1. CCM 4300 Lecture 8
Computer Networks: Wireless and Mobile Communication Systems
Dr E. Ever
School of Computing Science

2. Mobility and IP …… more information
Mobile Wireless Internet Forum •
IPv6 work including mobility support
"The 3G IP Multimedia Subsystem" by Gonzalo Camarillo and Miguel A. Garcia Martin (available in google books)

3. Facts about Mobile IP More than 2 billion subscribers
More than 70% of all digital mobile phones use GSM
7.3 million people accesses the net via their mobile phones, during the second and third quarters of (BBC news channel)
An increase of 25% compared to growth of juts 3% for the PC based net audience-(BBC news channel)
IPv4 can do it all, it will be at a tremendous (unimaginable) cost and complexity
Only IPv6 offers enough addresses
IPv6 offers features needed for mobile networking
IPv6 utilises features to offer seamless roaming
Network layer roaming enables cost reduction and improve deploy ability

4. Lesson objectives -Security in MIP
To acquire a basic understanding of the basics of Mobile IPv4 and IPv6, you will:
- Understand principles of network MIP and HMIP:
HA, CN, MN, FN, HN, FA, binding updates, CoA, RCoA.
Triangular rule
Route optimisation
Availability and access control.
-Security in MIP
Key distribution
Home Agent (HA)
Correspondent Node (CN)
Mobile Node (MN)
Foreign Network(FN)
Home Network(HN)
Foreign Agent (FA)
Care-of Address (COA)

5. Mobile Network layer • Mobile phone • Mobile IP (Internet Protocol)
• Hand-off effects:
• addressing and routing
• operation of upper layer protocols
Mobile IPv6

6. Why Mobile IP
Routing
Both ends of TCP (connection) need to keep the same IP address for the life of the session (home address, end-end)
change of physical subnet implies change of IP address to have a topological correct address (standard IP) or needs special entries in the routing tables (care-of-address, routing
Specific routes to end-systems?
change of all routing table entries to forward packets to the right destination
does not scale with the number of mobile hosts and frequent changes in the location, security problems
Changing the IP-address?
adjust the host IP address depending on the current location (managing a binding)
almost impossible to find a mobile system, DNS updates take a long time (dynamic tunnel between CoA & HA)
TCP connections break, security problems!!!!

7. Requirements for Mobile IP
Transparency
mobile end-systems keep their IP address
continuation of communication after interruption of link possible
point of connection to the fixed network can be changed
Compatibility
support of the same layer 2 protocols as IP
no changes to current end-systems and routers required
mobile end-systems can communicate with fixed systems
Security
authentication of all registration messages
Efficiency and scalability
only little additional messages to the mobile system required (connection typically via a low bandwidth radio link)
world-wide support of a large number of mobile systems in the whole Internet

8. Mobile IP: Terminology
Mobile Node (MN)
system (node) that can change the point of connection to the network without changing its IP address
Home Agent (HA)
system in the home network of the MN, typically a router
registers the location of the MN, tunnels IP datagrams to the COA
Foreign Agent (FA)
system in the current foreign network of the MN, typically a router
forwards the tunneled datagrams to the MN, typically the default router for the MN
Care-of Address (COA)
address of the current tunnel end-point for the MN (at FA or MN)
temporary IP address for a mobile device
allows a home agent to forward messages to the mobile device.
separate address is required because the IP address of the device that is used as host identification is topologically incorrect
actual location of the MN from an IP point of view, can be chosen, e.g., via DHCP
Correspondent Node (CN)
communication partner

9. How can IP support mobile connectivity?
Key Question
How do mobile hosts maintain IP connectivity
when mobility is supported at layer 3?
Here we investigate two extensions to IPv4.
As mobile computing devices increase in capability
mobile communication becomes increasingly wide-spread.
THE BIG QUESTION IS:
How can IP support mobile connectivity?

10. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
Mobile IP: An Overview
COA
foreign
network
router FA MN
home
network
router HA
Internet CN
router
foreign
network 3.
router FA MN
home
network
router HA 2. 4.
Internet 1. CN
router
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

11. Mobile Phone network routing
During call
• Hand-off:
• within area: BTS  BTS
• between areas: BSC  BSC, MSC informed of move to different area
• MSC  MSC: updates to
HLR/VLR
• Call maintained during hand-off:
• only last-hop link
• Transparent to user:
• momentary signal loss(?)
Call set-up
• MS emits beacon:
• IMSI/IMEI unique ID
• beacon heard by BTS
• BTS  BSC  MSC
• MSC:
• HLR
• VLR
• updates HLR/VLR
• if VLR updated, sends info
to home network for MS
• Network always knows location of MS
IMSI: international mobile subscriber identity
IMEI: international mobile equipment identity

12. Data transfer to the mobile system
Triangular
home network
foreign
network HA 2 FA MN
receiver 3 1
Internet
sender CN
1. Sender sends to the IP address of MN,
HA intercepts packet
2. HA tunnels packet to COA, here FA,
by encapsulation
3. FA forwards the packet to the MN

13. Data transfer from the mobile system
home network
foreign network HA FA 1 MN
sender
Internet
receiver CN
1. Sender sends to the IP address of the receiver as usual, FA works as default router

14. Mobile phone network routing
Internet
sender FA HA MN
home network
foreign
network
receiver 1 2 3
1. Sender sends to the IP address of MN,
HA intercepts packet (proxy ARP)
2. HA tunnels packet to COA, here FA,
by encapsulation
3. FA forwards the packet to the MN CN

15. Mobile IP (1) • Need to support mobile users: • Mobile host (MH):
• Transparency:
• to upper layers
• to remote end-systems
• IPv4: IP address indicates
point of attachment to Network
• Movement of host means:
• new IPv4 address?
• update routing information?
• Mobile host (MH):
• home network (HN), home agent (HA)
• foreign network (FN),
foreign agent (FA)
• care-of-address (CoA)
• Communication:
• HA sends packets to CoA:
IP-in-IP encapsulation
• must reply to ARP for MH
• CoA:
• may be new IP address
• foreign agent

16. Mobile IP (2)
1) MH arrives at FN, and locates FA (using agent advertisements from FA or by solicitation).
2) MH completes registration procedure with FA.
3) MH updates HA with its new CoA (i.e. the FA).
4) Host A now tries to contact MH. Packets for MH are intercepted by HA
5) HA tunnels the packets from Host A to the CoA for MH
(i.e. the FA)
6) The FA de-encapsulates the inner IP packet and transmits
the packet locally to MH.
7) The packets from MH to Host A are sent directly from the FN.

17. Mobile IP (2) 4 5 7 2 3 6 1 Host A HA IP-in-IP encapsulation FA MH
home network
Host A
remote network FA
foreign network
Internet MH 1 2 3 4 5 6 7
Data
src = Host A
dst = MH
dst = MN
IP-in-IP encapsulation

18. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
Encapsulation
original IP header
original data
new IP header
new data
outer header
inner header
original data
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

19. Mobile IP (3)  Transparent to non-mobile hosts
 Does not break/change existing IP addressing and routing
 Can be introduced into the network as required
 Normal (unicast) routers do not need to be modified
X Asymmetric routing:
Packets flowing in i.e. TCP connections flow through different routes to different directions.
• could be inefficient
• QoS
• higher layer protocol operation (e.g. TCP)
X Security:
• firewalls have to be (dynamically) configured
• authentication:
MH  FN(?), FA  HA(?)
MH  HA
• end-to-end security?
X Hand-off between FAs or FA/HA:
• lost packets(?)

20. Registration t MN HA
registration
request
reply FA

21. Handoffs: layer 2 versus Layer 3
• No global changes:
• only local last hop
• No routing at layer 2
• No global addressing
significance at layer 2
• Need to have same layer 2
technology across network
• Mobility within network:
• no hand-off between network technologies
Register a new IP
Layer 3
• Global, end-system to end-system connectivity
• Addresses have global significance
• Change in layer 3 address is change to network
• Layer 3 address valid across different layer 2 technologies
• Mobility across networks:
• internetworking!
Register an FA only

