draft-ietf-nemo-home-network-models-02.txt   draft-ietf-nemo-home-network-models-03.txt 
Network Mobility P. Thubert Network Mobility P. Thubert
Internet-Draft Cisco Internet-Draft Cisco
Expires: August 8, 2005 R. Wakikawa Expires: September 16, 2005 R. Wakikawa
Keio University Keio University
V. Devarapalli V. Devarapalli
Nokia Nokia
February 7, 2005 March 18, 2005
NEMO Home Network models NEMO Home Network models
draft-ietf-nemo-home-network-models-02 draft-ietf-nemo-home-network-models-03
Status of this Memo Status of this Memo
By submitting this Internet-Draft, I certify that any applicable By submitting this Internet-Draft, I certify that any applicable
patent or other IPR claims of which I am aware have been disclosed, patent or other IPR claims of which I am aware have been disclosed,
and any of which I become aware will be disclosed, in accordance with and any of which I become aware will be disclosed, in accordance with
RFC 3668. RFC 3668.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on August 8, 2005. This Internet-Draft will expire on September 16, 2005.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). All Rights Reserved. Copyright (C) The Internet Society (2005). All Rights Reserved.
Abstract Abstract
This paper documents some usage patterns and the associated issues This paper documents some usage patterns and the associated issues
when deploying a Home Network for NEMO-enabled Mobile Routers, when deploying a Home Network for NEMO-enabled Mobile Routers,
conforming the NEMO Basic Support draft [8]. The aim here is conforming the NEMO Basic Support draft [8]. The aim here is
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and concepts . . . . . . . . . . . . . . . . . . . 5 2. Terminology and concepts . . . . . . . . . . . . . . . . . . . 5
3. General Expectations . . . . . . . . . . . . . . . . . . . . . 6 3. General Expectations . . . . . . . . . . . . . . . . . . . . . 6
4. MIP Home Network . . . . . . . . . . . . . . . . . . . . . . . 7 4. MIP Home Network . . . . . . . . . . . . . . . . . . . . . . . 7
5. NEMO Extended Home Network . . . . . . . . . . . . . . . . . . 8 5. NEMO Extended Home Network . . . . . . . . . . . . . . . . . . 8
5.1 Configuration . . . . . . . . . . . . . . . . . . . . . . 8 5.1 Configuration . . . . . . . . . . . . . . . . . . . . . . 8
5.2 Returning Home . . . . . . . . . . . . . . . . . . . . . . 9 5.2 Returning Home . . . . . . . . . . . . . . . . . . . . . . 9
5.3 Home Address from MNP . . . . . . . . . . . . . . . . . . 9 5.3 Home Address from MNP . . . . . . . . . . . . . . . . . . 9
5.4 Deployment Caveats . . . . . . . . . . . . . . . . . . . . 10 5.4 Deployment Caveats . . . . . . . . . . . . . . . . . . . . 10
5.4.1 MR side . . . . . . . . . . . . . . . . . . . . . . . 10 5.4.1 Mobile Router side . . . . . . . . . . . . . . . . . . 10
5.5 Applicability . . . . . . . . . . . . . . . . . . . . . . 10 5.5 Applicability . . . . . . . . . . . . . . . . . . . . . . 10
6. NEMO Aggregated Home Network . . . . . . . . . . . . . . . . . 11 6. NEMO Aggregated Home Network . . . . . . . . . . . . . . . . . 11
6.1 Configuration . . . . . . . . . . . . . . . . . . . . . . 11 6.1 Configuration . . . . . . . . . . . . . . . . . . . . . . 11
6.2 Returning Home . . . . . . . . . . . . . . . . . . . . . . 11 6.2 Returning Home . . . . . . . . . . . . . . . . . . . . . . 11
6.2.1 Returning Home by egress . . . . . . . . . . . . . . . 12 6.2.1 Returning Home by egress . . . . . . . . . . . . . . . 12
6.2.2 Returning Home by ingress . . . . . . . . . . . . . . 12 6.2.2 Returning Home by ingress . . . . . . . . . . . . . . 12
6.3 Applicability . . . . . . . . . . . . . . . . . . . . . . 13 6.3 Applicability . . . . . . . . . . . . . . . . . . . . . . 13
6.4 Deployment Caveats . . . . . . . . . . . . . . . . . . . . 13 6.4 Deployment Caveats . . . . . . . . . . . . . . . . . . . . 13
6.4.1 HA Side . . . . . . . . . . . . . . . . . . . . . . . 13 6.4.1 Home Agent Side . . . . . . . . . . . . . . . . . . . 13
6.4.2 MR side . . . . . . . . . . . . . . . . . . . . . . . 14 6.4.2 Mobile Router side . . . . . . . . . . . . . . . . . . 14
7. Virtual Home Network . . . . . . . . . . . . . . . . . . . . . 15 7. Virtual Home Network . . . . . . . . . . . . . . . . . . . . . 15
7.1 Configuration . . . . . . . . . . . . . . . . . . . . . . 15 7.1 Configuration . . . . . . . . . . . . . . . . . . . . . . 15
7.2 Applicability . . . . . . . . . . . . . . . . . . . . . . 16 7.2 Applicability . . . . . . . . . . . . . . . . . . . . . . 16
8. Mobile Home . . . . . . . . . . . . . . . . . . . . . . . . . 17 8. Mobile Home . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.1 Configuration . . . . . . . . . . . . . . . . . . . . . . 17 8.1 Configuration . . . . . . . . . . . . . . . . . . . . . . 17
8.2 Applicability . . . . . . . . . . . . . . . . . . . . . . 18 8.2 Applicability . . . . . . . . . . . . . . . . . . . . . . 18
9. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 9. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.1 Changes from version 00 to 01 . . . . . . . . . . . . . . 20 9.1 Changes from version 00 to 01 . . . . . . . . . . . . . . 20
9.2 Changes from version 01 to 02 . . . . . . . . . . . . . . 20 9.2 Changes from version 01 to 02 . . . . . . . . . . . . . . 20
