Download Routing Issues in Mobile IP

Routing Issues in Mobile IP
Sudarshan Vasudevan
Chun Zhang
PART 1
Unicast Routing using Mobile IP
Terminology
Care-of-Address
Tunneling
DHCP (Dynamic Host Configuration Protocol)
HA - Home Agent
 FA - Foreign Agent
MH - Mobile Host
 CH - Correspondent Host
1. Overview
Mobile IP
Provide Host Migration Transparency
small modifications to IP routing is sufficient
Involves 3 basic functions
Advertisement
Registration
Tunneling
Protocol
When MH is in its home network
Normal IP Routing
When MH is away from it home network
HA keeps track of MH’s care-of-address
either FA’s IP address or one obtained using DHCP
Care-of-Address represents the MH’s current
location
When the MH migrates into another foreign
network, MH notifies its new care-of-address to
the HA
Example
HA
CH
MH
FA
MH
Ha
n
d-O
ff /
Ro
am
ing
Wired backbone network
Tunneling & Triangular Routing
Normal IP
datagram
Destined for MH
141.223.84.1
HA
CH
Tunneling
Datagram
Tu
nn
el
Data Entry for HA
Data Entry for HA
Foreign MH entry
141.223.84.60 = 0F:0F:0F:0F:0F:0F
ARP cache Entry of FA for MH
141.223.84.60 = 00:00:00:00:00:00
Remote MH entry
IP address
Care-of-Address
141.223.84.60
141.223.120.1
141.223.120.1
FA
141.223.84.60
Data Entry for MH
MH
ARP cache Entry of MH
141.223.120.1 = FF:FF:FF:FF:FF:FF
141.223.84.60 = 0F:0F:0F:0F:0F:0F
Tunneling & Triangular Routing
141.223.84.1
HA
Encapsulation
nn
e
l
Triangular Route
Tu
CH
IP header
IP payload
141.223.120.1
FA
text
IP payload
IP-within-IP Encapsulation
Decapsulation
141.223.84.60
MH
new IP header
IP header
Route Optimization
Triangular path is not optimal route
Route Optimization
Supply binding update to CHs
authentication and replay protection for binding
updates
registration key between MH and FA for smooth
handoff
Route Optimization
Cache the current
care-of-address of MH
Binding Update
HA
CH
FA1
MH
After Binding Update
Smooth Hand-Off
Cache the current
care-of-address of MH
(4) Binding Update
HA
CH
Control
Packet Flow
(3) Binding
warning
FA1
(2) Binding
update to FA1
(2) Register
with HA
FA2
(1) Register
with FA
Hand-Off
MH
MH
Conclusion
Triangular Routing can be eliminated
sending binding updates to CHs
Smooth handoffs very valuable
counteract unwanted effects of dropped packets
special tunnels can further reduce this effect
Main difficulty
establishment of security associations between FA
and MH
Future Work
Mobility Security Association Management
authentication of all messages that affect routing
currently manual establishment of MSAs
difficult to manage, no scalability
 efficient Key Distribution Protocols needed
Certification of Foreign Agents
prevent malicious nodes pretending as FAs
Security issues introduced by Tunneling
References










Perkins, Charles E., ed. “Ipv4 Mobility Support” RFC 2002. October 1996b.
Perkins, Charles E. “Minimal Encapsulation within IP”. RFC 2004.October 1996c.
Perkins, Charles E. “IP Encapsulation within IP”. RFC 2003. October 1996a.
Perkins, Charles E and Johnson, David B. “Mobility Support in IPv6.” In ACM Mobicomm9
6. November 1996.
Johnson, David B. “Scalable and Robust Internetwork Routing for Mobile Hosts” In Proceedi
ngs of the 14th International Conference on Distributed Computing Systems. June 1994.
Hanks Stan, Tony Li, Dino Farinacci, and Paul Traina,Generic Routing Encapsulation over IP
v4 networks. RFC 1702. October 1994b.
Deering, Stephen E., ed., “ICMP Router Discovery Messages.” RFC 1256. September 1991.
Hellman, M.E., W.Diffie, and R.C. Merkle. “Cryptographic Apparatus and Method.” US Pate
nt 4,200,770. April 1980.
Rivest, Ronald L. “The MD5 Message-Digest Algorithm”. RFC 1321. April 1992.