22. TCP behaviour (1) Problems • Layer 2 cell hand-off:
• data loss /corruption (also due to high BER in general)
• no ACK for data
• TCP:
• no ACK  slow start
• TCP has degraded performance
• High BER on wireless link (~ ~10-4 common):
• corrupt data requires end-to-end re-tx (use layer 2 FEC)
• Affects other transport-layer or application-layer protocols:
• real-time applications – errors and packet loss are harmful

23. TCP behaviour (2) Possible solutions
• TCP SACK option: (selective acknowledgment)
• retransmission of missing “holes” in byte stream
• not always implemented
• Use ECN in IP: (explicit congestion notification)
• need to modify TCP interface and applications
• Link-local re-tx:
• on wireless hop
• need to hold TCP, e.g. at base station
• need re-tx protocol
• Soft hand-off at layer 2: (a cell phone is simultaneously connected to two or more cells during a call.)
• need to use CDMA, which has its own problems

24. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
Network integration
Agent Advertisement
HA and FA periodically send advertisement messages into their physical subnets
MN listens to these messages and detects, if it is in the home or a foreign network (standard case for home network)
MN reads a COA from the FA advertisement messages
Registration (always limited lifetime!)
MN signals COA to the HA via the FA, HA acknowledges via FA to MN
these actions have to be secured by authentication
Advertisement
HA advertises the IP address of the MN (as for fixed systems), i.e. standard routing information
routers adjust their entries, these are stable for a longer time (HA responsible for a MN over a longer period of time)
packets to the MN are sent to the HA,
independent of changes in COA/FA
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

25. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
Encapsulation I
Encapsulation of one packet into another as payload
e.g. IPv6 in IPv4 (6Bone), Multicast in Unicast (Mbone)
here: e.g. IP-in-IP-encapsulation, minimal encapsulation or GRE (Generic Record Encapsulation)
IP-in-IP-encapsulation (mandatory, RFC 2003)
tunnel between HA and COA
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

26. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
Encapsulation II
Minimal encapsulation (optional)
avoids repetition of identical fields
e.g. TTL, IHL, version, DS (RFC 2474, old: TOS)
only applicable for unfragmented packets, no space left for fragment identification
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

27. Generic Routing Encapsulation
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
Generic Routing Encapsulation
An example:
original
header
original data
new data
new header
outer header
GRE header
original header
RFC 1701
ver.
IHL
DS (TOS)
length
IP identification
flags
fragment offset
TTL
GRE
IP checksum
RFC 2784
IP address of HA
Care-of address COA C R K S s
rec.
rsv.
ver.
protocol C
reserved0
ver.
protocol
checksum (optional)
offset (optional)
checksum (optional)
reserved1 (=0)
key (optional)
sequence number (optional)
routing (optional)
ver.
IHL
DS (TOS)
length
IP identification
flags
fragment offset
TTL
lay. 4 prot.
IP checksum
IP address of CN
IP address of MN
TCP/UDP/ ... payload
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

28. Optimisation of packet forwarding
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
Optimisation of packet forwarding
Triangular Routing
sender sends all packets via HA to MN
higher latency and network load (for each RTT)
“Solutions”
sender learns the current location of MN (give away your position!)
direct tunneling to this location
HA informs a sender about the location of MN
big security problems!
Change of FA
packets on-the-fly during the change can be lost
new FA informs old FA to avoid packet loss (chaining), old FA now forwards remaining packets to new FA
this information also enables the old FA to release resources for the MN
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

29. Change of the foreign agent with the optimized mobile IP
Direct tunneling is used. HA only provides information about FA CN HA
FAold
FAnew MN t
request
update
ACK
data
data
MN changes location
registration
registration
update
data
ACK
data
data
warning
update
ACK
data
data

30. Change of foreign agent
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
Change of foreign agent CN HA
FAold
FAnew MN
Data
Data
Data
Update
ACK
Data
Data
MN changes location
Registration
Update
ACK
Data
Data
Data
Warning
Request
Update
ACK
Data
Data t
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

31. Reverse Tunneling (RFC 2344)
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
Reverse Tunneling (RFC 2344)
Mobile Internet Protocol (IP) uses tunneling from the home agent to the mobile node's care-of address, but rarely in the reverse direction.
Usually, a mobile node sends its packets through a router on the foreign network, and assumes that routing is independent of source address.
When this assumption is not true (it is not feasible or desired to have the mobile node send datagrams directly to the internetwork using FA), it is convenient to establish a topologically correct reverse tunnel from the care-of address to the home agent.
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