9.3 Changes from version 02 to 03 . . . . . . . . . . . . . . 20
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 22 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 22
A. Returning Home emulation in the virtual case . . . . . . . . . 23 A. Returning Home emulation in the virtual case . . . . . . . . . 23
Intellectual Property and Copyright Statements . . . . . . . . 24 Intellectual Property and Copyright Statements . . . . . . . . 24
1. Introduction 1. Introduction
This document assumes that the reader is familiar with IPv6 Mobility This document assumes that the reader is familiar with IPv6 Mobility
as defined in [7], with the NEMO Basic Support [8] and with the NEMO as defined in [7], with the NEMO Basic Support [8] and with the NEMO
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3. General Expectations 3. General Expectations
With Mobile IPv6, the Home Network is generally a physical network With Mobile IPv6, the Home Network is generally a physical network
interconnecting the Home Agents, and the Mobile Nodes that are at interconnecting the Home Agents, and the Mobile Nodes that are at
Home. NEMO extends the concept of Home so that it is not only a flat Home. NEMO extends the concept of Home so that it is not only a flat
subnet composed of Home Addresses but an aggregation that is itself subnet composed of Home Addresses but an aggregation that is itself
subnetted in mobile and Home Networks. This aggregation is still subnetted in mobile and Home Networks. This aggregation is still
referred to as Home. referred to as Home.
As an example, say that the aggregation has a global routing prefix As an example, considering the case where the aggregation has a
of m = 48 bits (A:B:C::/48), with subnet ID size of n = 16 bits ( n + global routing prefix of m = 48 bits (A:B:C::/48), with subnet ID
m = 64). size of n = 16 bits ( n + m = 64).
Say that a Mobile Router, MR1, owns the MNP A:B:C:1::/64: With NEMO When a Mobile Router, MR1, owns the MNP A:B:C:1::/64 with the NEMO
Basic Support, and depending on the deployment, MR1 may register Basic Support, MR1 may register using a Home Address from the Home
using a Home Address from the Home network, A:B:C:0::1, say, or a network (i.e. A:B:C:0::1) or a Home Address from one of its MNPs
Home Address, A:B:C:1::1, say, from one of its MNPs. (i.e. A:B:C:1::1) depending on the deployment.
In a given deployment, one subnet may be reserved for the Home Link In a given deployment, one subnet may be reserved for the Home Link
(say A:B:C:0::/64) while the others are attributed to Mobile Routers (A:B:C:0::/64) while the others are attributed to Mobile Routers as
as Mobile Networks (as A:B:C:1::/64 for MR1). Another approach could Mobile Networks (as A:B:C:1::/64 for MR1). Another approach could be
be to configure the Aggregation of Mobile Networks as the subnet on to configure the Aggregation of Mobile Networks as the subnet on the
the Home Link, and let the Mobile Routers manage the overlapping Home Link, and let the Mobile Routers manage the overlapping
networks. Finally, the aggregation could be configured on a virtual networks. Finally, the aggregation could be configured on a virtual
network, with no physical Home Link at all, in which case Home means network, with no physical Home Link at all, in which case Home means
topologically and administratively close to the Home Agent that owns topologically and administratively close to the Home Agent that owns
the virtual network. the virtual network.
The following sections provide additional information on these forms The following sections provide additional information on these forms
of Home Network. of Home Network.
4. MIP Home Network 4. MIP Home Network
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In the Extended Home Network model, the Home Network is configured on In the Extended Home Network model, the Home Network is configured on
a physical interface of the Home Agent, the Home Link. a physical interface of the Home Agent, the Home Link.
A Mobile Router returns Home by connecting directly to the Home Link, A Mobile Router returns Home by connecting directly to the Home Link,
and dropping the MRHA tunnel. and dropping the MRHA tunnel.
When at home, the Mobile Router ensures the connectivity of the When at home, the Mobile Router ensures the connectivity of the
Mobile Network using standard router operations. Mobile Network using standard router operations.
In implicit mode, the HA has the necessary information to continue In implicit mode, the Home Agent has the necessary information to
routing to the MNPs in the absence of registration, and the continue routing to the MNPs in the absence of registration, and the
participation of the MR to the Home IGP is not required. participation of the Mobile Router to the Home IGP is not required.
But in explicit mode, or if the MR uses an IGP over the MRHA tunnel, But in explicit mode, or if the Mobile Router uses an IGP over the
then it must resume its IGP operations on the Home Link in order to MRHA tunnel, then it needs to resume its IGP operations on the Home
advertise its Mobile Networks. Link in order to advertise its Mobile Networks to the HA, unless some
other means such as static routes are deployed to cover the case.
