
EID 1 
Src:
Dest:
RLOC N
20321
4342
REGISTRATION:
EID 1 
OH:
UDP:
LISP:

6. Incoming Traffic Internet LISP Non-LISP domain domain Src: Dest:
Internal IP:Port External IP:Port Peer IP:Port
: : RLOC N:4342
EID-to-IP:Port Mapping
EID :20321
EID-to-RLOC Mapping
EID RLOC N MS
LISP
domain
Internet
Non-LISP
domain MN
EID 1
ITR/ETR
RLOC B
NTR
RLOC N SN
EID 2
NAT
Src:
Dest:
RLOC N
4342
4341
EID 2
EID 1
DATA
Src:
Dest:
RLOC N
4342
20321
EID 2
EID 1
DATA
Src:
Dest:
RLOC B
RLOC N
30369
4341
EID 2
EID 1
DATA
Src:
Dest:
EID 2
EID 1
DATA
OH:
UDP:
IH:

7. Outgoing Traffic Observation
NTR not necessarily required as relay for outgoing traffic
Example: MN sends traffic to stationary node in other LISP domain using a direct tunnel to destination ETR
LISP
domain
Internet
Non-LISP
domain MN
EID 1
ITR/ETR
RLOC B SN
EID 2
NAT
Src:
Dest:
RLOC B
11987
4341
EID 1
EID 2
DATA
Src:
Dest:
RLOC B
11987
4341
EID 1
EID 2
DATA
Src:
Dest:
EID 1
EID 2
DATA
OH:
UDP:
IH:

8. Summary & Discussion Mobile nodes not reachable behind NAT
NAT traversal router (NTR) helps
Receives traffic for MN
Relays it through the NAT to the MN
Protocol implementation in Omnet++
Discussion
Great for MN reachability?  Standardize it!
Security risk?  How to avoid it?

9. References LISP (http://tools.ietf.org/html/draft-ietf-lisp-05)
LISP-MN (
LISP-INT (
Most recent version published on LISP mailing list (
LISP-NAT paper (
LISP-NAT draft (