Mobile IP

Description Glossary RFCs Publications Obsolete RFCs


Protocol suite: TCP/IP.
Protocol type:Application layer protocol.
Port:434 (UDP) control.
MIME subtype:
Working groups: mip4, Mobility for IPv4.
mobileip, IP Routing for Wireless/Mobile Hosts.
Links: IANA: Mobile IP numbers.
wiki: Mobile IP.

RFC 3344:

Agent Discovery is the method by which a mobile node determines whether it is currently connected to its home network or to a foreign network, and by which a mobile node can detect when it has moved from one network to another. When connected to a foreign network, the methods specified in this section also allow the mobile node to determine the foreign agent care-of address being offered by each foreign agent on that network.

Mobile IP extends ICMP Router Discovery as its primary mechanism for Agent Discovery. An Agent Advertisement is formed by including a Mobility Agent Advertisement Extension in an ICMP Router Advertisement message. An Agent Solicitation message is identical to an ICMP Router Solicitation, except that the IP TTL MUST be set to 1.

MAC header IP header UDP header Mobile IP header Data :::

Mobile IP header:

0001020304050607 0809101112131415 1617181920212223 2425262728293031
Type Data :::

Type. 8 bits.

0 One byte padding. RFC 3344
1 Registration request. 
3 Registration reply. 
4 MIP Tunnel Data Message. RFC 3519
7 Registration Revocation. RFC 3543
15 Revocation Acknowledgment. RFC 3543
16 Mobility Agent Advertisement. RFC 3344, RFC 4881
17 Handoff Reply.RFC 4881
18 Regional Registration request. RFC 4857
19 Regional Registration reply. RFC 3344, RFC 4857
20 FBU, Fast Binding Update.RFC 4988
21 FBAck, Fast Binding Acknowledgment.RFC 4988
24 Challenge Extension. RFC 3012
32 Mobile-Home authentication. RFC 3344
33 Mobile-Foreign authentication. RFC 3344
34 Foreign-Home authentication. RFC 3344
36 Generalized Mobile IP Authentication. RFC 3012
38 CVSE, Critical Vendor/Organization Specific Extension. RFC 3115
40 MN-FA-KeyGen Request. RFC 3957
41 MN-FA-KeyGen Reply. RFC 3957
42 MN-HA-KeyGen Request. RFC 3957
43 MN-HA-KeyGen Reply. RFC 3957
446UDP Tunnel Reply Extension. RFC 3519
45 FA Error Extension.RFC 4636
46 GFA IP Address Extension.RFC 4857
47 PMIPv4 Non-skippable Extension. 
127 Non-skippable extension for experimental use. RFC 4064
128 (deprecated, 2001 Aug 31). 
129 SKIP Firewall Traversal Extension. RFC 2356
130 Encapsulating Delivery Style Extension. RFC 3024
131 Mobile Node NAI. RFC 2794
132 MN-FA Challenge Extension.RFC 4721
134 NVSE, Normal Vendor/Organization Specific Extension. RFC 3115
136 NAI Carrying Extension. RFC 3846
1371+Revocation Support. RFC 3543
138 Generalized Link Layer Address Registration ExtensionRFC 4881
139 Dynamic HA Extension.RFC 4433
140 Hierarchical Foreign Agent Extension.RFC 4857
141 Replay Protection Style.RFC 4857
142 Regional Registration Lifetime Extension.RFC 4857
1446UDP Tunnel Request Extension. RFC 3519
145 Message String Extension.RFC 4917
147 PMIPv4 Skippable Extension. 
148 Mobile Network Extension. RFC 5177
149 Trusted Networks Configured (TNC) Extension. 
150 reserved. 
151 Service Selection Extension. 
255 Skippable extension for experimental use. RFC 4064


Agent Advertisement.
(RFC 3220) An advertisement message constructed by attaching a special extension to a router advertisement message.

(RFC 3344) The process of verifying (using cryptographic techniques, for all applications in this specification) the identity of the originator of a message.

Authorization-enabling extension.
(RFC 3220) An authentication which makes a (registration) message acceptable to the ultimate recipient of the registration message. An authorization-enabling extension MUST contain an SPI.

Care-of Address.
(RFC 3220) The termination point of a tunnel toward a mobile node, for datagrams forwarded to the mobile node while it is away from home. The protocol can use two different types of care-of address: a "foreign agent care-of address" is an address of a foreign agent with which the mobile node is registered, and a "co-located care-of address" is an externally obtained local address which the mobile node has associated with one of its own network interfaces.

Correspondent Node.
(RFC 3220) A peer with which a mobile node is communicating. A correspondent node may be either mobile or stationary.

Foreign Agent.
(RFC 3220) A router on a mobile node's visited network which provides routing services to the mobile node while registered. The foreign agent detunnels and delivers datagrams to the mobile node that were tunneled by the mobile node's home agent. For datagrams sent by a mobile node, the foreign agent may serve as a default router for registered mobile nodes.

