RFC 2005

RFC 2005: Applicability Statement for IP Mobility Support 🦋

okay bestie, RFC 2005 is an Applicability Statement from the Network Working Group 💅 It was written by J. Solomon at Motorola and dated October 1996. Its category is Standards Track ✨ The title block doesn't list anything it obsoletes or updates. That's the whole intro, now let's get into it 🎀

Status of this Memo 💌

this one is an Internet standards track protocol for the Internet community, and it's asking for discussion and suggestions for improvements 🙌 for the standardization state and status, check the current edition of the "Internet Official Protocol Standards" (STD 1) 📚 Distribution of this memo is unlimited. 🌈

Abstract 🧚

okay so, As required by [RFC 1264], this report talks about how Mobile IP applies to giving hosts mobility on the Internet ✨ it breaks down the key features of Mobile IP and shows how the requirements for advancing to Proposed Standard RFC got met 💖

1. Protocol Overview ✨

Mobile IP is giving efficient, scalable node mobility on the Internet 🔥 with it, nodes can change their point-of-attachment to the Internet without changing their IP address, so their transport and higher-layer connections survive the move 🫶 and it does all this without having to propagate host-specific routes through the whole Internet routing fabric 💅 the protocol is documented in [MIP-PROTO].

the routing is kind of iconic 👑 packets for a mobile node get routed first to its home network, which is the network identified by the network prefix of the mobile node's (permanent) home address 🏠 there, the mobile node's home agent grabs those packets and tunnels them to the most recently reported care-of address. at the tunnel's endpoint, the inner packets get decapsulated and delivered to the mobile node 🦋 going the other way, packets sourced by mobile nodes just use standard IP routing to reach their destinations 🌸

so yeah, Mobile IP leans on protocol tunneling to deliver packets to mobile nodes that are away from home 🧚 the home address is hidden from routers between the home agent and the mobile node because of the tunnel 🙈 the outer packet goes to the mobile node's care-of address, which is a topologically significant address, so standard IP routing can actually deliver things there 💜

the Mobile IP protocol defines:

• an authenticated registration procedure where a mobile node tells its home agent(s) its care-of address(es) 📮
• an extension to ICMP Router Discovery [RFC1256] that lets mobile nodes find prospective home agents and foreign agents 🔍 and
• the rules for routing packets to and from mobile nodes, including one mandatory tunneling mechanism ([MIP-IPinIP]) and several optional tunneling mechanisms ([MIP-MINENC] and [RFC1701]) 🍓

2. Applicability 🎯

Mobile IP is meant to solve node mobility across changes in IP subnet 🙌 it's just as suitable for mobility across homogeneous media as across heterogeneous media 💖 so it handles moving from one Ethernet segment to another just as well as moving from an Ethernet segment to a wireless LAN 🌈

think of Mobile IP as handling the "macro" mobility management problem 🗺️ it's less well suited to "micro" mobility management, like handoff between wireless transceivers that each cover a super tiny area 🙈 in that situation, link-layer mechanisms for link maintenance (that's link-layer handoff) might offer faster convergence and less overhead than Mobile IP ⭐

Mobile IP scales to a large number of mobile nodes on the Internet 💅 without route optimization as described in [MIP-OPTIM], though, the home agent is a potential load point when serving lots of mobile nodes 😭 when home agents get overburdened, more home agents can be added, and even dynamically discovered by mobile nodes, using mechanisms defined in the Mobile IP documents 🫶

last bit: mobile nodes get their (home) IP addresses pretty much the same way stationary hosts get long-term IP addresses, meaning the authority that owns them assigns them 👑 when it's applied properly, Mobile IP lets mobile nodes communicate using only their home address no matter where they are 🧚 so Mobile IP doesn't try to fix the problems of local or global IP address renumbering at all 🙅‍♀️

3. Security 🔐

okay this section is serious, bestie 🚨 Mobile IP mandates cryptographically strong authentication for all registration messages exchanged between a mobile node and its home agent 🔥 strong authentication can optionally be used between foreign agents and mobile nodes or home agents too 💜 replay protection comes from one of two possible mechanisms: timestamps or nonces ⏰

because there's no Internet key management protocol available, agent discovery messages are not required to be authenticated 💀

