Mobile IP

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Transcript Mobile IP

IP Mobility
Dr. Eng. Amr T. Abdel-Hamid
Winter 2010
Networks & Services
NETW 903
Mobility and Standard IP Routing
Services & Networks
 IP assumes end hosts are in fixed physical locations
 What happens if we move a host between networks?
 IP addresses enable IP routing algorithms to get packets to the c
orrect network
 Each IP address has network part and host part
This keeps host specific information out of routers
 DHCP is used to get packets to end hosts in networks
This still assumes a fixed end host
 What if a user wants to roam between networks?
Dr. Amr Talaat
 Mobile users don’t want to know that they are moving between netwo
rks
 Why can’t mobile users change IP when running an application?
Netw 903 Lecture 2
Mobility Classification Protocols
Services & Networks
No mobility
mobile wireless user,
using same access
point
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Netw 903 Lecture 2
Moderate mobility
mobile user, connecting/ dis
connecting from network usi
ng DHCP.
High mobility
mobile user, passing through m
ultiple access point while maint
aining ongoing connections (lik
e cell phone)
Mobility Classification Protocols
Services & Networks
Mobility
Global
Macro
Micro
Hierarchical MIP (
1996)
MIP
(1996)
Cellular IP
Hawaii
(1999)
(1998)
TeleMIP
(2000)
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TMIP
Intra-subnet
HMIPv6
(2001)
(2001)
Intra-domain
Netw 903 Lecture 2
Dynamic Mobility Agent
(2000)
MIPv6
(2001)
Inter-domain
Time (evolut
ionary path)
Wirelss access networks and mobile IP
Services & Networks
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Netw 903 Lecture 2
Mobile IP
Services & Networks
 Mobile IP was developed as a means for transparently deali
ng with problems of mobile users
 Enables hosts to stay connected to the Internet regardless of their lo
cation
 Enables hosts to be tracked without needing to change their IP addre
ss
 Requires no changes to software of non-mobile hosts/routers
 Requires addition of some infrastructure
 Has no geographical limitations
 Requires no modifications to IP addresses or IP address format
 Supports security
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 Could be even more important than physically connected routing
Netw 903 Lecture 2
Mobile IP Entities
Services & Networks
 Mobile Node (MN)
 The entity that may change its point of attachment from network
to network in the Internet
 Detects it has moved and registers with “best” FA
 Assigned a permanent IP called its home address to which other
hosts send packets regardless of MN’s location
 Since this IP doesn’t change it can be used by long-lived applicatio
ns as MN’s location changes
 Home Agent (HA)
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



This is router with additional functionality
Located on home network of MN
Does mobility binding of MN’s IP with its COA
Forwards packets to appropriate network when MN is away
 Does this through encapsulation
Netw 903 Lecture 2
Mobile IP Entities contd.
Services & Networks
 Foreign Agent (FA)
 Another router with enhanced functionality
 If MN is away from HA the it uses an FA to send/receive data to/fr
om HA
 Advertises itself periodically
 Forward’s MN’s registration request
 Decapsulates messages for delivery to MN
 Care-of-address (COA)
 Address which identifies MN’s current location
 Sent by FA to HA when MN attaches
 Usually the IP address of the FA
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 Correspondent Node (CN)
 End host to which MN is corresponding (eg. a web server)
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Mobile IP (MIPv4)
Services & Networks
Foreign
Network B
R
Home
network A
Foreign Agent
R
Internet
Home Agent
Network C
R
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Correspondent
Node C
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22.10.20
07
9
Step1:Agent Discovery
Services & Networks
0
M, G bit: Minimal, Gener
ic encapsulation
type = 9
type = 16
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Agent Advertise B bit: Busy
ment
V bit: Van Jacob
Header compression
With TTL=1
Netw 903 Lecture 2
checksum
=9
standard
ICMP fields
router address
length
registration lifetime
Agent Solicitati
on
24
code = 0
=9
H,F bits: home or fore
ign agent
R bit: registration re
quired
16
8
Type=10
sequence #
RBHFMGV
bits
reserved
0 or more care-ofaddresses
| code
mobility agent
advertisement
extension
| checksum
reserved
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10
Step 2: Registration
Services & Networks
Foreign Network B
R

Home Network A

R
Internet
Mobile Node
Foreign Agent
Home Agent
R
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 Foreign agent sends Binding Update
 Home Agent replies with Binding Acknowledgement
Netw 903 Lecture 2
Network C
Correspondent
Node C
Step 2: Registration (Example)
Services & Networks
Mobility binding table at Home Agent
Home address
Care-of address
Lifetime (sec)
128.119.40.186
79.129.13.2
150
…
…
…
Visitor List at Foreign Agent
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Home address
Home agent
address
Media address
Lifetime
128.119.40.186
128.119.40.7
00-56-80-56-A1-E1
150
Netw 903 Lecture 2
Step 2: Registration (Example)
Services & Networks
home agent
HA: 128.119.40.7
foreign agent
COA: 79.129.13.2
visited network: 79.129.13/24
ICMP agent adv.