Alternate procedures for ensuring the connectivity of the Mobile Alternate procedures for ensuring the connectivity of the Mobile
Networks when at home are described in Section 7. Networks when at home are described in Section 7.
5.3 Home Address from MNP 5.3 Home Address from MNP
We saw that a natural extension of the MIP procedure is to derive the We saw that a natural extension of the MIP procedure is to derive the
Home Address of a Mobile Router from the prefix on the Home Link. Home Address of a Mobile Router from the prefix on the Home Link.
Alternatively, NEMO basic support allows that a Mobile Router forms Alternatively, NEMO basic support allows that a Mobile Router forms
its Home Address from one of its Mobile Network Prefixes. its Home Address from one of its Mobile Network Prefixes.
In that case, the Home Address does not match the Home Link Prefix, In that case, the Home Address does not match the Home Link Prefix,
and there is a need to configure the HA in a specific mode with the and there is a need to configure the Home Agent in a specific mode
support for the extended Home Network and the range of the Mobile with the support for the extended Home Network and the range of the
Network Prefixes. Based on that new configuration, the HA can accept Mobile Network Prefixes. Based on that new configuration, the Home
a Home Address that is not from the Home Link, and it will know that Agent can accept a Home Address that is not from the Home Link, and
it should not perform any DAD. it will know that it should not perform any DAD.
Also, if the MR uses a Home Address that is derived from its MNP, Also, if the Mobile Router uses a Home Address that is derived from
some specific support is required on the MR as well. In order to its MNP, some specific support is required on the Mobile Router as
determine that it is at Home, the MR recognizes the well-known prefix well. In order to determine that it is at Home, the Mobile Router
of its Home Agent as opposed to matching the prefix on the Home Link recognizes the well-known prefix of its Home Agent as opposed to
with that of its Home Address. matching the prefix on the Home Link with that of its Home Address.
When connecting to the Home Link, the MR also need to autoconfigure When connecting to the Home Link, the Mobile Router also need to
an address on the egress interface as opposed to assigning its Home autoconfigure an address on the egress interface as opposed to
Address to the interface. assigning its Home Address to the interface.
For all these reasons, this submode of extended is no more a trivial For all these reasons, this submode of extended is no more a trivial
extension to the MIPv6 Home Model, and it might not be compatible extension to the MIPv6 Home Model, and it might not be compatible
with all implementations. with all implementations.
5.4 Deployment Caveats 5.4 Deployment Caveats
5.4.1 MR side 5.4.1 Mobile Router side
In explicit mode, the routing to the MNP via the MR must be restored In explicit mode, the routing to the MNP via the Mobile Router must
when the MR is at Home. This is normally performed by the MR by be restored when the Mobile Router is at Home. This is normally
means of the existing IGP. In that case, a specific support is performed by the Mobile Router by means of the existing IGP. In that
required on the MR to control the routing protocol operation, case, a specific support is required on the Mobile Router to control
enabling the participation to the IGP if and only if the MR is at the routing protocol operation, enabling the participation to the IGP
home. This support might not be present in all implementations. if and only if the Mobile Router is at home. This support might not
be present in all implementations.
5.5 Applicability 5.5 Applicability
The extended Home Network keeps the MIP6 concept of a Home Network The extended Home Network keeps the MIP6 concept of a Home Network
for both Mobile Nodes and Mobile Routers to take their Home Address for both Mobile Nodes and Mobile Routers to take their Home Address
from. Since there is no overlap between the prefixes that are from. Since there is no overlap between the prefixes that are
affected to MNPs and prefix(es) that are dedicated to the Home Link, affected to MNPs and prefix(es) that are dedicated to the Home Link,
it is possible for MNs and MRs to coexist with that model. it is possible for MNs and Mobile Routers to coexist with that model.
Also, when the Home Address is derived from the prefix on the Home Also, when the Home Address is derived from the prefix on the Home
Link, the HA behavior on the link trivially extends that of MIP and Link, the Home Agent behavior on the link trivially extends that of
the support should for that configuration should be available with MIP and the support should for that configuration should be available
all implementations. with all implementations.
6. NEMO Aggregated Home Network 6. NEMO Aggregated Home Network
6.1 Configuration 6.1 Configuration
One other approach is to consider that the Aggregation of all the One other approach is to consider that the Aggregation of all the
MNPs is used plainly as the Home Link Prefix. In this model, the MNPs is used plainly as the Home Link Prefix. In this model, the
Home Network is referred to as a NEMO Aggregated Home Network. This Home Network is referred to as a NEMO Aggregated Home Network. This
means that the Mobile Aggregated Prefix is configured on the Home means that the Mobile Aggregated Prefix is configured on the Home
Link and advertised by the Home Agent as a subnet, as depicted in Link and advertised by the Home Agent as a subnet, as depicted in
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In that model, it seems natural to subnet the whole range of In that model, it seems natural to subnet the whole range of
addresses into Mobile Network prefixes, as opposed to reserving one addresses into Mobile Network prefixes, as opposed to reserving one
prefix for the Home Link, which would boil down to the Extended Home prefix for the Home Link, which would boil down to the Extended Home
Network model. If the prefix on the Home Link is really an Network model. If the prefix on the Home Link is really an
aggregation and not a final prefix, it should not be allowed for aggregation and not a final prefix, it should not be allowed for
autoconfiguration or Home Address allocation. autoconfiguration or Home Address allocation.
