Transcript Mobile IP

Mobile IP
Add it into TCP/IP implementation
Wireless communication techniques
Wireless
technique
Distance
Transfer
rate
Frequency
Bluetooth
802.15 (WPAN)
10 m
3M bps
2.4 GHz
Wi-Fi (WLAN)
802.11
150 m
54 Mbps
WiMAX
50 km for fixed station
802.16 (WMAN) 5-15 km for mobile one
30 Mbps75 Mbps?
3G (W-CDMA,
384 Kbps14 Mbps
TD-SCDMA,...)
OFDM-MIMO
2-66 GHz
2-11 GHz?
1. Introduction
Discuss IP address and routing for mobile host(MH).
• MH moves from one network to another --->
its IP address and routing change
• MH moves within wireless LAN --->
its IP address and routing don’t change
Changing an address is time-consuming, requires
rebooting computer, and breaks all existing TCP
connections
H
H
R
R
Internet
Network
R
RSR
AP
RSR
AP
Wireless net
Wireless net
MH
MH
MH
MH
CELL
CELL
R—router
H—stationary hosts
MH—mobile host
AP—Access Point
RSR—Roam Supervisor Router
H
2. Mobile IP and some concepts
IETF devised mobile IP, a solution to the mobility
problem.
• Transparency.
Applications always use MH’s home address. All
open TCP connections survive a change in network
• Interoperability with IPv4
MH can interoperate with stationary hosts that run
conventional IPv4 software
Concepts:
• home net.：the network on which MH registers
• foreign net.：
• home address：IP address obtained on home net.
It is permanent and fixed. Applications use it
• care-of address： IP address obtained at foreign
net. It is temporary (variable). IP layer uses it.
• home agent：a router on home net. It agree to
intercept and tunnel datagrams to MH.
• foreign agent：
B
H
HA
FA
H
Internet
①
A
R
AP
移动
A
HA—Home Agent
R— Router
A-- 移动主机
H—固定主机
移动 IPv4 的工作原理示例
B
H
HA
R
H
Internet
①
A
R
AP
move
A
HA—home agent
R— router
A—mobile host
H—fixed host
Principle of mobile IPv6
3. Overview of mobile IP operation
1) MH finds that itself moves to a foreign network
2) MH obtains a care-of address from FA
3) MH(FA) informs HA of its care-of address
4) HA intercepts datagrams sent to the MH’ home
address, and tunnel each datagram to the care-of
address
5) when MH returns home, it contact HA to deregister
The issues to be solved are 1), 2), 4)
4. Foreign agent discovery --- for 1)
MH uses ICMP router discovery mechanism to find
that itself moves to a foreign network. Recall:
• routers periodically send ICMP router
advertisement messages to all nodes on the net.
• a host can send an ICMP router solicitation to
prompt for an advertisement:
FA
1) Foreign agent discovery
MH has a default router.
If MH receives an ICMP router advertisement
message from other router, it know that itself moves
to a foreign network.
To confirm it, MH can send an ICMP router
solicitation message to ?HA and waits for a reply
2) Agent registration
MH send registrations request to FA, which then
contacts HA on its behalf.
Registration message includes:
{ home address, care-of address, HA, …}
FA
5. Obtains a care-of address --- for 2)
Router advertisement message piggybacks
additional information known as a mobility agent
extension which includes care-of addresses :
Care-of address
In practice, there are two types of care-of addresses
• foreign agent care of address
IPv4
• co-located care-of address
IPv6
• Foreign agent care of address is one of FA’ IP
addresses so that MH doesn’t consume IP address.
• Co-located care-of address is a new IP address
allocated to MH by DHCP.
It requires MH to handle all forwarding itself.
6. Datagram transmission and reception--- for 4)
Send
B
H
HA
FA
H
Internet
①
A
R
AP
移动
A
IPA IPB
?
1) MH sends datagram
shortest path
IPB
The mobile creates a datagram that has destination
computer’s address in the destination field and the
mobile’s home address in the source field.
Receive
B
H
HA
FA
⑥
H
Internet
①
A
R
AP
移动
A
IPB IPA
IPB IPA IPHA IPFA
IPB IPA
2) MH receives datagram
HA
FA
• Datagram will travel to the mobile’s home network.
• HA intercepts the datagram and uses IP-in-IP
encapsulation to tunnel the datagram to the care-of
address
• FA decapsulates the datagram and transmit the
datagram to the mobile.