COA: 79.129.13.2
….
registration req.
COA: 79.129.13.2
HA: 128.119.40.7
MA: 128.119.40.186
Lifetime: 9999
identification: 714
encapsulation format
….
registration req.
COA: 79.129.13.2
HA: 128.119.40.7
MA: 128.119.40.186
Lifetime: 9999
identification:714
….
registration reply
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time
Netw 903 Lecture 2
HA: 128.119.40.7
MA: 128.119.40.186
Lifetime: 4999
Identification: 714
encapsulation format
….
registration reply
HA: 128.119.40.7
MA: 128.119.40.18
6
Lifetime: 4999
Identification: 714
….
Mobile node
MA: 128.119.40.186
Step 2: Registration
Services & Networks
Minimal Encapsulation format
Reg. request format
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Netw 903 Lecture 2
Reg. reply format
Step 3: Indirect Routing via Tunneling
Services & Networks
•Home agent broadcasts ARP request which causes all
nodes in the Home network to update their ARP cache
s to map the mobile nodes IP address to the home age
nts link level address.
packet sent by home agent to foreign a
gent: a packet within a packet (Tunnel)
dest: 79.129.13.2
foreign-agent-to-mobile pack
et
dest: 128.119.40.186
dest: 128.119.40.186
Permanent addres
s: 128.119.40.186
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dest: 128.119.40.186
packet sent by
correspondent
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Care-of address:
79.129.13.2
mobile replies directly
to correspondent
RO(Operation 1: Binding Cache)
Services & Networks
visited
network
home
network
3
2
Binding update
Internet
1
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First Packet to mobile
host
CN
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4
RO (Operation 1: Binding Cache)
Services & Networks
visited
network
Subsequent packets to the mo
bile host
home
network
4
Internet
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CN
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3
5
RO(Operation 2: Smooth handoff)
Services & Networks
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Netw 903 Lecture 2
RO (Operation 2: Smooth handoff)
Services & Networks
foreign network
visited at sessio
n start
Binding
Warning
home
network
Binding U
pdate
FA
3
Internet
2
4
1
Binding Update
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5
New FA
CN
Netw 903 Lecture 2
New
Foreign network
RO (Operation 3: Establishing Registration
keys)
Services & Networks
 If the FA and Mobile node share a security association, the FA can cho
ose the new registration key
 If the HA and the FA share a security association, the HA can choose th
e new registration key
 If the FA has a Public key, the HA can supply a new registration key
 If the Mobile node includes its’ Public key in the registration request, the
FA can choose the new registration key
 The Mobile node and its’ FA can execute a D-H key exchange protocol t
o get a new registration key
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Netw 903 Lecture 2
20
RO(Operation 4: Special Tunnels)
Services & Networks
No visitor list
or Binding cac
he
Special T
unnel
home
network
same
FA1 rebooted
[(FA1, MH), (CN, MH),…
]
5
2
Internet
3
4
Binding Update
1
[(CN,FA1), (CN, MH),…
]
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FA2
CN
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New
Foreign network
Ingress Filtering
Services & Networks
Correspondent, home agent on
same network. Packet from mobile
host is deemed "topologically incorrect"
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correspondent host
home agent
• Routers which see packets coming from a direction from which they would
not have routed the source address are dropped (external domain)
Netw 903 Lecture 2
Reverse Tunneling
Services & Networks
CN
HA
Home
Network
Internet
COA
MH cannot make a
tunnel directly to C
N
FA
MH
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Pro: Firewall and Ingress Filtering problems removed
Con: Lengthy Routing Path (double triangular), increase
in congestion
Netw 903 Lecture 2
Route Optimization Messages
Services & Networks
Binding Acknowledgemen
t
Binding update
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Binding warning
Binding request
Netw 903 Lecture 2
Problems with MIPv4
Services & Networks
 Authentication with FA is difficult as it belongs to another organization
 Guaranteeing QoS to a flow of packets is difficult because of triangulatio
n and tunneling.
 Triangular routing and frequent handoffs cause significant end-to-end de
lay (Micro-mobility helps a bit)
 High signaling load on HA if mobile node moves frequently.
 To support Global mobility, all routers should have FA and HA functional
ity (solved with a reduced scope in Macro-mobility).
 For some applications, it may be important to track the location of mobile
nodes : causes huge power and signaling load.