All Mobile IP implementations are required to support, at a minimum, keyed MD5 authentication with manual key distribution. Other authentication and key distribution algorithms may be supported. 🫶

Mobile IP only defines security mechanisms for the registration protocol. Implementations that need privacy and/or authentication of data packets sent to and from a mobile node should use the IP security protocols described in RFCs 1827 and 1826 for this purpose. 🛡️

4. MIB 📊

At the time this Applicability Statement was published, a Management Information Base (MIB) for Mobile IP had been written and documented in RFC 2006 ✨

5. Implementations 🛠️

several implementations of Mobile IP are known to exist 🎉 here's the origin and a contact for several of them:

   Organization:   Contact:

   CMU             Dave Johnson <dbj@cs.cmu.edu>
   FTP Software    Frank Kastenholz <kasten@ftp.com>
   IBM             Charlie Perkins <perk@watson.ibm.com>
   Motorola        Jim Solomon <solomon@comm.mot.com>
   Nokia           Gunyho Gabor <gunyho@ncsmsg07he.ntc.nokia.com>
   SUN             Gabriel Montenegro <gab@cali.Eng.Sun.COM>
   Telxon          Frank Ciotti <frankc@teleng.eng.telxon.com>

6. Implementation Experience 🧪

FTP Software hosted an interim meeting, October 23-27, 1995, where they showed that several implementations could interoperate 🥳 these major features of Mobile IP got tested:

1. Mobile Nodes receiving and processing Agent Advertisements.
2. Agents receiving Agent Solicitations and responding with Agent Advertisements.
3. Mobile Nodes registering with foreign agents on foreign networks.
4. Packets being received by the mobile node after having been tunneled by the home agent and de-tunneled by the foreign agent.
5. Packets from the mobile node being routed directly to their destinations.
6. Mobile nodes discovering that their connectivity/subnet had changed and re-registering at their new location.
7. Mobile nodes discovering that their current foreign agent had rebooted and therefore re-registering with that foreign agent.
8. The required form of tunneling (IP-in-IP encapsulation [MIP-IPinIP]) as well as the one of the optional forms of tunneling; namely, Minimal Encapsulation [MIP-MINENC].
9. Mobile nodes de-registering upon returning to their home network.
10. Registrations being rejected for authentication failures, including invalid authenticators as well as mismatched identification values (replay protection).
11. TCP connections remaining open (with data flowing) while a mobile node moved from its home network to a foreign network and then back again to the home network.

Interoperability of at least two independent implementations was demonstrated for all of the features listed above. 🔥👑

7. Summary 🌟

the co-chairs, speaking for the working group participants, believe the Mobile IP working group has satisfied the requirements set forth in [RFC1264] for advancing Mobile IP to Proposed Standard RFC 💅 specifically: the technical specification document is stable, a MIB has been written, the security architecture was set forth in accordance with IAB principles, and several independent implementations were demonstrated to be interoperable 🫶

8. References 📚

• [RFC1256] Deering, S., Editor, "ICMP Router Discovery Messages", RFC 1256, September 1991.
• [RFC1701] Hanks, S. et. al., "Generic Routing Encapsulation (GRE)", RFC 1701, October 1994.
• [RFC1264] Hinden, R., "Internet Routing Protocol Standardization Criteria", RFC 1264, October 1991.
• [MIP-IPinIP] Perkins, C., Editor, "IP Encapsulation within IP", RFC 2003, October 1996.
• [MIP-OPTIM] Johnson, D., and C. Perkins, "Route Optimization in Mobile IP", Work in Progress.
• [MIP-PROTO] Perkins, C., Editor, "IP Mobility Support", RFC 2002, October 1996.
• [MIP-MINENC] Perkins, C., Editor, "Minimal Encapsulation within IP", RFC 2004, October 1994.

9. Author's Address 📮

questions about this memo go to:

   Jim Solomon
   Motorola Inc.
   1301 E. Algonquin Rd. - Rm 2240
   Schaumburg, IL  60196

   Voice:  +1-847-576-2753
   Fax:    +1-847-576-3240
   EMail: solomon@comm.mot.com

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