DMM Comparison Matrix
draft-perkins-dmm-matrix-00

Abstract

Distributed Mobility Management (DMM) is proposed as a way to enable scalable growth of mobile core networks so that network service providers can meet new requirements for performance and reduced operational expenditures. This requires reconsideration of existing approaches within the IETF and elsewhere in order to determine which if any such approaches may be used as part of a DMM solution.

Status of this Memo

This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

Copyright Notice

Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document.

Table of Contents

• 1. Introduction
• 2. Matrix Comparing Existing Approaches for DMM
• 3. Explanations for Matrix Entries
• 3.1. Route Optimization
• 3.2. Source address selection refinements
• 3.3. Dynamically allocated home agent
• 3.4. Binding updates to CN even without HA
• 3.5. Transport protocol
• 3.6. Local anchor
• 4. Security Considerations
• 5. IANA Considerations
• 6. References
• 6.1. Normative References
• 6.2. Informative References
• Appendix A. Acknowledgements
• Authors' Addresses

1. Introduction

The goal of this document is to identify and compare known existing approaches for Distributed Mobility Management (DMM). Characterizations of each of the various methods selected for comparison are provided in a matrix form according to whether or not they meet certain criteria.

Efforts within the IETF have been launched to find improved mobility management by decentralizing some or all of the traditional functions associated with mobility, including handovers, location management, identification, and so on.

The following abbreviations appear in this document:

MN: mobile node

HA: home agent

CN: correspondent node

FQDN: Fully Qualified Domain Name

The following approaches to mobility management are characterized:

Route optimization (RO): MN supplies Binding Updates directly to CN.[RFC3775]

Source address selection refinements (SAddrSel): MN picks source address appropriate for current point of attachment when launching an application.

Dynamically allocated home agent (DynHA): Mobility anchor for MN is allocated on demand.

Binding updates to CN even without HA (CN-wo-HA): Similar to RO, but does not require protocol signaling with home agent.

Transport protocol (Trans-Mob) : MN modifies transport (e.g., TCP, SCTP, DCCP, MPTCP) protocol parameters to change the IP address of transport connection endpoint

Local anchor (Anchor-Mob): Local mobility anchor (e.g., MAP in HMIP [RFC5380]) available for use by MN at its current point of attachment.

Dynamic DNS (DynDNS): When MN gets a new address, DNS is updated so that the MN's FQDN resolves to that new address.

The approaches listed above will be characterized according to the following criteria:

1. scalability: in # of nodes
2. specified?: whether there is a working group document specifying the approach
3. IPadd continuity: provides stable IP address
4. backhaul friendly: reduces burden on backhaul
5. app friendly: apps do not require new code
6. server-friendly: server state minimized, servers do not require new code
7. local routing: "local breakout" / "hairpinning" / local traffic routed locally
8. low signaling: not too much signaling required

2. Matrix Comparing Existing Approaches for DMM

The following matrix rates the approaches described in the the previous section according to the characteristics listed.

                  RO  SAddr  DynHA  CN-wo-HA  Trans  Anchor  DynDNS
                       Sel                     Mob    Mob

scalability        Y    Y      M       Y        Y      M       M

specified?         Y    N      N       N        Y      Y       Y

IPadd continuity   Y    N      N       Y        Y      Y       N

backhaul friendly  Y    Y      Y       Y        Y      M       Y

app friendly       Y    N      Y       Y        N      Y       M

server-friendly    M    Y      Y       Y        N      Y       Y

local routing      Y    Y      M       Y        Y      N       Y

low signaling      N    Y      M       N        N      N       N

     Table 1: Comparison Matrix [Legend: Y=Yes, N=No, M=Maybe]

3. Explanations for Matrix Entries

Most of the matrix entries are relatively self-evident. For instance, "Trans Mob" (Transport-based Mobility) approaches are rated as not "app friendly" because applications require changes in order to make use of the approach.