Note that in that case, it makes sense for a Mobile Router to Note that in that case, it makes sense for a Mobile Router to
register using a Home Address from one of its own MNPs. Taking the register using a Home Address from one of its own MNPs. Taking the
Home Address from its own range guarantees the uniqueness of the Home Address from its own range guarantees the uniqueness of the
suffix. That uniqueness can be checked by the MR on its ingress suffix. That uniqueness can be checked by the Mobile Router on its
network using DAD. ingress network using DAD.
6.2 Returning Home 6.2 Returning Home
The Aggregated Home Prefix is configured on a physical interface of The Aggregated Home Prefix is configured on a physical interface of
the Home Agent, the Home Link. As a consequence, the Home Agent has the Home Agent, the Home Link. As a consequence, the Home Agent has
a connected route to the Aggregated Home Network over the Home Link. a connected route to the Aggregated Home Network over the Home Link.
A Mobile Router returns Home by connecting directly to the Home Link, A Mobile Router returns Home by connecting directly to the Home Link,
and dropping the MRHA tunnel. The Mobile Router recognizes its Home and dropping the MRHA tunnel. The Mobile Router recognizes its Home
Link by a prefix match with its Home Agent. Link by a prefix match with its Home Agent.
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When a Mobile Router connects to the Home Link using its egress When a Mobile Router connects to the Home Link using its egress
interface, it might set up a bridge between its ingress interface(s) interface, it might set up a bridge between its ingress interface(s)
and the Home Link. and the Home Link.
Alternatively, the Mobile Router might perform ND proxying for all Alternatively, the Mobile Router might perform ND proxying for all
addresses in its MNPs, between the egress and the related ingress addresses in its MNPs, between the egress and the related ingress
interface. Since the prefixes on the egress and ingress interfaces interface. Since the prefixes on the egress and ingress interfaces
are overlapping, routing is disallowed. are overlapping, routing is disallowed.
On the positive side, the MR does not need to join the local IGP when On the positive side, the Mobile Router does not need to join the
returning Home, even if it is using the explicit Prefix Mode. When local IGP when returning Home, even if it is using the explicit
the MR is not registered, the HA simply expects that all MNNs will be Prefix Mode. When the Mobile Router is not registered, the Home
reachable over the Home Link. Agent simply expects that all MNNs will be reachable over the Home
Link.
HA HA
| /56 Aggreg /56 | /56 Aggreg /56
--+-----+--+- . -+- . -+-- --+-----+--+- . -+- . -+--
| | | | | | | |
MR1 MR2 MRi MRN MR1 MR2 MRi MRN
------ ------ ------ ------ ------ ------ ------ ------
/64 /64 /64 /64 Aggreg|i /64 0 < i <= N /64 /64 /64 /64 Aggreg|i /64 0 < i <= N
Figure 3: Bridging between egress and ingress Figure 3: Bridging between egress and ingress
6.2.2 Returning Home by ingress 6.2.2 Returning Home by ingress
Alternatively, if the MR has a single ingress Interface, the Mobile Alternatively, if the Mobile Router has a single ingress Interface,
Router may use the NEMO-Link to connect to the Home Link, merging the the Mobile Router may use the NEMO-Link to connect to the Home Link,
two links in a single consistent network. merging the two links in a single consistent network.
HA HA
| /56 Aggreg /56 | /56 Aggreg /56
--+-----+--+- . -+- . -+-- --+-----+--+- . -+- . -+--
/64 /64 /64 /64 Aggreg|i /64 0 < i <= N /64 /64 /64 /64 Aggreg|i /64 0 < i <= N
------ ------ ------ ------ ------ ------ ------ ------
MR1 MR2 MRi MRN MR1 MR2 MRi MRN
| | | | | | | |
Figure 4: Merging the Home and the Mobile Networks Figure 4: Merging the Home and the Mobile Networks
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sense for a Mobile Router to register using a Home Address from one sense for a Mobile Router to register using a Home Address from one
of its own MNPs. . of its own MNPs. .
6.3 Applicability 6.3 Applicability
With this model, there is no specific space for independent nodes as With this model, there is no specific space for independent nodes as
any address in the aggregation belongs to a MNP, and thus to a Mobile any address in the aggregation belongs to a MNP, and thus to a Mobile
Router. This configuration excludes the cohabitation with MIP6 MNs Router. This configuration excludes the cohabitation with MIP6 MNs
on the Home Link. on the Home Link.
A MR that is at Home must own an address from the aggregation on its A Mobile Router that is at Home must own an address from the
egress interface and an address from its MNP -a subnet of that aggregation on its egress interface and an address from its MNP -a
aggregation- on its ingress interface. A pure router will reject subnet of that aggregation- on its ingress interface. A pure router
that configuration, and the MR needs to act as a bridge to enable it. will reject that configuration, and the Mobile Router needs to act as
In order to deploy the aggregated Home Network model, one must check a bridge to enable it. In order to deploy the aggregated Home
whether that support is available in the MRs if returning Home is Network model, one must check whether that support is available in
required. the Mobile Routers if returning Home is required.