 Paging (the maintenance of information when the node is idle) is not sup
ported by MIP. (Paging is a procedure that allows a wireless system to search for
Dr. Amr Talaat
an idle mobile host when there is a message destined to it, such that the mobile use
r does not need to register its precise location to the system whenever it moves)
 User perceptions of Internet reliability.
 If FQDN of the Mobile node has many IP addresses, which one to choos
e?
Netw 903 Lecture 2
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25
Hierarchical Mobile IP (HMIP)
Services & Networks
[email protected]
HA
Localizing Registration
s
Internet
[email protected]
[email protected]
FA1
[email protected]
[email protected]
FA2 [email protected]
Lineage <FA4, FA2, FA1>
[email protected]
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FA5
FA3
FA6
[email protected]
<FA6, FA3, FA1>
FA4
Netw 903 Lecture 2
<FA5 FA2, FA1>
Common ancesto
r = FA2 (nearest)
Common ancesto
r = FA1 (nearest)
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26
Mobility using Session Initiation Protocol (
SIP)
Services & Networks
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 A Signaling Protocol
 Originally used for negotiating media sessions be
tween end systems
 Media may go through different networks
 Other uses: Conferencing, VoIP, Instant Messagi
ng etc.
 Elements (SIP user agent, Servers, and Gateway
s)
 Addressing (URLs) e.g. [email protected] and sup
ports both Internet and PSTN address
Netw 903 Lecture 2
SIP Session Setup Example
Services & Networks
SIP
User Agent
Client
INVITE sip:[email protected]
SIP
User Agent
Server
200 OK
ACK
Media Stream
BYE
200 OK
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host.wcom.com
Netw 903 Lecture 2
sip.uunet.com
SIP Proxy Server Example
Services & Networks
SIP
User Agent
Client
SIP
Proxy
Server
INVITE sip:[email protected]
SIP
User Agent
Server
INVITE sip:[email protected]
200 OK
200 OK
ACK
Media Stream
BYE
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200 OK
host.aol.com
Netw 903 Lecture 2
server.aol.com
sip.uunet.com
SIP Redirect Server Example
Services & Networks
SIP
User Agent
Client
SIP
User Agent
Server
SIP
Redirect
Server
REGISTER [email protected]
200 OK
INVITE sip:[email protected]
302 Moved sip:[email protected]
ACK
INVITE sip:[email protected]
180 Ringing
200 OK
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ACK
Media Stream
host.aol.com
Netw 903 Lecture 2
server.aol.com
Mobility using SIP
Services & Networks
4
Mobile
Host
SIP Proxy
Server
Foreign Netwo
rk
1 INVITE
SIP Redirect
Server
5
7
1
2
Home
Network
3
6
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2 302 moved temporarily Corresponding
Host
3, 4 INVITE
5, 6 OK
7 Data
Netw 903 Lecture 2
Benefits: Global mobility, No tunneling, No change to routing
Cellular IP
Services & Networks
Internet
 Cellular IP represents a new mobil
e host protocol
 simple, and flexible protocol for hig
hly mobile hosts
Mobile IP
 CIP supports local mobility & effici
ently internet works with Mobile IP
data/control
packets
•A gateway (GW) acts as foreign agent for ea from MN 1
ch domain (all MNs use GW address as COA)
• Within the domain: host-based routing
• routing cache entries using soft-state
• routing cache updated by upstream pa
ckets
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• separate paging cache for in-active nod
es
 routers within domain have to be CIP awa
re
Netw 903 Lecture 2
BS
MN1
CIP Gateway
BS
BS
packets from
MN2 to MN 1
MN2
Wireless Access network Model
Services & Networks
E
Internet with
Mobile IP
C
D
Gateway A
R
F
B
R
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Beacon signal
Home agent of MH
Netw 903 Lecture 2
G
MH
Packets will be first routed to the host's home
agent and then tunneled to
the gateway
Services & Networks
Packets transmitted by mobile hosts
are first routed to the gateway and
from there on to the Internet
MOBILE IP
The gateway "detunnels'' packets and
forwards them toward base stations
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CELLULAR IP
Netw 903 Lecture 2
Cellular IP Paging
Services & Networks
 Idle mobile hosts that receive a packet move from idle to
active state, start their active-state-timer and immediately
transmit a route-update packet.