Maughan, Douglass, Mark Schetler, Mark Schneider, and Jeff Turner. Internet Security Asso
ciation and Key Management Protocol (ISAKMP). (Internet-draft) draft-ietf-ipsec-isakmp08.
txt, .ps. July 1997.
PART 2
Multicast Routing using Mobile IP
Multicast algorithms classification
Unicast dependent vs. Unicast independent
Source-Based vs. Shared Multicast Tree
[Directly impact on Mobile IP]
Sparse mode vs. Dense mode
Protocols: DVMRP, MOSPF, CBT, PIM(Dense/Sparse)
Unicast dependent vs. Unicast independent
Which one is better ?
Multicast
Unicast
• Use property of specific
unicast routing algorithm
Multicast
Unicast
• Use general unicast function
• Extra Multicast related state
• Deploy limitation
• Better interoperability
• DVMRP(RIP)
MOSPF(OSPF)
• Protocol Independent Multicast
Source-Based vs. Shared Multicast Tree
Source-Based Tree
(DVMRP,MOSPF,PIM_Dense)
Source2 (113.117.238.2)
Source1(128.119.240.5)
A
B
C
Receiver 1
F
D
E
Receiver 2
? How to maintain LEAST UNICAST-COST PATH TREE
• Multicast Open Shortest Path First
• Distance Vector Multicast Routing Protocol
Source-Based vs. Shared Multicast Tree
Forwarding Packet with Source-Based Tree
Reverse Path Forwarding Algorithm
Transmit the packet on all of its
outgoing links only if the packet
arrived on the link that is on its own
shortest path back to the source
Source
A
C
Receiver 1
B
D
Receiver 2
E
Receiver 3
Source-Based vs. Shared Multicast Tree
Shared Tree (Core Base Tree, PIM_Sparse)
Source 1
Source 2
A
B
D (Shared Root)
C
E
Receiver 1
Receiver 2
F
Sparse mode vs. Dense mode
Sparse mode
Pay Per View
Few receiver
Join explicitly
Dense mode
Radio Broadcast
Few non-receiver
Join by default
Broadcast
prune,graft
Shared/Source based tree
Source based tree
CBT, PIM_Sparse
DVMRP, PIM_Dense
Sparse Mode PIM Example
Source
Link
Data
Control
A
B
C
Receiver 1
D
RP
E
Receiver 2
Sparse Mode PIM Example
Receiver 1 Joins Group G
C Creates (*, G) State, Sends
(*, G) Join to the RP
Source
A
B
D
RP
Join
C
Receiver 1
E
Receiver 2
Sparse Mode PIM Example
RP Creates (*, G) State
Source
A
B
C
Receiver 1
D
RP
E
Receiver 2
Sparse Mode PIM Example
Source Sends Data
A Sends Registers to the RP
Source
Register
A
B
C
Receiver 1
D
RP
E
Receiver 2
Sparse Mode PIM Example
RP de-encapsulates Registers
Forwards Data Down the Shared Tree
Sends Joins Towards the Source
Source
Join
A
Join
B
C
Receiver 1
D
RP
E
Receiver 2
Sparse Mode PIM Example
RP Sends Register-Stop
Once
Data Arrives Natively
Source
Register-Stop
A
B
C
Receiver 1
D
RP
E
Receiver 2
Sparse Mode PIM Example
C Sends (S, G) Joins to Join
the
Shortest Path (SPT) Tree
Source
A
B
D
RP
(S, G) Join
C
Receiver 1
E
Receiver 2
Sparse Mode PIM Example
When C Receives Data Natively,
It Sends Prunes Up the RP tree for
the Source. RP Deletes (S, G) OIF and
Sends Prune Towards the Source
Source
(S, G) Prune
A
B
D
RP
(S, G) RP Bit Prune
C
Receiver 1
E
Receiver 2
Sparse Mode PIM Example
New Receiver 2 Joins
E Creates State and Sends (*, G) Join
Source
A
B
D
RP
(*, G) Join
C
Receiver 1
E
Receiver 2
Sparse Mode PIM Example
C Adds Link Towards E to the OIF
List of Both (*, G) and (S, G)
Data from Source Arrives at E
Source
A
B
C
Receiver 1
D
RP
E
Receiver 2
Sparse Mode PIM Example
New Source Starts Sending
D Sends Registers, RP Sends Joins
RP Forwards Data to Receivers
through Shared Tree
Source
Register
A
B
C
Receiver 1
D
RP
E
Receiver 2
Source 2
Dense Mode PIM Example
Source
A
Link
Data
Control
B
G
C
D
F
H
E
