Internet DRAFT - draft-perkins-dmm-matrix
draft-perkins-dmm-matrix
Mobile IPv6 Extensions (mext) C. Perkins
Internet-Draft Tellabs
Intended status: Informational Dapeng. Liu
Expires: January 13, 2013 China Mobile
W. Luo
ZTE
July 13, 2012
DMM Comparison Matrix
draft-perkins-dmm-matrix-04
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
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 2, 2013.
Copyright Notice
Copyright (c) 2012 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
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Current Practice of DMM . . . . . . . . . . . . . . . . . . . 4
3. Matrix Comparing Existing Approaches for DMM . . . . . . . . . 5
4. Explanations for Matrix Entries . . . . . . . . . . . . . . . 6
4.1. Route Optimization . . . . . . . . . . . . . . . . . . . . 6
4.2. Source address selection refinements . . . . . . . . . . . 7
4.3. Dynamically allocated home agent . . . . . . . . . . . . . 8
4.4. Binding updates to CN even without HA . . . . . . . . . . 9
4.5. Transport protocol Mobility . . . . . . . . . . . . . . . 9
4.6. Local anchor . . . . . . . . . . . . . . . . . . . . . . . 10
4.7. HIP/LISP . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.8. Distributed anchor with direct tunnel . . . . . . . . . . 11
4.9. Per-Host Locators Mechanism . . . . . . . . . . . . . . . 12
5. Security Considerations . . . . . . . . . . . . . . . . . . . 13
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1. Normative References . . . . . . . . . . . . . . . . . . . 13
7.2. Informative References . . . . . . . . . . . . . . . . . . 14
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 14
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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.
Distributed anchor with direct tunnel (Dis-Anc): MN's current
anchor can be changed dynamically depends on current location of
MN (e.g. methods introduced in [I-D.chan-netext-distributed-lma],
[I-D.wakikawa-mext-global-haha-spec] and
[I-D.liu-dmm-pmip-based-approach]). Optimized routing is realized
by a direct tunnel between anchors of MN and its CN.
Per-Host Locators Mechanism (Host-Loc): By using identifier-
locator split mechanism to solve the routing above anchor level
and enable optimal routes to the mobile node's current mobility
anchor ([I-D.liebsch-mext-dmm-nat-phl])
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. Current Practice of DMM
Currently, IETF has specified mobile IP and its variants for mobility
managment. Current mobile IP protocol could be deployed in a
distributed way to best meet the requirment of DMM.
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Dynamic Anchoring approach:
Dynamic anchoring allows the application on the mobile node always
choose the closest anchor. The mobility anchors could be deployed in
a distributed way: for example, deploy the mobility anchors in the
access router level in an IP network or in the local gateway in 3GPP
LIPA/SIPTO network.
Both network based and client based mobile IP solution could use the
dynamic anchoring concept. There are common problems that need to be
considered for both network/client based distributed mobile IP
deployment. The problems include active session managment, source
address selection, CN initiate sessio etc.
Hierarchical mobile IP
Hierachical mobile IP was designed to reduce the signalling overhead
of mobile IP protocol by introducing regional mobility anchor. The
regional mobility anchor could also be deployed in a distributed way.
It shares the similar problems as mobile IP in terms of session
management, source address selection etc.
3. Matrix Comparing Existing Approaches for DMM
The following matrix rates the approaches described in the previous
section according to the characteristics listed.
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RO SAddr DynHA CN Trans Anchor DynDNS HIP/ Dis- Host
Sel wo-HA Mob Mob Mob LISP Anc -LoC
scalability Y Y M Y Y M M Y Y Y
specified? Y N N N Y Y Y Y N N
IPadd Y N N Y Y Y N Y Y Y
continuity
backhaul Y Y Y Y Y M Y M Y Y
friendly
app Y N Y Y N Y M N/Y Y Y
friendly
server M Y Y Y N Y Y N/Y Y Y
friendly
local Y Y M Y Y N Y M M M
routing
low N Y M N N N N N M M
signaling
Table 1: Comparison Matrix [Legend: Y=Yes, N=No, M=Maybe]
4. 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.
4.1. 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.
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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
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.
4.2. 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 [RFC3484]
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.
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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-
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.
4.3. 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.
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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.
Low signaling: Dynamic discovery and assignment of a home agent may
need additional signaling.
4.4. 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.
4.5. 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
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be better to compare approaches based on "session continuity"
instead of "IP address continuity".
4. backhaul friendly: yes, same as for CN-wo-HA.
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.
4.6. 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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4.7. HIP/LISP
HIP: Host Identity Protocol(RFC 4423); LISP: Locator/ID Separation
Protocol.
1. Scalability: HIP/LISP are both location/indentification
separation protocol. Both HIP/LISP can support large scale
deployment in HIP/LISP domain. But when a node running HIP/LISP
needs to communicate with other hosts that are not located in the
HIP/LISP domain, another mechanism is needed.
2. HIP is specified in RFC 4423[RFC5380]. LISP is specified in
[I-D.ietf-lisp].
3. IP address continuity: HIP/LISP both use host indentification for
addressing. The host can use a stable IP address for
identification and addressing, thence HIP/LISP can support IP
address continuity.
4. backhaul friendly: HIP/LISP both use routing address for packet
routing; there is no centralized anchor point in the data plane.
