Subject: [seamoby] updated problem statement

From: Phil Roberts <[email-masked]>
Date: Wed, 2 May 2001 19:22:34 -0400

I just submitted this to internet drafts.  Text included below.
Incorporated changes from several people including most of michael's
comment.  

   Personal                                                P. Roberts 
                                                           Compiler 
   Internet Draft                                     
   Title: draft-proberts-localsubnetmobility-         
problem-00.txt 
   Category: Informational                                  May 2001 
   Expires : November 2001                            

                        Local Subnet Mobility Problem Statement 
                    <draft-proberts-localsubnetmobility-problem-00.txt> 

   Status of This Memo 

   This document is an Internet-Draft and is in full conformance with 
   all provisions of Section 10 of RFC2026.  Internet-Drafts are working 
   documents of the Internet Engineering Task Force (IETF), its areas, 
   and its working groups.  Note that other groups may also distribute 
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                                 Abstract 
    
   This document specifies a problem statement for investigation within 
   the IRTF.  There are a couple of seemingly unrelated problems that 
   have led investigators to converge on the desirability of 
   implementing a routing protocol whose purpose is to allow a mobile 
   node to retain connectivity via its current IP subnet while it moves 
   within the scope of the micro mobility domain. In general this domain 
   is expected to be contained within an autonomous system so that 
   global aggregation of subnets is still preserved. An additional 
   benefit of the protocols is that mobile nodes may more quickly react 
   to failed links.  The problem is to investigate the limits and issues 
   with using (a) new protocol(s) to implement per node routes to 
   facilitate better the movement of nodes and recovery of the network 
   in the presence of failed links or routers.  The document is a brief 
   statement of the problem to be investigated with references to lots 
   of other work that has been done already by many others in the area.   

                                                                     1 
Internet Draft Local Subnet Mobility Problem Statement       May 2001 

    
1. Introduction 
    
   The design of Internet routing has evolved largely based on the 
   assumption that most end systems are stationary. As the idea of 
   mobile devices came along, Mobile IP provided an easy migration path 
   for supporting end system mobility without significant change or 
   impact to the Internet infrastructure. This was achieved primarily by 
   placing the support for routing to mobile devices on the end systems 
   and at a limited number of centralized points within the 
   infrastructure, effectively "hiding" the end system mobility from the 
   infrastructure routing protocols. However, as we anticipate the 
   desire to support real-time traffic flows to mobile devices and the 
   possibility that mobile devices may become a significant portion of 
   all Internet end nodes, investigation of alternative designs merit 
   consideration. Many investigators in this area have converged on 
   solutions that propose the use of local subnet mobility routing to 
   support mobility within a limited domain, effectively exposing the 
   mobility of end systems to the routers. 
    
   This draft represents a problem statement to enable investigation of 
   how a local subnet mobility routing protocol can be employed to 
   enable mobility and fast network recovery.  It is a problem statement 
   based on a lot of work done in attempting to provide low latency 
   handover in mobile networks and fast recovery in networks with fast 
   recovery requirements.  Please see the reference list for a large set 
   of work that has been done in the past along these lines. 
    
   A good summary of the problem as it pertains to network recovery is 
   [MC].  The micromobility design team of the seamoby working group 
   produced a problem statement also [SMM].  See the reference list for 
   lots of previous work that has been done especially in the area of 
   mobility with alternate proposals from Mobile IP. 
    
2. Problem Statement 
    
   This section proposes questions that have led to a perceived need for 
   investigation of node routing within the IRTF.  Why is there a 
   perceived need for a non-tunnel-based routing solution for mobility?  
   While Mobile IP provides transparency of the mobility to 
   correspondent nodes communicating with hosts on the mobile network, 
   Mobile IP does not provide transparency for any state contained 
   within routers along the paths from correspondent nodes and the 
   mobile node's home agent. That is, state in routers which is 
   dependent on the stability of the source or destination address in 
   the IP header will be negatively impacted by the mobile node's change 
   of care of addresses. For example, when a mobile node changes its 
   care of address, the mobile node's current reservation would require 
   that the filter specs be updated with the new care of address. By 
   instead treating the mobility as a topology change within the local 
   area, these unpleasant second order effects can be avoided.  