6.4 Deployment Caveats 6.4 Deployment Caveats
6.4.1 HA Side 6.4.1 Home Agent Side
A node on the Home Link discovers that the Aggregated Home Network is A node on the Home Link discovers that the Aggregated Home Network is
actually a subnet on the Home Link and may use the prefix on the Home actually a subnet on the Home Link and may use the prefix on the Home
Link to autoconfigure a Home Address. Such a node may also install a Link to autoconfigure a Home Address. Such a node may also install a
connected route to the Aggregated Home Network over the Home Link. connected route to the Aggregated Home Network over the Home Link.
As a result, unless the node has a better (longest match) route to a As a result, unless the node has a better (longest match) route to a
given Mobile Network Prefix, it will lookup all MNNs on that MNP given Mobile Network Prefix, it will lookup all MNNs on that MNP
using Neighbor Discovery over the Home Link. using Neighbor Discovery over the Home Link.
Thus, on the Home Link, the Home Agent MUST intercept all the packets Thus, on the Home Link, the Home Agent must intercept all the packets
to ALL the Mobile Network Nodes on the registered prefixes. In order to ALL the Mobile Network Nodes on the registered prefixes. In order
to do so, the Home Agent might perform some form of ND proxying for to do so, the Home Agent might perform some form of ND proxying for
all addresses in all registered Mobile Network Prefixes. The HA must all addresses in all registered Mobile Network Prefixes. The Home
also protect the MNP space from autoconfiguration by uncontrolled Agent must also protect the MNP space from autoconfiguration by
visitors at Neighbor Discovery level. uncontrolled visitors at Neighbor Discovery level.
Alternatives based on a routing protocol or ICMP redirect may apply Alternatives based on a routing protocol or ICMP redirect may apply
in some cases. in some cases.
In any case, there is a need to provide a specific configuration on In any case, there is a need to provide a specific configuration on
the HA to specify that it operates in Aggregated Mode. If a HA the Home Agent to specify that it operates in Aggregated Mode. If a
implementation is simply derived from that of MIP, then the Home Agent implementation is simply derived from that of MIP, then
capability to perform the required proxying might not exist, and the the capability to perform the required proxying might not exist, and
Aggregated Mode will not operate properly for nodes on the Home Link. the Aggregated Mode will not operate properly for nodes on the Home
Link.
6.4.2 MR side 6.4.2 Mobile Router side
If the MR returns Home by egress, a specific support is required to If the Mobile Router returns Home by egress, a specific support is
control the bridging operation depending on whether a MR is at Home required to control the bridging operation depending on whether a
or not. This support might not be present in all implementations. Mobile Router is at Home or not. This support might not be present
in all implementations.
Also, note that NEMO authorizes multiple registrations for a same MNP Also, note that NEMO authorizes multiple registrations for a same MNP
by different Mobile Routers. This is a case of multihoming, and it by different Mobile Routers. This is a case of multihoming, and it
normally means that the MRs are interconnected by the ingress network normally means that the Mobile Routers are interconnected by the
that bears the common MNP. But there is no provision in NEMO basic ingress network that bears the common MNP. But there is no provision
support to test that this condition is met at binding time and in NEMO basic support to test that this condition is met at binding
maintained overtime. time and maintained overtime.
It is thus possible for 2 different MRs to register a same prefix It is thus possible for 2 different Mobile Routers to register a same
with different Home Addresses, and this will cause an undetected prefix with different Home Addresses, and this will cause an
problem if the corresponding ingress links are not connected. undetected problem if the corresponding ingress links are not
connected.
When the Home Address of a Mobile Router is derived from its MNP, When the Home Address of a Mobile Router is derived from its MNP,
there is thus an additional risk of an undetected misconfiguration if there is thus an additional risk of an undetected misconfiguration if
the Home Address is autoconfigured from the ingress link as opposed the Home Address is autoconfigured from the ingress link as opposed
to statically assigned with the MNP itself. to statically assigned with the MNP itself.
7. Virtual Home Network 7. Virtual Home Network
7.1 Configuration 7.1 Configuration
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MR1 MR2 MRi MRN MR1 MR2 MRi MRN
/64 /64 /64 /64 A:B:C:i::/64 0 < i <= N /64 /64 /64 /64 A:B:C:i::/64 0 < i <= N
Figure 5: Virtual Home Network Figure 5: Virtual Home Network
The Extended Home Network and the Aggregated Home Network models can The Extended Home Network and the Aggregated Home Network models can
be adapted for virtual links. be adapted for virtual links.
As in the case of a physical link, the Home Address of a Mobile As in the case of a physical link, the Home Address of a Mobile
router can be constructed based on a dedicated subnet of the Home router can be constructed based on a dedicated subnet of the Home
Prefix or one of the MR MNPs. Prefix or one of the Mobile Router MNPs.
Note that since the Home Address is never checked for DAD, it makes Note that since the Home Address is never checked for DAD, it makes
the configuration easier to take it from the MNP as opposed to a the configuration easier to take it from the MNP as opposed to a
specific subnet. specific subnet.
There are certain advantages to making the Home Link a virtual link: There are certain advantages to making the Home Link a virtual link:
A virtual link may not experience any disruption related to A virtual link may not experience any disruption related to
physical maintenance or to hardware problems, so it is more physical maintenance or to hardware problems, so it is more
available than a physical link. The high availability of the Home available than a physical link. The high availability of the Home
skipping to change at page 16, line 17 skipping to change at page 16, line 17
the Home Agent. The Mobile Router, after connecting to the access the Home Agent. The Mobile Router, after connecting to the access
link, SHOULD not send any routing protocol updates on the egress link, SHOULD not send any routing protocol updates on the egress
interface because the routing information from the Mobile Router interface because the routing information from the Mobile Router
might adversely affect IPv6 route aggregation on the Home Network. might adversely affect IPv6 route aggregation on the Home Network.