32. Reverse tunneling: 2 1 3 HA MN FA CN 1. MN sends to FA
Internet
home network 1
sender FA
foreign network
1. MN sends to FA 3
2. FA tunnels packets to HA
by encapsulation CN
3. HA forwards the packet to the
receiver (standard case)
receiver

33. Reverse tunneling (RFC 3024, was: 2344)
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
Reverse tunneling (RFC 3024, was: 2344) HA 2 MN
Internet
home network 1
sender FA
foreign network
1. MN sends to FA
2. FA tunnels packets to HA
by encapsulation
3. HA forwards the packet to the
receiver (standard case) 3 CN
receiver
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

34. Mobile IP with reverse tunneling
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
Mobile IP with reverse tunneling
Router accept often only “topological correct“ addresses (firewall!)
a packet from the MN encapsulated by the FA is now topological correct
furthermore multicast and TTL problems solved (TTL in the home network correct, but MN is to far away from the receiver)
Reverse tunneling does not solve
problems with firewalls, the reverse tunnel can be abused to circumvent security mechanisms (tunnel hijacking)
optimization of data paths, i.e. packets will be forwarded through the tunnel via the HA to a sender (double triangular routing)
The standard is backwards compatible
the extensions can be implemented easily and cooperate with current implementations without these extensions
Agent Advertisements can carry requests for reverse tunneling
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

35. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
Mobile IP and IPv6
Mobile IP was developed for IPv4, but IPv6 simplifies the protocols
security is integrated and not an add-on, authentication of registration is included
COA can be assigned via auto-configuration (DHCPv6 is one candidate), every node has address auto configuration
no need for a separate FA, all routers perform router advertisement which can be used instead of the special agent advertisement; addresses are always co-located (any router can act like an FA)
MN can signal a sender directly the COA, sending via HA not needed in this case (automatic path optimsation)
“soft“ hand-over, i.e. without packet loss, between two subnets is supported
MN sends the new COA to its old router
the old router encapsulates all incoming packets for the MN and forwards them to the new COA
authentication is always granted
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

36. Mobile IP and IPv6 (2)
Once a MN moves into a foreign network, acquiring a new IP address - (CoA)
The MN is required to register this address with its HA via a binding update.
This binding update is issued over an IPSec tunnel, using an IPv6 security association, to protect its integrity and authenticity.

37. Mobile IPv6 Protocol: an overview
Home agent
Correspondent node
Correspondent node with binding
Local router
Advertisement from local router contains routing prefix
Seamless Roaming: MN always uses home address
Address configuration for care-of-address
Binding Updates sent to home agent & correspondent nodes (home address, care-of address, binding life time)
Mobile node ALWAYS ON by way of Home agent

38. Mobile IPv6 Design Points (why?)
Enough address (340 undecillion 1036 addresses)
Addresses in IPv6 are 128 bits long, compared to 32-bit addresses in IPv4.
The very large IPv6 address space supports a total of 2128 (about 3.4×1038) addresses
340,282,366,920,938,463,463,374,607,431,768,211,456
In China alone, there are 8 million IPv4 addresses and 70+ million handsets
Enough security (almost, not quite!)
KDC, symmetric key, managing 10 million security associates, authentication header, security payload
Address Autoconfiguration
Movement detection, Monitoring advertisement
Route Optimisation (binding updates part of IPv6)
Destination Options (binding updates and acks) no reg and reg reply

39. Other relevant issues with IP
Seamless Mobility
Paging, context transfer, micro-mobility (localised binding management)
Robust Header Compression
Reducing 40/60 bytes of header overhead to 2-3 byte
Authentication, Authorisation, and Accounting (AAA)
Smooth handover == low loss
Fast handover == low delay (approx 30 ms)
Seamless handover == smooth and fast

40. Mobile-controlled seamless handoverRS HI RA
HAck
Scenario I: mobile sends special Router Solicitation (RS)
Previous Access Router replies with proxy Router Advert (RA)
Previous Access Router sends Handover Initiate (HI)
New Access Router sends Handover Acknowledge (HACK)
kjhasj