Foreign Network.
(RFC 3220) Any network other than the mobile node's Home Network.

Forward Tunnel.
(RFC 3024) A tunnel that shuttles packets towards the mobile node. It starts at the home agent, and ends at the mobile node's care-of address.

Gratuitous ARP.
(RFC 3344) An ARP packet sent by a node in order to spontaneously cause other nodes to update an entry in their ARP cache.

Home Address.
(RFC 3220) An IP address that is assigned for an extended period of time to a mobile node. It remains unchanged regardless of where the node is attached to the Internet.

Home Agent.
(RFC 3220) A router on a mobile node's home network which tunnels datagrams for delivery to the mobile node when it is away from home, and maintains current location information for the mobile node.

Home Network.
(RFC 3220) A network, possibly virtual, having a network prefix matching that of a mobile node's home address. Note that standard IP routing mechanisms will deliver datagrams destined to a mobile node's Home Address to the mobile node's Home Network.

(RFC 3220) A facility or medium over which nodes can communicate at the link layer. A link underlies the network layer.

Link-Layer Address.
(RFC 2002) The address used to identify an endpoint of some communication over a physical link. Typically, the Link-Layer address is an interface's Media Access Control (MAC) address.

MN, Mobile Node.
(RFC 3220) A host or router that changes its point of attachment from one network or subnetwork to another. A mobile node may change its location without changing its IP address; it may continue to communicate with other Internet nodes at any location using its (constant) IP address, assuming link-layer connectivity to a point of attachment is available.

MA, Mobility Agent.
(RFC 2002) Either a home agent or a foreign agent.

Mobility Binding.
(RFC 2002) The association of a home address with a care-of address, along with the remaining lifetime of that association.

Mobility Security Association.
(RFC 2002) A collection of security contexts, between a pair of nodes, which may be applied to Mobile IP protocol messages exchanged between them. Each context indicates an authentication algorithm and mode, a secret (a shared key, or appropriate public/private key pair), and a style of replay protection in use.

(RFC 2002) A host or a router.

(RFC 2002) A randomly chosen value, different from previous choices, inserted in a message to protect against replays.

Reverse tunnel.
(RFC 3024) A tunnel that starts at the mobile node's care-of address and terminates at the home agent.

SPI, Security Parameter Index.
(RFC 2002) An index identifying a security context between a pair of nodes among the contexts available in the Mobility Security Association. SPI values 0 through 255 are reserved and MUST NOT be used in any Mobility Security Association.

(RFC 2002) The path followed by a datagram while it is encapsulated. The model is that, while it is encapsulated, a datagram is routed to a knowledgeable decapsulating agent, which decapsulates the datagram and then correctly delivers it to its ultimate destination.

Virtual network.
(RFC 2002) A network with no physical instantiation beyond a router (with a physical network interface on another network). The router (e.g., a home agent) generally advertises reachability to the virtual network using conventional routing protocols.

Visited network.
(RFC 2002) A network other than a mobile node's Home Network, to which the mobile node is currently connected.

Visitor list.
A list of the mobile nodes visiting a foreign agent.


[RFC 2005] Applicability Statement for IP Mobility Support.

[RFC 2006] The Definitions of Managed Objects for IP Mobility Support using SMIv2.

[RFC 2977] Mobile IP Authentication, Authorization, and Accounting Requirements.

[RFC 3012] Mobile IPv4 Challenge/Response Extensions.

[RFC 3024] Reverse Tunneling for Mobile IP, revised.

[RFC 3115] Mobile IP Vendor/Organization-Specific Extensions.

[RFC 3344] IP Mobility Support for IPv4.

[RFC 3519] Mobile IP Traversal of Network Address Translation (NAT) Devices.

[RFC 3543] Registration Revocation in Mobile IPv4.

[RFC 3583] Requirements of a Quality of Service (QoS) Solution for Mobile IP.

[RFC 3846] Mobile IPv4 Extension for Carrying Network Access Identifiers.

[RFC 3957] Authentication, Authorization, and Accounting (AAA) Registration Keys for Mobile IPv4.

[RFC 4064] Experimental Message, Extensions, and Error Codes for Mobile IPv4.

[RFC 4093] Problem Statement: Mobile IPv4 Traversal of Virtual Private Network (VPN) Gateways.

[RFC 4332] Cisco's Mobile IPv4 Host Configuration Extensions.

[RFC 4433] Mobile IPv4 Dynamic Home Agent (HA) Assignment.


Obsolete RFCs:

[RFC 2002] IP Mobility Support.

[RFC 2344] Reverse Tunneling for Mobile IP.

[RFC 3025] Mobile IP Vendor/Organization-Specific Extensions.

[RFC 3220] IP Mobility Support for IPv4.

Description Glossary RFCs Publications Obsolete RFCs