However, the Mobile Router must register its binding as if it was However, the Mobile Router must register its binding as if it was
accessing a foreign link. accessing a foreign link.
There are also some drawbacks to the virtual Home Link approach: There are also some drawbacks to the virtual Home Link approach:
There can be only one Home Agent since Mobile IPv6 relies on There can be only one Home Agent since Mobile IPv6 relies on
Neighbor Discovery on the Home Link for other HA discovery and for Neighbor Discovery on the Home Link for other Home Agent discovery
Duplicate Address Detection. and for Duplicate Address Detection.
The Home Agent must maintain a Binding Cache entry for a Mobile The Home Agent must maintain a Binding Cache entry for a Mobile
Router and forwarding state for its Mobile Network even when the Router and forwarding state for its Mobile Network even when the
Mobile Router is directly connected to it. All traffic to and Mobile Router is directly connected to it. All traffic to and
from the Mobile Network is sent through the bi-directional tunnel from the Mobile Network is sent through the bi-directional tunnel
regardless of the Mobile Router location. This results in a regardless of the Mobile Router location. This results in a
tunneling overhead even though the Mobile Router is connected to tunneling overhead even though the Mobile Router is connected to
the Home Network. the Home Network.
Some solutions can be proposed in order to perform an equivalent of Some solutions can be proposed in order to perform an equivalent of
returning Home on a virtual Home Network. One such approach is returning Home on a virtual Home Network. One such approach is
sketched in appendix as an illustration. sketched in appendix as an illustration.
7.2 Applicability 7.2 Applicability
At some point in the future, NEMO basic support may be extended to At some point in the future, NEMO basic support may be extended to
operate fully at L3 for instance if the HAHA protocol [11] gets operate fully at L3 for instance if the HAHA protocol [11] gets
standardized and deployed. Until then, NEMO operations still inherit standardized and deployed. Until then, NEMO operations still inherit
from mobile IPv6 [7] for the HA to HA communication, which is from mobile IPv6 [7] for the Home Agent to Home Agent communication,
basically based on Neighbor Discovery extensions over the Home Link. which is basically based on Neighbor Discovery extensions over the
Making that link virtual bars the deployment of multiple Home Agents, Home Link. Making that link virtual bars the deployment of multiple
which may be desirable for reasons of load balancing. Please refer Home Agents, which may be desirable for reasons of load balancing.
to the NEMO multihoming issues [12] draft for more on this. Please refer to the NEMO multihoming issues [12] draft for more on
this.
Yet, for a deployment where a single HA is enough, making the Home Yet, for a deployment where a single Home Agent is enough, making the
Link virtual reduces the vulnerability to some attacks and to some Home Link virtual reduces the vulnerability to some attacks and to
hardware failures, while making the HA operation faster. some hardware failures, while making the Home Agent operation faster.
One should check with the product specifications of an HA to see One should check with the product specifications of an Home Agent to
whether the implementation actually supports a Virtual Home Network, see whether the implementation actually supports a Virtual Home
and if so, whether in that cases, it is optimized for faster DAD-less Network, and if so, whether in that cases, it is optimized for faster
bindings. DAD-less bindings.
8. Mobile Home 8. Mobile Home
8.1 Configuration 8.1 Configuration
In this disposition, there is a bitwise hierarchy of Home Networks. In this disposition, there is a bitwise hierarchy of Home Networks.
A global Home Network is advertised to the infrastructure by a head A global Home Network is advertised to the infrastructure by a head
Home Agent(s) and further subnetted into Mobile Networks. As a Home Agent(s) and further subnetted into Mobile Networks. As a
result, only the Home Agent(s) responsible for the most global result, only the Home Agent(s) responsible for the most global
(shortest prefix) aggregation receive all the packets for all the (shortest prefix) aggregation receive all the packets for all the
MNPs, which are leaves in the hierarchy tree. MNPs, which are leaves in the hierarchy tree.
Each subnet is owned by a Mobile Router that registers it in a NEMO Each subnet is owned by a Mobile Router that registers it in a NEMO
fashion while acting as a Home Agent for that network. This Mobile fashion while acting as a Home Agent for that network. This Mobile
Router is at Home at the upper level of hierarchy. This Router is at Home at the upper level of hierarchy. This
configuration is referred to as Mobile Home. configuration is referred to as Mobile Home.