41. Network Controlled HandoverHI
Proxy router adv
HAck
Previous access router sends Proxy Router Advertisement on behalf of the new access router – contains prefix and lifetime information …
Previous access router sends Handover Initiate message to new access router
Mobile node May finalise context transfer at new access router

42. Problems with mobile IP
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
Problems with mobile IP
Security
authentication with FA problematic, for the FA typically belongs to another organisation
no protocol for key management and key distribution has been standardised in the Internet
patent and export restrictions
Firewalls
typically mobile IP cannot be used together with firewalls, special set-ups are needed (such as reverse tunneling)
QoS
many new reservations in case of RSVP
tunneling makes it hard to give a flow of packets a special treatment needed for the QoS
Security, firewalls, QoS etc. are topics of current research and discussions!
RSVP (Resource reSerVation Protocol)
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

43. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
Security in Mobile IP
Security requirements (Security Architecture for the Internet Protocol, RFC 1825)
Integrity: any changes to data between sender and receiver can be detected by the receiver
Authentication: sender address is really the address of the sender and all data received is really data sent by this sender
Confidentiality: only sender and receiver can read the data
Non-Repudiation: sender cannot deny sending of data
Traffic Analysis: creation of traffic and user profiles should not be possible
Replay Protection: receivers can detect replay of messages
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

44. IP security architecture I
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
IP security architecture I
Two or more partners have to negotiate security mechanisms to setup a security association
typically, all partners choose the same parameters and mechanisms
Two headers have been defined for securing IP packets:
Authentication-Header
guarantees integrity and authenticity of IP packets
if asymmetric encryption schemes (Public, Private Keys) are used, non-repudiation can also be guaranteed
Encapsulation Security Payload
protects confidentiality between communication partners
Authentification-Header
IP-Header
UDP/TCP-Paket
authentication header
IP header
UDP/TCP data
not encrypted
encrypted
IP header
ESP header
encrypted data
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

45. IP security architecture II
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
IP security architecture II
Mobile Security Association for registrations
parameters for the mobile host (MH), home agent (HA), and foreign agent (FA)
Extensions of the IP security architecture
extended authentication of registration
prevention of replays of registrations
time stamps: 32 bit time stamps + 32 bit random number
Nonces (number for once pseudo random number): 32 bit random number (MH) + 32 bit random number (HA)
MH-FA authentication
FA-HA authentication
MH-HA authentication
registration request MH FA
registration request HA
registration reply
registration reply
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

46. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
Key distribution
Home agent distributes session keys
foreign agent has a security association with the home agent
mobile host registers a new binding at the home agent
home agent answers with a new session key for foreign agent and mobile node FA MH
response:
EHA-FA {session key}
EHA-MH {session key} HA
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

47. IP Micro-mobility support
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
IP Micro-mobility support
Micro-mobility support (Change FA):
Efficient local handover inside a foreign domain without involving a home agent
Reduces control traffic on backbone
Especially needed in case of route optimisation
Example approaches:
Cellular IP
HAWAII
Hierarchical Mobile IP (HMIP)
Important criteria: Security Efficiency, Scalability, Transparency, Manageability
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

48. Support for Mobility in IPv6
• Stateless address auto-configuration:
• find an address (CoA) for use at the FN
• Neighbour discovery:
• find default router
• No FA required to support mobility:
• MH takes care of home
address and foreign address
• Need dynamic DNS update support
• Route optimisation:
• send CoA to remote end-system
• Security:
• authentication and privacy

49. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
Cellular IP (CIP)
Operation:
“CIP Nodes“ maintain routing entries (soft state) for MNs
Multiple entries possible
Routing entries updated based on packets sent by MN
CIP Gateway:
Mobile IP tunnel endpoint
Initial registration processing
Security provisions:
all CIP Nodes share „network key“
MN key: MD5(net key, IP addr)
MN gets key upon registration
CIP Gateway
Internet BS
MN1
data/control
packets
from MN 1
Mobile IP
MN2
packets from
MN2 to MN 1
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

50. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
Cellular IP: Security
Advantages:
Initial registration involves authentication of MNs and is processed centrally by CIP Gateway
All control messages by MNs are authenticated
Replay-protection (using timestamps)
Potential problems:
MNs can directly influence routing entries
Network key known to many entities (increases risk of compromise)
No re-keying mechanisms for network key
No choice of algorithm (always MD5, prefix+suffix mode)
Message-Digest algorithm 5 is a widely used cryptographic hash function
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

51. Cellular IP: Other issues
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
Cellular IP: Other issues
Advantages:
Simple and elegant architecture
Mostly self-configuring (little management needed)
Integration with firewalls / private address support possible
Potential problems:
Not transparent to MNs (additional control messages)
Public-key encryption of MN keys may be a problem for resource-constrained MNs
Multiple-path forwarding may cause inefficient use of available bandwidth
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

52. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
HAWAII
Operation:
MN obtains co-located COA and registers with HA
Handover: MN keeps COA, new BS answers Reg. Request and updates routers
MN views BS as foreign agent
Security provisions:
MN-FA authentication mandatory
Challenge/Response Extensions mandatory
Backbone
Router
Internet BS MN
Crossover
DHCP
Server HA
Mobile IP 1 2 4 1 2 3 4 BS 3
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

53. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
HAWAII: Security
Advantages:
Mutual authentication and Challenge/Response extensions mandatory
Only infrastructure components can influence routing entries
Potential problems:
Co-located COA raises DHCP security issues (DHCP has no strong authentication)
Decentralised security-critical functionality (Mobile IP registration processing during handover) in base stations (BS)
Authentication of HAWAII protocol messages unspecified (potential attackers: stationary nodes in foreign network)
MN authentication requires PKI or AAA infrastructure
PKI: Public Key Infrastructure
AAA: authentication, authorization and accounting
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

54. Universität Karlsruhe Institut für Telematik
Mobilkommunikation
SS 1998
HAWAII: Other issues
Advantages:
Mostly transparent to MNs (MN sends/receives standard Mobile IP messages)
Explicit support for dynamically assigned home addresses
Potential problems:
Mixture of co-located COA and FA concepts may not be supported by some MN implementations
No private address support possible because of co-located COA
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

55. Hierarchical Mobile IPv6 (HMIPv6)
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
Hierarchical Mobile IPv6 (HMIPv6)
Operation:
Network contains mobility anchor point (MAP)
mapping of regional COA (RCOA) to link COA (LCOA)
Upon handover, MN informs MAP only
gets new LCOA, keeps RCOA
HA is only contacted if MAP changes
Security provisions:
no Hierarchical Mobile IPv6 -specific security provisions
binding updates should be authenticated
Internet HA
RCOA
MAP
binding
update AR AR
LCOAold
LCOAnew MN MN
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

56. Hierarchical Mobility Agents
Problem: how to reduce latency due to signalling Agent
Solution: localise signalling to visited Domain
How, "method": Regional Registration/Regional Binding Update

57. Hierarchical Mobile IP: Security
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
Hierarchical Mobile IP: Security
Advantages:
Local COAs can be hidden, which provides some location privacy
Direct routing between CNs sharing the same link is possible (but might be dangerous)
Potential problems:
Decentralised security-critical functionality (handover processing) in mobility anchor points
MNs can (must!) directly influence routing entries via binding updates (authentication necessary)
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

58. Hierarchical Mobile IP: Other issues
Universität Karlsruhe
Institut für Telematik
Mobilkommunikation
SS 1998
Hierarchical Mobile IP: Other issues
Advantages:
Handover requires minimum number of overall changes to routing tables
Integration with firewalls / private address support possible
Potential problems:
Not transparent to MNs
Handover efficiency in wireless mobile scenarios:
Complex MN operations
All routing reconfiguration messages sent over wireless link
Prof. Dr. Dr. h.c. G. Krüger
E. Dorner / Dr. J. Schiller

59. Other features (for IPv6 or seamless h/o)
integration of Regional Registration with GPRS
Header compression
Buffer management
UDP Lite
AAA HLR adaptation layer
Challenge generation (optionally from HLR)
Privacy considerations
QoS handover
Smooth handover mechanisms for keys