But for communication to other hosts which are not located in the
HIP/LISP domain, a gateway function is needed and the data
traffic is constrained to travel through the gateway.
5. app friendly: LISP does not require application modification.
HIP may require application modification [RFC 6317].
6. server-friendly: For mobile nodes, HIP may require server
modifications; LISP does not require server modification.
7. Local routing: For communication within the HIP/LISP domain, HIP/
LISP can support local routing since the routing is based on
routing prefix instead of host indentification and there is no
cent
8. ralized anchor point.
9. Low signaling: HIP/LISP need new signaling in the host/network to
support its function.
4.8. Distributed anchor with direct tunnel
1. Scalability: Mobile node's home network contains its first anchor
when MN is initialized. When MN moves to a visit network, it can
change its mobility anchor to a new anchor point which is located
in this visit network. The traffic will not go through mobile
node's home network when it is in visit network. No centralized
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mobility anchor is needed and scalability is improved. Besides,
dynamically allocated mobility anchor mechanism can also be
applied when mobile node is initialized in its home network.
2. Specified: Internet drafts exist, but no working group document.
3. IP address continuity: All mechanisms introduced in
[I-D.chan-netext-distributed-lma],
[I-D.wakikawa-mext-global-haha-spec] and
[I-D.liu-dmm-pmip-based-approach] are claimed to support IP
address continuity. I.e. additional mechanisms are used to
guarantee that mobile node can keeps its HoA unchanged even its
mobility anchor is changed.
4. Backhaul friendly: Mobile node can change it mobility anchor to a
best anchor point (e.g. a nearest anchor point) and packets do
not have to traverse the home network, this solution is more
backhaul friendly.
5. App friendly: Does not require application changing. Socket of
application is always binded to mobile node's HoA, so it is
application friendly.
6. Server-friendly: Does not require server changing, so it is
server friendly.
7. Local routing: Packets from mobile node to its correspondent node
shall go though mobile node's current mobility anchor. If the
mobility anchor is mobile node's first router, then local routing
is supported.
8. Low signaling: Additional signaling is needed for supporting
location management approaches and handoff approaches. It can be
excepted that number of signaling may increase with growth of
mobile node's number. It depends on the specific design.
4.9. Per-Host Locators Mechanism
1. Scalability: As claimed in [I-D.liebsch-mext-dmm-nat-phl], mobile
node are supported to change its current mobility anchor, i.e.
when mobile node is not at home, packet will not go through its
home network which is similar with Dis-Anc. So it is Yes.
2. Specified: Internet drafts exist, but no working group document.
3. IP address continuity: Mobile node can keep its HoA unchanged, so
IP address continuity is guaranteed. How to guarantee limited
packet loss rate when mobile node changes its current anchor
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point is not very clear now.
4. Backhaul friendly: Yes. The reason is same as Dis-Anc.
5. App friendly: Yes. The reason is same as Dis-Anc.
6. Server-friendly: Yes. The reason is same as Dis-Anc.
7. Local routing: Maybe. The reason is same as Dis-Anc.
8. Low signaling: The mechanism is based on NAT to guarantee per-
host locators. How to guarantee the synchronization of NAT
status is un-clear now. But it can be excepted that additional
signaling is necessary.
5. Security Considerations
This document does not have any security considerations.
6. IANA Considerations
This document does not have any IANA actions.
7. References
7.1. Normative References
[I-D.ietf-lisp] Farinacci, D., Fuller, V.,
Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol
(LISP)", draft-ietf-lisp-23
(work in progress), May 2012.
[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.
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[RFC4423] Moskowitz, R. and P. Nikander,
"Host Identity Protocol (HIP)
Architecture", RFC 4423,
May 2006.
[RFC5380] Soliman, H., Castelluccia, C.,
ElMalki, K., and L. Bellier,
"Hierarchical Mobile IPv6
(HMIPv6) Mobility Management",
RFC 5380, October 2008.
7.2. Informative References
[I-D.chan-netext-distributed-lma] Chan, H., Xia, F., Xiang, J.,
and H. Ahmed, "Distributed
Local Mobility Anchors", draft
-chan-netext-distributed-lma-
03, March 2010.
[I-D.wakikawa-mext-global-haha-spec] Wakikawa , R., Kuntz, R., Zhu,
Z., and L. Zhang, "Global HA to
HA Protocol Specification", dr
aft-wakikawa-mext-global-haha-
spec-02, September 2011.
[I-D.liu-dmm-pmip-based-approach] Liu, D., Song, J., and W. Luo,
"PMIP Based Distributed
Mobility Management Approach",
draft-liu-dmm-pmip-based-
approach-01, December 2011.
[I-D.liebsch-mext-dmm-nat-phl] Liebsch , M., "Per-Host
Locators for Distributed
Mobility Management", draft-
liebsch-mext-dmm-nat-phl-00,
October 2011.
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
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Authors' Addresses
Charles E. Perkins
Tellabs
Phone: +1-408-421-1172
EMail: charliep@computer.org
Dapeng Liu
China Mobile
Phone: +86-139-117-88933
EMail: liudapeng@chinamobile.com
Wen Luo
ZTE
Phone:
EMail: luo.wen@zte.com.cn
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