Mobile IPv6 Extensions (mext) C. Perkins
Internet-Draft Tellabs
Intended status: Informational Dapeng. Liu
Expires: January 10, 2012 China Mobile
Jul 9, 2011
DMM Comparison Matrix
draft-perkins-dmm-matrix-01
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
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This Internet-Draft will expire on January 10, 2012.
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the Trust Legal Provisions and are provided without warranty as
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Matrix Comparing Existing Approaches for DMM . . . . . . . . . 4
3. Explanations for Matrix Entries . . . . . . . . . . . . . . . 5
3.1. Route Optimization . . . . . . . . . . . . . . . . . . . . 5
3.2. Source address selection refinements . . . . . . . . . . . 6
3.3. Dynamically allocated home agent . . . . . . . . . . . . . 7
3.4. Binding updates to CN even without HA . . . . . . . . . . 8
3.5. Transport protocol Mobility . . . . . . . . . . . . . . . 8
3.6. Local anchor . . . . . . . . . . . . . . . . . . . . . . . 9
4. Security Considerations . . . . . . . . . . . . . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6. Normative References . . . . . . . . . . . . . . . . . . . . . 10
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 10
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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.
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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.
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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 may be 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.
3.1. Route Optimization
Mobile IPv6 supports route optimization and bi-directional tunneling.
Using route optimization, 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: Using route optimization, the signalling and data do
not have to be sent through the centralized mobility anchor.
Since the effect of route optimization is to reduce traffic
through the home network, scalability is improved. Moreover,
route optimization can reduce the effect of the home agent as a
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single point of failure.
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
Source address selection refinements (SAddrSel): MN picks source
address appropriate for current point of attachment when launching an
application.
1. Scalability: Since the MN can pick a local source address,
packets to/from the MN do not have to traverse the home network,
improving scalability and reducing delay.
2. Specified: see [RFC3775]
3. IP address continuity: If the MN uses a local source address, IP
address continuity is likely to be violated when MN moves to a
new network where that address is no longer addressable.
4. backhaul friendly: Since packets do not have to traverse the home
network, this solution is more backhaul friendly.
5. app friendly: since applications are likely to require changes in
order to make the address selection, this solution is less app-
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friendly. If source addresses are selected without involvement
of the application, this effect would be eliminated.
6. server-friendly: The source address selection by the application
does not involve the server.
7. local routing: Using a local source address enables local routing
for local services and communication partners.
8. low signaling: This solution does not impose any signaling
signaling requirement, unless the address selection algorithm
requires policy management by the operator.
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 afterwards. If the MN selected a new home agent, it is
likely that existing communications through the previous home agent
would be disrupted.
IP address continuity: When mobile node changes location, it may
choose a new home agent, but home address would also need to change
accordingly, making IP address continuity unlikely.
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 selects the nearest home agent, it
can support local routing through that home agent.
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Low signaling: Dynamic discovery and assignment of a home agent may
need additional signaling.
3.4. Binding updates to CN even without HA
Binding updates to CN even without HA (CN-wo-HA): Similar to route
optimization, but does not require protocol signaling with home
agent.
1. Scalability: yes, same as for route optimization.
2. Specified: Internet drafts exist, but no working group document.
3. IP address continuity: yes, same as for route optimization.
4. backhaul friendly: yes, same as for route optimization.
5. app friendly: yes, same as for route optimization.
6. server-friendly: no, same as for route optimization.
7. local routing: yes, same as for route optimization.
8. low signaling: no, same as for route optimization.
3.5. Transport protocol Mobility
Transport protocol (Trans-Mob): MN modifies transport (e.g., TCP,
SCTP, DCCP, MPTCP) protocol parameters to change the IP address of
transport connection endpoint. In many ways, such approaches
resemble CN-wo-HA except that the signaling occurs at a different
layer of the protocol stack (namely, at the transport layer instead
of the network layer).
1. Scalability: yes, same as for CN-wo-HA.
2. Specified: no, same as for CN-wo-HA.
3. IP address continuity: The point of such approaches is,
basically, to eliminate the need for IP address continuity. So,
while IP address continuity is not provided, this should not be
considered a demerit of transport mobility approaches. It would
be better to compare approaches based on "session continuity"
instead of "IP address continuity".
4. backhaul friendly: yes, same as for CN-wo-HA.
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5. app friendly: yes (typically), same as for CN-wo-HA.
6. server-friendly: no, same as for CN-wo-HA.
7. local routing: yes, same as for CN-wo-HA.
8. low signaling: MIPv6 RO mode use the return routability
procedure. which requires more signalling than MIPv6 bi-
directional tunnel mode.
3.6. Local anchor
Local anchor (Anchor-Mob): Local mobility anchor (e.g., MAP in HMIP
[RFC5380]) available for use by MN at its current point of
attachment.
1. Scalability: The mobile node signals the nearest anchor. MNs in
other networks can use different anchors. Scalability is
improved because the signaling path between the mobile node and
its local anchor is shorter. Moreover, local mobility anchors
offload work from any remote mobility anchor such as the home
agent.
2. Specified: HMIP[RFC5380]
3. IP address continuity: In conjunction with Mobile IPv6 as a macro
mobility protocol, IP address continuity is enabled.
4. backhaul friendly: The mobile node can choose the nearest local
anchor; in this sense, it is backhaul friendly.
5. app friendly: application does not need to change to support
dynamically allocated home agent. So it is app friendly.
6. server-friendly: server does not need to change to support local
mobility anchor, so it is server friendly.
7. Local routing: Generally, the use of a local anchor does not
necessarily improve local routing; additional functionality would
need to be designed or included with the local anchor.
8. Low signaling: Additional signaling is required for the mobile
node to insert new bindings at the local anchor.
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4. Security Considerations
This document does not have any security considerations.
5. IANA Considerations
This document does not have any IANA actions.
6. Normative References
[RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003.
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
[RFC5380] Soliman, H., Castelluccia, C., ElMalki, K., and L.
Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility
Management", RFC 5380, October 2008.
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
Charles E. Perkins
Tellabs
Phone: +1-408-421-1172
EMail: charliep@computer.org
Dapeng Liu
China Mobile
Phone: +86-123-456-7890
EMail: liudapeng@chinamobile.com
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