Receiver 1
I
Receiver 2
Dense Mode PIM Example
Source
Initial Flood of Data
and Creation of State
A
B
G
C
D
F
H
E
Receiver 1
I
Receiver 2
Dense Mode PIM Example
Source
Prune to Non-RPF Neighbor
A
B
G
Prune
C
D
F
H
E
Receiver 1
I
Receiver 2
Dense Mode PIM Example
Source
C and D Assert to Determine
Forwarder for the LAN, C Wins
A
B
G
C
D
F
Asserts
H
E
Receiver 1
I
Receiver 2
Dense Mode PIM Example
Source
I Gets Pruned
E’s Prune is Ignored
G’s Prune is Overridden
A
Prune
B
G
C
D
F
H
Prune
E
Receiver 1
Join Override
I
Receiver 2
Dense Mode PIM Example
Source
New Receiver, I Sends Graft
A
B
G
C
D
F
H
Graft
E
I
Receiver 1
Receiver 2
Receiver 3
Dense Mode PIM Example
Source
A
B
G
C
D
F
H
E
I
Receiver 1
Receiver 2
Receiver 3
Multicast + Mobile IP
 Mobile Host as Sender
 Using Home Address as packet source address
 Using Care-of Address as packet source address
Mobile Host as Receiver
 Home Subscription
Join multicast group using Home Address
 Remote Subscription
Join multicast group using Care-of Address
Home Address as packet source address
Option 1: Packet directly sent out from foreign network
For Source-Based Tree
(routing related to packet source address)
Packet might not be delivered
For Central Based Tree
(routing uncorrelated to packet source address)
Packet will be delivered correctly
Option 2: Packet tunneled to Home Agent, then sent out
Packet will be delivered correctly
Care-of Address as packet source address
 Packet directly sent out from foreign network
Packet will be delivered correctly
 Problem:
How the misdelivered response reach the
roaming sender ?
Home Subscription
Packet first received at Home Agent, then
forward to the mobile host.
Problem: Tunnel Convergence problem
Source
Home Agent (A)
Home Agent (B)
Foreign Agent
Mobile Host (A)
Mobile Host (B)
Home Subscription
Packet first received at Home Agent, then
forward to the mobile host.
Problem: Tunnel Convergence problem
Source
Home Agent (A)
Designated
Multicast
Service
Provider
Mobile Host (A)
Home Agent (B)
Foreign Agent
Mobile Host (B)
Remote Subscription
 It works fine since multicast packet is
delivered based on multicast group address
 Foreign network router should support multicast
Conclusion
Mobile Host as Sender
 Using Home Address as packet source address
Core Based Tree/ Tunneled packet sent out from Home Agent
 Using Care-of Address as packet source address
Hardly to use
Mobile Host as Receiver
 Home Subscription
Tunnel convergence problem
 Remote Subscription
Foreign network support multicast
References
 Mobile Multicast(MoM) Protocol: Multicast Support for Mobile Hosts. Tim G. Ha
rrison, Carey L. Williason, Wayne L. Mackrell, Richard B. Bunt. U. of Saskatchew
an, Saskatoon, Canadan.Proceedings of the third annual ACM/IEEE international c
onference on Mobile computing and networking. September 26 - 30, 1997, Budape
st Hungary
 RelM: Reliable Multicast for Mobile Networks.Journal of Computer Communicati
ons, 1997.Kevin Brown, Suresh Singh
 Supporting IP Multicast for Mobile Hosts, for review.Yu Wang, Weidong Chen.Sou
thern Methodist University
 Flexible Network Support for Mobile Hosts. X. Zhao, C. Castelluccia, M. Baker. P
roc. MOBICOM '98, Dallas, Texas, 1998, pp. 145--156
 IP Multicast Extensions for Mobile Internetworking. In Proceedings of IEEE Infoc
om'96, March 1996
 IP Multicasting for wireless mobile hosts. George Xylomenos and George C. Poly
zos. Proceedings of the IEEE MILCOM, 10 1996