Mobile IP Add it into TCP/IP implementation Wireless communication techniques Wireless technique...
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Transcript of Mobile IP Add it into TCP/IP implementation Wireless communication techniques Wireless technique...
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
802.16 (WMAN)
50 km for fixed station
5-15 km for mobile one
30 Mbps-
75 Mbps?
2-66 GHz
2-11 GHz?
3G (W-CDMA, TD-SCDMA,...)
384 Kbps-14 Mbps
OFDM-MIMO
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
Wireless net Wireless net
CELL CELL R—router H—stationary hosts AP—Access Point MH—mobile host RSR—Roam Supervisor Router
Internet
RHH
RSRAP
MH MH
R Network
R H
AP
MH MH
RSR
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
• 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 int
ercept and tunnel datagrams to MH. • foreign agent :
Concepts:
I nternet ①
移动 HA—Home Agent A-- 移动主机 R— Router H—固定主机
移动 I Pv4的工作原理示例
B
HA H
R A
FA H
AP
A
Internet ①
move
HA—home agent A—mobi l e host R— router H—fixed host
Principle of mobi le IPv6
B
HAH
RA
R H
AP
A
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:
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
FA
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 :
In practice, there are two types of care-of addresses• foreign agent care of address IPv4• co-located care-of address IPv6
Care-of address
• 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.
Internet ① 移动
B
HA H
R A
FA H
AP
A
6. Datagram transmission and reception--- for 4)
IPA IPB
Send
?
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.
IPB
shortest path
1) MH sends datagram
⑥ Internet ①
移动
B
HAH
RA
FA H
AP
A
IPB IPA
IPB IPA IPHA IPFA
IPB IPA
Receive
• Datagram will travel to the mobile’s home network. • HA intercepts the datagram and uses IP-in-IP encap
sulation to tunnel the datagram to the care-of address
• FA decapsulates the datagram and transmit the datagram to the mobile.
FAHA
2) MH receives datagram