 This ensures that routing cache mappings are establishe
d quickly
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Netw 903 Lecture 2
Mobile host state machine
Services & Networks
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Netw 903 Lecture 2
Services & Networks
Efficient Location Management
PAGING &
ROUTING
PC
1
RC
2
3
4
Mobile Host
X
X
X
Service Area
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Two parallel structures of mappings (PC &RC)
1 - idle MH keeps PC upto-date
2 - PC mappings used to find the loc of idle MH
3 - maintains RC mappings until actively connected
4 - routing of data packets to MH
Netw 903 Lecture 2
Services & Networks
Illustration of Paging
I don’t
have a PC
X : from C
X : from G
E
Internet with
Mobile IP
GW
R
G
Paging-update
C
D
A
B
X
MH
F
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Paging-update packets create mappings in PCs
Netw 903 Lecture 2
PCs updated for a moving host
Services & Networks
No change
in PC at A
X : from F
X : from C
X : from G
E
Internet with
Mobile IP
GW
R
X : from F,G
G
G times out
C
D
A
B
X
F
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MH
Netw 903 Lecture 2
Paging packets are routed to the mobil
e host by PCs
Services & Networks
X : from C
X : from F
E
Internet with
Mobile IP
GW
R
G
C
D
A
B
X
F
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MHX
Netw 903 Lecture 2
Handoff
Services & Networks
X : from D
X : from C
X : from D, E
X : from E
X : from F
E
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Internet with
Mobile IP
GW
R
Netw 903 Lecture 2
G
C
D
A
B
F
X
Paging & Routing caches
Services & Networks
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Netw 903 Lecture 2
Handoff
Services & Networks
 Cellular IP handoff
 Hard handoff
 Semi-soft handoff
 Hard handoff
 During the Handoff Latency the downlink packets are l
ost.
 Semi-soft handoff
 Improvement over Hard Handoff
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Netw 903 Lecture 2
Hard-Handoff
Services & Networks
1.MN From Old BS to
New BS
2.MN send Route
Update Packet to G
W
3.BSs are refresh RS
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4.GW send data packet
to MN
Netw 903 Lecture 2
Semi soft-Handoff
Services & Networks
 Improvement over Hard Handoff ; NO packet loss & smo
oth handoff.
 Need for buffering at the cross over point :For smooth ha
ndoff
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Netw 903 Lecture 2
Compare Mobile IP & Cellular IP
Services & Networks
 Location management
 Mobile IP: Care-of-address
 Cellular IP: paging update packet
 Routing
 Mobile IP: registration
 Cellular IP: routing cache
 Handoff
 Mobile IP: encapsulation, triangle routing
 Cellular IP: routing cache
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Netw 903 Lecture 2
Location Management
Services & Networks
 IP-Multicast
 Membership location
 Done thru IGMP & routing
 Meet through the multicast tr
ee
 Mobile-IP
 Mobile node location
 Done thru home agent
 Meet thru registration of n
ew address
Packet Forwarding
• IP-Multicast
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– Multicast forwarding
– Tunnel through the multicast tr
ee (e.g., RP)
Netw 903 Lecture 2
• Mobile-IP
– Unicast forwarding
– Tunnel through home agent
Multicast for Mobility?
Services & Networks
 Instead of obtaining a new COA and registering with the new f
oreign agent (and subsequently with the home agent) and de-r
egistering the old address
 Use the same logical multicast group address and join/leave th
e group as you move
Potential Advantages
• Avoiding ‘triangle routing’ problem
• Avoiding the need for home/foreign agents to continuously
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tunnel packets to the MN
• Smooth hand-off using standard join/prune
• Using shortest path (source-specific trees)
Netw 903 Lecture 2
Multicast-based Mobility (M&M): Archit
ectural Concept
Services & Networks
CN
CN
CN
CN
(b)
(c)
(d)
Wireless link
Mobile Node
(a)
(a) All locations visited by the mobile are part of the distribution tree (at some
point)
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(b) When a mobile moves to a certain location, only that location becomes p
art of the tree (shown by bold lines)
- When the mobile moves to a new location, as in (c) and (d) the distribution
tree changes to deliver packets to the new location.
Netw 903 Lecture 2
Multicast-based Mobility (M&M): Archit
ectural Concept
Services & Networks
Distribution tree dynamics while roaming
CN
CN: Correspondent node (sender
Wireless link
Mobile Node
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Netw 903 Lecture 2
Join/Prune dynamics to modify distribution
Services & Networks
CN
CN: Correspondent node (sender)
Wireless link
Mobile Node
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Netw 903 Lecture 2
Smooth Hand-off
Services & Networks
BS1
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Netw 903 Lecture 2
BS2
Obtaining MN’s multicast address
Services & Networks
 A corresponding node (CN) obtains the multicast address of th
e MN through:
 DNS lookup
similar to getting the unicast (home) address of the
MN
requires update of DNS after allocation of multicast
addresses to MNs
 Startup phase
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CN sends packets to home address
Home agent encapsulates packets in multicast pac
kets sent to the MN
MN decapsulates these packets and sends a bindi
ng update to the CN with its multicast address
Netw 903 Lecture 2