An example of that is the Cab Co configuration. Say a Taxi Company An example of that is the Cab Co configuration. When a Taxi Company
owns a /32 prefix. This prefix is advertised at a fixed point, the owns a /32 prefix, this prefix is advertised at a fixed point in the
Headquarters say. Regional offices are deployed around the world. Head Quarters. Regional offices are deployed around the world. Even
Even though these regional offices are relatively stable in terms of though these regional offices are relatively stable in terms of
location and prefix requirement -say this changes every few years- location and prefix requirement -say this changes every few years-
making them mobile allows a simpler management when a move has to making them mobile allows a simpler management when a move has to
take place, or should the ISP service change. take place, or should the ISP service change.
global Home Network CAB:C0::/32 owned by HQ global Home Network CAB:C0::/32 owned by HQ
<-------------------------------------------------------------------> <------------------------------------------------------------------->
HQ extended Home Net Mobile Home for SFO office HQ extended Home Net Mobile Home for SFO office
(casa) (casa)
CAB:C0:CA5A::/48 CAB:C0:5F0::/48 CAB:C0:CA5A::/48 CAB:C0:5F0::/48
skipping to change at page 18, line 32 skipping to change at page 18, line 32
Figure 7: CAB Company regional configuration Figure 7: CAB Company regional configuration
Note that the hierarchy occurs at a configuration level and may not Note that the hierarchy occurs at a configuration level and may not
be reflected in the actual connection between nodes. For instance in be reflected in the actual connection between nodes. For instance in
the Cab Co case, cabs are roaming within the city, each one attaching the Cab Co case, cabs are roaming within the city, each one attaching
to a different hot spot, while the regional office is connected to to a different hot spot, while the regional office is connected to
the infrastructure using some ISP connection. the infrastructure using some ISP connection.
But it is also possible to reflect the organizational hierarchy in a But it is also possible to reflect the organizational hierarchy in a
moving cloud of Mobile Router. If a Mobile Home Agent acts as moving cloud of Mobile Router. If a Mobile Home Agent acts as
root-MR for a nested configuration of its own MRs, then the root-MR for a nested configuration of its own Mobile Routers, then
communication between MRs is confined within the nested structure. the communication between Mobile Routers is confined within the
nested structure.
This can be illustrated in the case of a fleet at sea. Say that now This can be illustrated in the case of a fleet at sea. Assuming that
SFO is a communication ship of a fleet, using a satellite link to SFO is a communication ship of a fleet, using a satellite link to
join the infrastructure, and that the cabs are Mobile Routers join the infrastructure, and that the cabs are Mobile Routers
installed on smaller ships, equipped with low range radios. installed on smaller ships, equipped with low range radios.
If SFO is also the root-MR of a nested structure of cabs, the If SFO is also the root-MR of a nested structure of cabs, the
communication between cabs is relayed by SFO and does not require the communication between cabs is relayed by SFO and does not require the
satellite link. SFO recursively terminates the nested tunnels to the satellite link. SFO recursively terminates the nested tunnels to the
cabs and reencapsulates all the packets between the nested cloud and cabs and reencapsulates all the packets between the nested cloud and
correspondents in the infrastructure in a single tunnel to CA5A, this correspondents in the infrastructure in a single tunnel to CA5A, this
providing for nested NEMO Route Optimization. providing for nested NEMO Route Optimization.
8.2 Applicability 8.2 Applicability
This complex topology applies to large distributed fleet, mostly if This complex topology applies to large distributed fleet, mostly if
there is a single interchange point with the internet (e.g. a NAT or there is a single interchange point with the internet (e.g. a NAT or
a socks farm) where the super HA could be located. a socks farm) where the super Home Agent could be located.
One specific benefit is that when 2 MRs travel together with a common One specific benefit is that when 2 Mobile Routers travel together
HA, the traffic between the 2 is not necessarily routed via the with a common Home Agent, the traffic between the 2 is not
infrastructure, but can stay confined within the mobile cloud, the necessarily routed via the infrastructure, but can stay confined
Mobile Home Agent acting as a rendez-vous point between the MRs. within the mobile cloud, the Mobile Home Agent acting as a
This applies particularly well for a fleet at sea when the long haul rendez-vous point between the Mobile Routers. This applies
access may be as expensive as a satellite link. particularly well for a fleet at sea when the long haul access may be
as expensive as a satellite link.
9. Changes 9. Changes
An issue list is maintained at
http://www.mobilenetworks.org/~pthubert/draft-ietf-nemo-home-network-models-issues.html .
9.1 Changes from version 00 to 01 9.1 Changes from version 00 to 01
Removed terminology (moved to the Nemo terminology draft). Removed terminology (moved to the Nemo terminology draft).
Added an applicability statement for all documented cases Added an applicability statement for all documented cases
9.2 Changes from version 01 to 02 9.2 Changes from version 01 to 02
Issue 1: Editorial Issue 1: Editorial
Issue 2: Added a caveat part in extended and aggregated sections. Issue 2: Added a caveat part in extended and aggregated sections.
Also added a MIP Home Network section prior to those. Also added a MIP Home Network section prior to those.
Issue 4: Added a subsection to the extended case for the case when Issue 4: Added a subsection to the extended case for the case when
the mr takes a home address from its MNP the mr takes a home address from its MNP
9.3 Changes from version 02 to 03
Issue 5: Editorial fixes.
10. Acknowledgements 10. Acknowledgements
The authors wish to thank: The authors wish to thank:
Erik Nordmark, Kent Leung, Thierry Ernst, TJ Kniveton, Patrick Erik Nordmark, Kent Leung, Thierry Ernst, TJ Kniveton, Patrick
Wetterwald, Alexandru Petrescu and David Binet. for their Wetterwald, Alexandru Petrescu and David Binet. for their
contributions. contributions.
11 References 11 References
skipping to change at page 21, line 41 skipping to change at page 21, line 41
3753, June 2004. 3753, June 2004.