Design Team                                                          2 
Internet Draft Local Subnet Mobility Problem Statement       May 2001 

2.1 Problem One  
    
   There are applications that involve supporting real-time traffic 
   flows to end devices that are mobile.  These applications require 
   that there be minimal (ideally no) interruption to the packet flows 
   and that these flows need to preserve the existing QoS and security 
   characteristics as the end station moves.  In addition the movement 
   of the end devices should not cause excessive signaling in the 
   network as the devices move.  Such applications often also run on 
   networks in which link failures or router failures can cause a 
   significant service disruption.  Is it possible to use a similar 
   protocol to allow for faster restoration of service during link 
   failures.  Could such mobility requirements and fast restoration 
   requirements be met in a way that is more efficient and simpler than 
   approaches based on Mobile IP and current intradomain routing 
   protocols by using a routing protocol that implements local subnet 
   mobility within a limited scope within the network?  What would the 
   limits of such a solution be in terms of scaling?  Specifically how 
   many nodes could be supported across what kind of network breadth and 
   depth at what cost of complexity in the routers around the edge of 
   such a network?  Is it possible to meet traffic engineering 
   requirements using such a protocol?  Could it simplify management of 
   QoS in the part of the network where mobility is most readily felt? 
    
2.2 Problem Two 
    
   One of the primary principles of the Internet has been end-to-end  
   communication. Most (if not all) of the protocols running over IP 
   have been designed with end-to-end signaling in mind.  Currently, 
   changes due to mobility induce unwanted end-to-end signaling. This 
   may cause applications running over IP to fail due to delay and 
   latency induced by unwanted signaling.  Security, QoS and AAA 
   signaling all suffer due to this.  Could a local subnet mobility 
   protocol aid in this respect? 
    
2.3 Problem Three 
    
   Why is there a need for an investigation of it in the IRTF rather 
   than a direct move to work on a standard within a working group of 
   the IETF?  The area directors overseeing the activities of the 
   seamoby working group and the mobile-ip working group have raised 
   questions about the scale of local subnet mobility routing and the 
   potential need to introduce both another routing protocol and another 
   mobility protocol. A comparison with existing mobility management and 
   routing protocols are involved in making such an assessment both in 
   terms of relative scalability, performance, and complexity. 

3. Acknowledgements 
    
   The compiler would like to acknowledge all the contributors who have 
   produced work relating to host routing for the various problems.   

Design Team                                                          3 
Internet Draft Local Subnet Mobility Problem Statement       May 2001 

References 
    
    [MC] M. Scott Corson, A. O'Neill, G. Tsirtsis.  IP Fast Restoration.  
Work in Progress.  Draft-corson-fastrestore-00.txt, November 2000. 
    [SMM] J. Loughney, et. al.  "SeaMoby Micromobility Problem 
Statement."  Work in Progress.  Draft-ietf-seamoby-mm-problem-01.txt, 
February 2001. 
    [FHO] G. Tsirtsis, et. al.  "Fast Handovers for Mobile Ipv6."  Work 
in Progress.  Draft-ietf-mobileip-fast-mipv6-00.txt, February 2001. 
    [MT] M. Thomas.  "Analysis of Mobile IP and RSVP Interactions."  
Work in Progress.  Draft-thomas-seamoby-rsvp-analysis-00.txt, February 
2001. 
    [CI] Z. Shelby, et. al.  "Cellular IP v6."  Work in Progress.  
Draft-shelby-seamoby-cellularipv6-00.txt, November 2000. 
    [HSR] A. O'Neill.  "Host Specific Routing."  Work in Progress.  
Draft-oneill-li-hst-00.txt, November 2000. 
    [IMMP] A. Campbell and J. Gomez.  "IP Micro-mobility Protocols."  
ACM SIGMOBILE Mobile Computer and Communications Review (MC2R), 2001, 
available at http://www.comet.columbia.edu/micromobility. 
    [CIP] Campbell, et. al.  "Cellular IP."  Work in Progress.  Draft 
expired, but available at http://www.comet.columbia.edu/micromobility. 
    [HAW] Ramjee, et. al.  "Hawaii."  Work in Progress.  Draft expired, 
but available at http://www.comet.columbia.edu/micromobility. 
    [EMA] M. Scott Corson, and Alan O'Neill. An Approach to Fixed/Mobile 
   Converged Routing. University of Maryland, Institute for Systems 
Research, 
   Technical Report, TR 2000-5. 2000. available at 
   http://www.isr.umd.edu/TechReports/ISR/2000/TR_2000-5/TR_2000-5.phtml 

Addresses 
    
   The compiler of this document is: 
    
   Phil Roberts, Megisto Systems, Inc., [email-masked] 

Design Team                                                          4

---

From: Arthur Ross <[email-masked]>
Date: Wed, 2 May 2001 16:56:38 -0700

>Incorporated changes from several people including most of michael's
Phil -

I think this has converged on a very good, clear summary of the issues.
While I would like some more explicit mention of support for radio-ish
issues, the statements about QoS can be interpreted broadly to include
those sorts of things, without attempting to pre-bias the solution.

Again, good job by all.

   -- ahmr