Mobile IP, or TCP/IP on tour Distribuerade system, VT2000 [email protected] Outline Why Mobility? IP routing, very short The need for Mobile IP. Mobile IP - Overview The Gory Details Tunneling Future:
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Transcript Mobile IP, or TCP/IP on tour Distribuerade system, VT2000 [email protected] Outline Why Mobility? IP routing, very short The need for Mobile IP. Mobile IP - Overview The Gory Details Tunneling Future:
Mobile IP, or TCP/IP on tour
Distribuerade
system, VT2000
[email protected]
1
Outline
Why Mobility?
IP routing, very short
The need for Mobile
IP.
Mobile IP - Overview
The Gory Details
Tunneling
Future: Mobility for
IPV6
Open Issues
TCP performance
(RSVP and Real-Time
Traffic)
Service Location
Summary and future
for Mobile IP
2
Mobile IP: A standard for mobile
computing and networking
Computers doesn’t
stay put.
Change location
without restart its
application or
terminating any
ongoing
communication
Example 1: Un-plug
at campus, and plug
it back at home
Example 2: Un-plug
from office, let the
wireless network take
over
3
IP Networking
Protocol layer
Network Layer
Transport Layer
What does IP do
moving packets from
source to destination
No ’end-to-end’
guarantees
IP addresses
Network-prefix
Host portion
IP Routing
Packet Header
Network-prefix
Every node on the
same link has the
same network-prefix
4
The Need for Mobile IP
Fig 3.1
host Specific Routes (too costly)
Node’s IP address (TCP fails)
Link layer (Too many standards)
5
Mobile IP Solves the following
problems
If a node moves from
one link to another
without chnging its IP
address, it will be
unable to receive
packets at the new
link; and
If a node changes its
IP address when it
moves, it will have to
terminate and restart
any on-going
communications each
time it moves
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Mobile IP Overview
Proposed as a
Standard in
November 1996
Solution for Internet
Scalable, robust,
secure, maintain
communication
Use their permanent
IP address
Routing protocol
Route packets to
nodes that could
potentially change
location very rapidly
Layer 4-7, outside
Mobile IP, but will be
of major interest
(TCP, for example)
7
Reqiurements for Mobile IP; A
node must be able to
Communicate wtih
other nodes after
changing its linkLayer attachment to
the internet.
Communicate using
only its home IP
address.
Communicate with
other computers not
using Mobile IP.
Handle security
threats efficiently
8
Design goals
Size and and the frequency as small as possible
Simple to implement.
Aviod solutions that uses multilpe IP adresses
(Running out of IPv4 adresses
9
4.7: Mobile IP Entities and
Relationships (Fig. 4-1)
Mobile Node (mobilen)
Home Agent (Hemagent)
Foreign agent (fjärragent)
Home link (hemmalänk)
Foreign Link (fjärrlänk)
care-of-addresses (c/o, besöksadress)
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Home agent
A router with an interface on the mobile node’
home link
Node keep the Home agent informed of its current
location (care-of-addresses)
Advertises reachability to the network-prefix of the
mobile node’s home adress (Attracting IP adresses)
intercepts packets destined to the mobile node’s home
adress and tunnels them to (c/o)
11
Foreign Agent
A router on a mobile node’s foreign link
which
assists the mobile node in informaing its
home agent of its current (c/o)
provides (c/o) adress and de-tunnels packets
(sent from the home agent)
default router generated by the mobile node.
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Tunneling
An encapsulating IP packet including a path
and an original IP packet
Figure 4-2
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Definitions on ’Home’
Home Adress - IP adress permanently assigned
to a mobile node (Does not change)
Home Link - network-prefix of the mobile node’s
home address define its home link
Home agent - A router that has at least one
interface on the mbile node’s home link
14
Definitions on c/o
A c/o is specific to the foreign link currently being
visited by a mobile node.
