Mobile Networking through Mobile IP

Presenter: Guimin Zhang

Truly Mobile Networking

Provide confident access to the Internet anytime, anywhere

Reconnection occurs automatically and noninteractively

Mobility transparent to applications and higher level protocols such as TCP

Today’s Internet Protocol

Packets are routed to destinations based on IP address

128.143.71.50 128.143.77.83

router 71 gilmer

garrett

IP Network

Apply to Mobile Networking

128.143.71.50 128.143.77.84

IP Network

Apply to Mobile Networking

128.143.71.50

IP Network

128.143.77.84

X

Mobile IP Approach

Mobile IP uses two IP addresses:

Home address: The IP address assigned to the

mobile node, making it logically appear attached to its home network.

Care-of address: An IP address at the mobile node's

current point of attachment to the Internet, when the mobile node is not attached to the home network.

Mobile Network Terminology (1)

Home network: The network at which the mobile node

seems reachable, to the rest of the Internet, by virtue of its assigned IP address.

Foreign network: The network to which the mobile

node is attached when it is not attached to its home network, and on which the care-of address is reachable from the rest of the Internet.

Mobile Network Terminology (2)

Home agent: A router on the home network that

effectively causes the mobile node to be reachable at its

home address even when the mobile node is not attached

to its home network.

Foreign agent: A router on the foreign network that

can assist the mobile node in receiving datagrams

delivered to the care-of address.

How Mobile IP Works

128.143.71.50

router 71router 77

virginia.net

IP Network

128.143.77.84

HA

128.143.71.50

router 71router 77

virginia.net

IP Network

How Mobile IP Works

128.143.77.84

HA

FA

Register

Discovery

Discovering the care-of address Registering the care-of address Tunneling to the care-of address

Agent Discovery Protocol

Extends ICMP Router Discovery protocol

ICMP Router Discovery Protocol enables hosts attached to multicast or broadcast networks to discover the IP

addresses of their neighboring routers. Agent advertisements: The mobile agent

broadcast agent advertisements at regular intervals. Agent solicitation: The mobile node broadcast or

multicast a solicitation that will be answered by any foreign agent or home agent that receives it.

Advertisement Message Formats ICMP Router Advertisement Agent Advertisement extension

Type: 16 R: register required B: busy H: home agent F: foreign agent M: minimum encapsulation G: GRE encapsulation V: Van Jacobson header compression

Advertisement Message Formats ICMP Router Advertisement Prefix Length extension

Type: 19 Prefix Length:network number of

the corresponding Router Address listed in the ICMP Router Advertisement portion of the message.

Mobile Node Move Detection

Lifetime basedThe mobile node record the Lifetime of advertisement message. If it fails to receive another advertisement from the same agent until the the Lifetime expires, it considers to find a new agent.

Network prefixes basedThe Prefix-length extension is used to determine if the newly received advertisement is in the same subnet as the mobile node’s current care-of-address.

Registration

MH: mobile host; FA: Foreign Agent; HA: Home Address

Exchange of Registration Request and Registration Reply messages: UDP using well-known port 434

Foreign Agent Consideration

Each foreign agent must be configured with a care of address

For each pending or current registration, the foreign agent maintains a visitor list entry containing: Link-layer source address of the mobile node The mobile node’s Home Address The Home Agent address The identification field The requested registration Lifetime The remaining Lifetime of the pending or current registration

Security Considerations in Registration

Danger: Registration Request works remotely to the

home agent to affect the home agent's routing table Security:

Authentication: Home agents and mobile nodes perform authentication using MD5 algorithm and key size of 128 bits.

Replay Protection: The Identification field is used to verify that a registration message has been freshly generated.

timestamp , random number

Tunneling to the Care of Address

Changes with IP Version 6

Route Optimization When it knows the mobile node's current care-of

address, a correspondent node can deliver packets directly to the mobile node's home address without any assistance from the home agent

Security Strong authentication and encryption features are

included in IP V6

Problems Facing Mobile IP

Security issues Routing inefficiency

Triangle routing Ingress filtering User perceptions of reliability Competition from other protocols

Mobile IP Related Projects

The CMU Monarch Project: Protocols for Adaptive Mobile and Wireless Networking

Portland State Secure Mobile Networking Project

State University of New York, Binghamton's Linux-Mobile IP

Stanford's Operating Systems and Networking Group's MosquitoNet

BBN Technologies' Mobile IP Security page

Reference

"Mobile Networking through Mobile IP," C. Perkins, IEEE Internet Computing, Vol. 2, No. 1, 1998.

"Mobile IP ,"  C. Perkins, IEEE Communications Magazine, Vol. 35, No. 5, 1997.