For approaches that are identified generically, it is ambiguous whether or not they are properly specified in any working group document. Here, such approaches are characterized as specified if any particular approach in the generic family is specified. More detail may be needed in the future, in which case more columns or a new table may be needed.

In this initial pre-release of the document, not too many explanations have been supplied. If the document is considered worthwhile, explanations for more matrix entries will be developed, concentrating first on those entries which have received mailing list attention.

3.1. Route Optimization

Mobile IPv6 supports route optimization mode and bi-directional tunnel mode. In route optimization mode, the mobile node can send mobility signalling and subsequently data packets directly to the correspondent node. The following aspects of route optimization are characterized in the comparison matrix.

1. Scalability: In route optimization mode, the signalling and data could be sent without through the centralized mobility anchor. So there is no single point of failure in RO mode. Moreover, the effect of route optimization is to reduce traffic through the home network -- therefore there is no scalability issue.
2. Specified: RFC 3775 specifies the route optimization mode of MIPv6.
3. IP address continuity: In MIPv6 route optimization mode, the mobile node still uses the same home address as the bi-directional tunnel mode. RO mode supports IP address continuity.
4. backhaul friendly: In RO mode, the data can send directly to the CN. Data do not need to send through centralized moblity anchor, thence RO is backhaul friendly.
5. app friendly: RO mode does not require application changing, so it is application friendly.
6. server-friendly: RO mode requires the server (i.e., CN) to also support Mobile IP RO mode. In this sense, RO is not server friendly.
7. local routing: In RO mode, the data is forwarded directly between MN and CN, it thence can support local routing.
8. low signaling: MIPv6 RO mode use the return routability procedure. which requires more signalling than MIPv6 bi-directional tunnel mode.

3.2. Source address selection refinements

Dummy text here. Source address selection refinements (SAddrSel): MN picks source address appropriate for current point of attachment when launching an application.

3.3. Dynamically allocated home agent

Dynamically allocated home agent (DynHA): Mobility anchor for MN is allocated on demand.

Scalability: If the network supports dynamically allocated home agents, the mobile node can choose the nearest home agent. Other mobile nodes can use different home agents. But when changing location, home agent may not be able to change accordingly. The mechanism for associating home agents to mobile nodes can vary, and different algorithms have different scalability characteristics; some may be more scalable than others. Method relying on anycast addresses for home agents are among the more scalable approaches.

Specified: RFC 3775 specifies dynamic home agent address discovery and dynamic home prefix discovery. But it does not support changing home agent after the mobility session setting up.

IP address continuity: When mobile node changes location, it may choose a new home agent, but home address would also need to change accordingly.

backhaul friendly: The mobile node can choose the nearest home agent, in this sense, it is backhaul friendly.

app friendly: application does not need to change to support dynamically allocated home agent. So it is app friendly.

server-friendly: server does not need to change to support dynamically allocated home agent, so it is server friendly.

Local routing: When mobile node selecting the nearest home agent, it can support local routing in some degree.

Low signaling: Dynamical discovery and assignment of a home agent may need additionally signaling.

3.4. Binding updates to CN even without HA

Dummy text here. Binding updates to CN even without HA (CN-wo-HA): Similar to RO, but does not require protocol signaling with home agent.

3.5. Transport protocol

Dummy text here. Transport protocol (Trans-Mob) : MN modifies transport (e.g., TCP, SCTP, DCCP, MPTCP) protocol parameters to change the IP address of transport connection endpoint

3.6. Local anchor

Dummy text here. Local anchor (Anchor-Mob): Local mobility anchor (e.g., MAP in HMIP [RFC5380]) available for use by MN at its current point of attachment.

4. Security Considerations

This document does not have any security considerations.

5. IANA Considerations

This document does not have any IANA actions.

6. References

6.1. Normative References

6.2. Informative References

Appendix A. Acknowledgements

This document has benefitted from discussions with the following people, in no particular order: Seok Joo Koh, Jouni Korhonen, Julien Laganier, Dapeng Liu, Telemaco Melia, Pierrick Seite

Authors' Addresses