A node’s c/o changes every time the mobile node
moves from one foreign link to another
Packets desitnated to a c/o can be delivered using
existing Internet routing mechanisms
A c/o is used as an exit pont of a tunnel from the
home agent toward the mobile node
15
4.8: A high Level desription
(Fig. 4-3)
Home agents and foreign agents advertise their
presence by periodically multicasting (broadcasting)
Agent advertisements
Mobile node’s listens to Agent advertisements (I am
a home or away)
A mobile node connected to a foreign link acquires
a c/o adress
Mobile node registers its c/o address with its home
agent
16
4.8: A high Level desription
(Fig. 4-3) Cont:
Home agent adverties reachibility to the netwrokprefix of the mobile node’s home link (Attracting
packets sent to the mobiles home adress.
Intercept these messages and tunnels them to the C/O
At C/O, the original packet is extracted from the
tunnel and then delivered to the mobile node
In reverse odirection, packets sent from the mobile
node are routed directly to thier destination,
without need for tunneling (FA only router)
17
5: The gory details
Agent Discovery
Determines whether it is currently connected to its
home link or a foreign link.
Detects whether it has moved from one link to
another
obtains a care-of adress when connected to a foreign
link
18
5.2.1: Messages
Agent advertisements; Used by agents to
announce their capabilities to mobile nodes
Agent advertisements are continuously transmitted
(multicast/broadcoast) on a specific link
Allow the mobiles to determine whether any agent is
present (gets identities)
Agent solicitations; are sent by mobile that do
not have the patience to wait for an Agent
advertisment
19
5.2.2 How does a mobile node
detrmine that is has moved?
Using Lifetime: Tells the mobile how soon it
should expect to hear another Agent
Advertisment.
AA three times faster than Lifetime
Multiple foreign agents
20
5.3 What is registration
A mobile node
register whenever it detects that it has chnged link from
one network to another.
Reregisters when it has not moved, but when it existing
registration due to expire.
Mobile IP registration is the process by which a mobile node:
requests routing services from a foreign agent or foreign
link
informs its home agent of its current care-of-address.
Renews a registration due to expire
deregisters when it returns to its home link
21
5.3.1 Registration scenarios
A registration consists of an exchange of a
Registration request and a Registration Reply
between a mobile node and its home agent.
Three common scenarios:
Using foreign agent c/o
Using collocated c/o
deregisters upon returning home
22
5.3.2 How do nodes Process
registrations
Se summary
23
5.3.3 How can a Mobile learn
24
5.3.4. How Does
25
5.4: How are the Packets
routed
26
5.4.6 Why the triangle routing
27
5.5 Summary
Agent Discovery
Registration
Routing
28
Tunneling: 6.1 IP
Encapsulation
29
Future Topics;
12: IPv6 vs IPv4
Work in progress
Size adresses: 128 bits vs 32 bits
No real chance of running out of adresses
A single newtowrk-prefix route
Autoconfigure using very simple mechanisms
Less frequently used fields in IPv4 moved
into optional
IPv6 more rigorously defined (more useful)
30
12.2 Relevant to Mobile IP V6
Larger adresses - No need for Foreign agents
Collocated C/O is the only one needed, snice there are
sufficient IP adresses
New routing Header help
Security attack (less options)
Very fast forward desicion- not all routers need to read
by every router, Router Discovery
Static Address Autoconfiguration -
31
12.1.1 Headers
Base: Priority fields, Flow label (Real-time traffic)
Extension headers: Form a chain of headers
32
12.4 How Does it work
33
12.5 How does a Mobile ...
34
12.6 How Does
35
12.8: IP V6 summary
36
13: Open Issues. 13.1: TCP
Performance and Mobility
37
13.1.1: What is TCP
38
13.1.2: How does TCP works
39
13.1.3: Are TCP’s ..
40
13.1.4: How can TCP
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13.2 RSVP and Real-Time
Traffic
42
13.3 Service Location
43
14: Summary
Background
Terminology
Applying Mobile IP
Open Issues
44
14: The future of Mobile IP
45