One document matched: draft-chan-lisp-pmip-00.txt
Network Working Group H. Chan
Internet-Draft Huawei Technologies
Intended status: Informational October 19, 2010
Expires: April 22, 2011
Integrating PMIP into LISP Network
draft-chan-lisp-pmip-00
Abstract
PMIP and LISP are both network-based. Integration of PMIP with a
hierarchical design into the LISP network provides network-based
fast-mobility support to enable a mobile node to perform handover in
both LISP and non-LISP networks, and non-optimal PMIP routes in the
LISP network are avoided.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. PMIP in a non-LISP network and comparison with LISP . . . . . 3
4. PMIP in a LISP network . . . . . . . . . . . . . . . . . . . . 5
4.1. MN being stationary at its home link . . . . . . . . . . . 6
4.2. MN handover within its home network . . . . . . . . . . . 7
4.3. MN handover to a visited LISP network . . . . . . . . . . 8
4.4. MN handover within a visited LISP network . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Normative References . . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
The Locator/ID Separation Protocol (LISP) [I-D.ietf-lisp] belongs to
the family of protocols to distinguish between routing locators
(RLOCs) and endpoint identifiers (EIDs) and maintains a mapping
between them. It takes a network-based approach by using RLOC for
routing in the transit core networks and EID within a network.
Therefore a site may, among other things, use its EID as a stable
identifier even upon change of its RLOC.
In comparison, Mobile IP (MIP) [RFC3775], also distinguishes between
a care-of-address (CoA) and a home address (HoA) of a mobile node
(MN) and maintains a mapping between them at the home agent in the
home network. The CoA is used for routing and may change as the
mobile node changes its attachement. The mobile node may then use
the stable home address as a session identifier so that the IP
session is not broken upon change of routing address. The network-
based variant of MIP is proxy mobile IP (PMIP) [RFC5213], which
replaces the CoA of the MN with the routing address is the proxy-CoA
of a mobile access gateway (MAG) which performs the mobility
signaling on behalf of the MN.
Because both LISP and PMIP are network based and because PMIPv6 is
designed to support mobility in non-LISP network, integrating PMIPv6
into the LISP network will provide network-based mobility in both
LISP and non-LISP networks.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. PMIP in a non-LISP network and comparison with LISP
PMIP for an MN in a non-LISP network is illustrated by comparing it,
which is shown in Figure 1(b), with LISP, which is shown in Figure
1(a).
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(b) PMIP in
(a) LISP network non-LISP network
+-------+ +--------+
|Mapping| |Mapping |
|system | |system |
.+-------+ + +
. . | |
. . | |
. . | |
+-------+ +-------+ + +
| |------| | | |
| ITR |tunnel| ETR | |Mobility|
| |------| | | anchor |
+-------+ +-------+ +--------+
^ | / |t|
| | | |u|
| v | |n|
| +-------+ | |n|
| | site | / |e|
| +-------+ | |l|
| | | +-------+
| | | | MAG |
| | / +-------+
| | | |
| | | |
| v | v
+-------+ +-------+ +---+ +-------+
+Sender + | host | |CN | | MN |
+-------+ +-------+ +---+ +-------+
Figure 1. (a) LISP network, (b) PMIP in non-LISP network.
Both LISP and PMIP use map and encapsulation. Yet there are also
differences between them.
In LISP, the mapping is between the site prefix, which is the EID,
and the RLOC of the ETR serving the site. In PMIP, the mapping is
between the home address (HoA) of MN and the proxy CoA of the MAG
serving the MN.
In LISP, the ITR queries the map server through a map resolver. The
ITR then tunnels the packet to the ETR, which will deliver the packet
to the site. In PMIP, the mapping information is located at the
mobility anchor so that the mobility anchor will tunnel the packet to
the MAG, which will then deliver the packet to the MN.
In LISP, the source of information on how to deliver packet to the
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site is kept at the ETR, and the ETRs in different networks provide
these information to the mapping system. The ITR queries the mapping
system only when needed. In PMIP, the source of information on where
the MN is located is at the MAG, and the different MAGs provide these
information to the mapping information system that is located in the
mobility anchor.
In LISP, routing is via the ETR that serves the site so that the
route is already optimized. Yet in PMIP, the mobility anchor can be
far from both the CN and the MN so that the route via the mobility
anchor can be far from being optimal.
4. PMIP in a LISP network
The MN can be in either a non-LISP network or a LISP network. The
senario with the MN in a non-LISP network is already shown in Figure
1(b). We therefore only need to consider the senario in which the MN
is in a LISP network.
The integration of PMIP into the LISP network is illustrated in
Figure 2. A hierarchy is introduced into the PMIP using the concept
of hierarchical MIP (HMIP) [RFC5380].
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+-------+ Add mapping between
|Mapping| HoA of MN and
|system | RLOC of ETR
.+-------+
. .
. .
. .