[7] Johnson, D., Perkins, C. and J. Arkko, "Mobility Support in [7] Johnson, D., Perkins, C. and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004. IPv6", RFC 3775, June 2004.
[8] Devarapalli, V., Wakikawa, R., Petrescu, A. and P. Thubert, [8] Devarapalli, V., Wakikawa, R., Petrescu, A. and P. Thubert,
"Network Mobility (NEMO) Basic Support Protocol", RFC 3963, "Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
January 2005. January 2005.
[9] Ernst, T. and H. Lach, "Network Mobility Support Terminology", [9] Ernst, T. and H. Lach, "Network Mobility Support Terminology",
draft-ietf-nemo-terminology-02 (work in progress), October draft-ietf-nemo-terminology-03 (work in progress), February
2004. 2005.
[10] Ernst, T., "Network Mobility Support Goals and Requirements", [10] Ernst, T., "Network Mobility Support Goals and Requirements",
draft-ietf-nemo-requirements-03 (work in progress), October draft-ietf-nemo-requirements-04 (work in progress), February
2004. 2005.
[11] Thubert, P., "Global HA to HA protocol", [11] Thubert, P., "Global HA to HA protocol",
draft-thubert-nemo-global-haha-00 (work in progress), October draft-thubert-nemo-global-haha-00 (work in progress), October
2004. 2004.
[12] Ernst, T., "Analysis of Multihoming in Network Mobility [12] Ernst, T., "Analysis of Multihoming in Network Mobility
Support", draft-ietf-nemo-multihoming-issues-01 (work in Support", draft-ietf-nemo-multihoming-issues-02 (work in
progress), October 2004. progress), February 2005.
Authors' Addresses Authors' Addresses
Pascal Thubert Pascal Thubert
Cisco Systems Cisco Systems
Village d'Entreprises Green Side Village d'Entreprises Green Side
400, Avenue de Roumanille 400, Avenue de Roumanille
Batiment T3 Batiment T3
Biot - Sophia Antipolis 06410 Biot - Sophia Antipolis 06410
FRANCE FRANCE
skipping to change at page 23, line 25 skipping to change at page 23, line 25
associated with the virtual Home Link and considered as part of Home. associated with the virtual Home Link and considered as part of Home.
When accessing one of its virtual Home Access Links, a Mobile Router When accessing one of its virtual Home Access Links, a Mobile Router
autoconfigures a Care-of Address from a Router Advertisement as it autoconfigures a Care-of Address from a Router Advertisement as it
would do on any visited link, in order to perform the next binding would do on any visited link, in order to perform the next binding
flow. flow.
If the Mobile Router is configured to recognize the virtual Home If the Mobile Router is configured to recognize the virtual Home
Access Links as part of Home, it deregisters by sending a Binding Access Links as part of Home, it deregisters by sending a Binding
update with null lifetime sourced at the CareOf. Alternatively, the update with null lifetime sourced at the CareOf. Alternatively, the
Home Agent may indicate that the MR has moved to the virtual Home Home Agent may indicate that the Mobile Router has moved to the
Access Links as a status code in the binding acknowledgement. The virtual Home Access Links as a status code in the binding
status code implies that Home Agent successsful de-register the acknowledgement. The status code implies that Home Agent successsful
binding at the virtual Home Access Link. Detection of the virtual de-register the binding at the virtual Home Access Link. Detection
Home Access Links is achieved by a prefix comparison(s) between the of the virtual Home Access Links is achieved by a prefix
care-of address and the prefix(es) on the virtual Home Access comparison(s) between the care-of address and the prefix(es) on the
Link(s). virtual Home Access Link(s).
With both approaches, the result of the binding flow is a With both approaches, the result of the binding flow is a
deregistration. Consequently, both the Mobile Router and the Home deregistration. Consequently, both the Mobile Router and the Home
Agent disable the bi-directional tunnel. At that point, the Home Agent disable the bi-directional tunnel. At that point, the Home
Agent configures its forwarding in order to reach the Mobile Router Agent configures its forwarding in order to reach the Mobile Router
and its mobile networks at Home. For instance, this may take the and its mobile networks at Home. For instance, this may take the
form of a route to the Mobile Network prefixes via the MR Home form of a route to the Mobile Network prefixes via the Mobile Router
Address, and a connected host route to the MR Home Address via the Home Address, and a connected host route to the Mobile Router's Home
virtual Home Access link. Address via the virtual Home Access link.
After successful binding de-registration, the Mobile Router MUST After successful binding de-registration, the Mobile Router must
receive packets meant to the Mobile Router's Home Address at the receive packets meant to the Mobile Router's Home Address at the
Virtual Home Link. How to intercept packets addressed to the Home Virtual Home Link. How to intercept packets addressed to the Home
Address depends on implementations of the Mobile Router. If the Home Address depends on implementations of the Mobile Router. If the Home
Address is not configured at the egress interface, the Mobile Router Address is not configured at the egress interface, the Mobile Router
MUST use proxy Neighbor Discovery to intercept all packets addressed must use proxy Neighbor Discovery to intercept all packets addressed
to the Home Address on the virtual Home Link. Otherwise, the Mobile to the Home Address on the virtual Home Link. Otherwise, the Mobile
Router does not have to perform any special operation at the virtual Router does not have to perform any special operation at the virtual
Home Link. Home Link.
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
 End of changes. 

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