Mobile%20IP

1
Mobile IP

• Performance Issues in Practice

2
Introduction

• What is Mobile IP?
• Mobile IP is a technology that allows a "mobile
  node" (MN) to change its point of attachment to
  the Internet while communicating with the
  "correspondent node" (CN) using IP.
• Portable IP verses Mobile IP Laptop verses
  Mobile Phone

3
Key Issues

• Why need Mobile IP?
• Implementation of Mobile IP
• Mobile IPv4
• IP Routing
• IP QoS

4
So, why Mobile IP?

• In original IP routing, mobility of hosts was not
  considered to be an issue.
• Routing methods built for static networks
• Hosts were unlikely to move from one subnet to
  another.
• Mobile IP defines protocols and procedures by
  which packets can be routed to a mobile node,
  regardless of its current point-of-attachment to
  the Internet, and without changing its IP
  address.

5
Mobility Vocabulary
visited network network in which mobile
currently resides (e.g., 79.129.13/24)
Permanent address remains constant (e.g.,
128.119.40.186)
Care-of-address address in visited
network. (e.g., 79.129.13.2)
wide area network
foreign agent entity in visited network that
performs mobility functions on behalf of mobile
agent.
correspondent hosts wants to communicate with
mobile device
6
Mobility via Indirect Routing
visited network
home network
wide area network
7
Packet Formation
Data sent by a node to a Mobile IP
HA IP
Header with Mobile IP
Header
Data
New Data Packet from Home Agent to MN
8
Mobile IP v4 Registration Request Header
9
Mobile IP v4 Registration Reply Header
10
Mobile IP v4 UDP Packet Header
11
IP Routing

• Two most popular protocols
• Distance Vector Protocol
• Link State Protocol

12
Distance Vector Protocol

• In DVP, each node contains a routing table with a
  list of shortest paths to the other nodes in the
  network
• At start, each node has knowledge of its own
  address and is able to transmit on all links
  connecting to neighboring nodes
• If distance to the node is shorter than the
  distance in the routing table, the distance table
  is updated with the new value
• When transmission of distance vector no longer
  causes an update of the tables, the protocol
  converges and the topology of the network has
  been fixed

13
Link State Routing Protocols

• All nodes maintain a distributed map of the
  network
• Maps are updated quickly, when network topology
  changes using.??
• LSP use Shortest Path First algorithm (Dijkstras
  Algorithm)
• Considered better than Distance Vector Protocols.
  Why ??

14
Why these protocols Fail in Mobile IP

• Cellular Systems and Internet networks supporting
  mobile users depend on a fixed infrastructure
• Base station can always reach all mobile nodes in
  the cell without routing, via a broadcast
• But, Mobile Networks have a special case of
  Ad-Hoc Networks

15
Routing in Ad-Hoc Networks

• In Ad-hoc networks,
• A fixed infrastructure is missing and topologies
  change quickly
• A destination node might be out of range of a
  source node transmitting packets
• Each node must be able to forward data to other
  nodes

16
So why do they fail in Ad-Hoc networks

• Dynamic routing algorithms assume network
  topology does not change during transmission
• they would react too slowly or generate too much
  traffic to update the tables their updating
  frequency of about 30 sec is too long for ad-hoc
  networks
• Routing algorithms depend on symmetric links in
  which routing information colleted for one
  direction can be used for other direction in
  ad-hoc networks, links can be asymmetric
• Interference amongst close nodes that
  simultaneously forward transmissions

17
QoS Issues

• Most popular techniques
• IntServ and RSVP
• DiffServ
• MPLS
• IntServ maintains per-flow states in each node
• DiffServ approach discriminates amongst datagrams
  in different classes, not flows
• MPLS forces traffic into specific labeled
  switched paths (LSPs) using routers called as
  labeled-switching routers (LSRs)

18
Performance considerations

• The RSVP method does not fit into Mobile IP QoS
  architecture

Resv
S
R1
R2
R3
R
Path
RSVP Operation
19
Failure of RSVP

• Processing overheads and memory consumption
  directly proportional to the number of separate
  RSVP reservations
• Also, states reservation is not possible over the
  tunnel between Home Agent and Foreign Agent why
  ??

20
Solution RSVP over IP Tunnels

• This mechanism enables reservations across all
  IP-within-IP tunnels
• The tunnels are of three types
• Type 1 no QoS guarantees (best effort tunnel)
• Type 2 no resource allocation to individual data
  flows, but QoS guarantees to aggregate flows
• Type 3 resource allocation for individual end to
  end flows

21
RSVP over IP Tunnels (contd)
M3
M1
R1
Intermediate Router
Intermediate Router
R2
M2
IP TUNNEL
M4
22
Mobility Management in Real Time Services

• Makes use of the mobility notification method
• Working
• sender delivers a PATH message to MN
• When mobile node not connected to HN, HN captures
  the RSVP message and replies to sender with a
  PathChange message containing the COA of MN and
  its own address (MOBILITY_NOTIFICATION Object)
• Source receives PathChange message, caches it and
  sends new PATH message to mobile node, tunneling
  it to COA