+-------+ +-------------------------------+
| |------| Add mapping between |
| ITR |tunnel| ETR HoA of MN and |
| |------| Proxy CoA of MAG |
+-------+ +-------------------------------+
^ | |t|
| | |u|
| v |n|
| +-------+ |n|
| | site | |e|
| +-------+ |l|
| | +-------+
| | | MAG |
| | +-------+
| | |
| | |
| v v
+-------+ +-------+ +-------+
+ CN + | host | | MN |
+-------+ +-------+ +-------+
Figure 2 Integrating a hierarchy of PMIP into LISP network.
In the LISP network, two levels of hierarchy are involved. The LISP
mapping system and the LMA both keep the mapping between the HoA of
the MN and the RLOC of the new ETR; the ETR keeps the mapping between
the HoA of the MN and the proxy CoA of the MAG. In terms of the role
of maintaining the mapping information, the ETR behaves like a LMA to
the MAG, whereas the LISP mapping system behaves like a LMA to the
ETR.
It is certainly possible to run PMIP without this hierarchy. Yet
utilizing this hierarchy in the LISP network enables route
optimization. In addition, it also significantly reduces the amount
of mapping updates in the LMA because the majority of handovers are
expected to be between two MAG's under the same ETR.
4.1. MN being stationary at its home link
When an MN first attaches to a network, it may obtain an IP address
(HoA) from that network, which is its home network. As long as MN
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does not move away from this home link, routing to reach this MN does
not need tunneling in this network. This situation is the same for
both the LISP network and the non-LISP network.
The LISP mapping system is therefore not affected.
A related senarios is as follows: The MN may first attach to a site
in a LISP network and obtain a globally unique IP address (HoA) from
the site. The site may be using a provider independent network
prefix so that it is supported by LISP to change provider or to
multi-home to different provider networks. The MN may move within
the site, and the reachability of the MN within this site may be
managed by the site itself. Then LISP is again not affected.
4.2. MN handover within its home network
When an MN performs handover within its home network, it may continue
to use its HoA using PMIP. If this home network is a LISP network
served by an ETR, the ETR acts at the mobility anchor as illustrated
in Figure 3. An equivalent way to look at it is that the LMA
funciton co-locates with the ETR. To the MAG, the ETR behaves like
the local mobility anchor (LMA) defined in PMIP. The tunneling is
between the ETR and the new MAG using the proxy CoA of the MAG.
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+-------+
|Mapping|
|system |
.+-------+
. .
. .
. .
+-------+ +-------------------------------+
| |------| Add mapping between |
| ITR |tunnel| ETR HoA of MN and |
| |------| Proxy CoA of MAG |
+-------+ +-------------------------------+
^ | |t|
| | |u|
| v |n|
| +-------+ |n|
| | site | |e|
| +-------+ |l|
| | +-------+
| | | MAG |
| | +-------+
| | |
| | |
| v v
+-------+ +-------+ +-------+
+ CN + | host | | MN |
+-------+ +-------+ +-------+
Figure 3 MN running PMIP in LISP home network.
As long as the MN is within its home network, the LISP mapping system
is unaffected. That is, the senario in Figure 3 is a simplified
version of Figure 2 with which the LISP mapping system does not need
an additional entry for the MN.
The above senario includes the case in which the MN originally
attaches to a site supported by LISP and then leaves the site but is
under the same ETR as the site.
4.3. MN handover to a visited LISP network
An MN that has moved to a new LISP network could simply use a new IP
from the new network so that the new network has now become its new
home network. Yet the MN may need to use its HoA which it has
acquired from the previous network. The LISP mapping system needs to
keep an updated mapping between the HoA of the MN and the RLOC of the
ETR of the visited network. The ETR also needs to keep an updated
mapping between the HoA of the MN and the proxy CoA of the new MAG.
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The new MAG needs to perform proxy binding update with the new ETR on
behalf of the MN, whereas the new ETR needs to perform both a mapping
update with the LISP mapping system and a proxy binding update with
the LMA of the MN. The update to the LISP mapping system ensures
that packets destined to the MN are forwarded to the ETR of the
visited network, whereas the update with the LMA ensures that packets
originating from non-LIST network will also be forwarded to this ETR.
4.4. MN handover within a visited LISP network
After a handover to a visited LISP network, the MN may peform
additional handovers within that visited network. When the MN
performs such handover from one MAG to another MAG under the same ETR
in the visited LISP network, only the mapping system at the ETR needs
to update the binding between the HoA of the MN and the proxy CoA of
the new MAG. The new MAG performs proxy binding update with the ETR
on behalf of the MN. This senario is a simplified version of Figure
2 in which the LISP mapping system does not need further update.
5. Security Considerations
TBD
6. IANA Considerations
None
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
7.2. Informative References
[I-D.ietf-lisp]
Farinacci, D., Fuller, V., Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol (LISP)",
draft-ietf-lisp-09 (work in progress), October 2010.
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
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and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC5380] Soliman, H., Castelluccia, C., ElMalki, K., and L.
Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility
Management", RFC 5380, October 2008.
Author's Address
H Anthony Chan
Huawei Technologies
1700 Alma Ave
Plano, TX 75075
USA
Email: h.a.chan@ieee.org
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