Re: Elements of a DMM Solution

Hi, Georgios,

Essentially, yes.  And we can talk separately about the solution
for each module.  And different operators might make different
choices for which solution(s) to deploy in their network.

-Pete

[email protected] wrote:
> Hi Peter,
> 
> 
> 
> I agree with the main message of your email, which I am translating into:
> 
> 
> 
> *) Define protocol agnostic Functional Framework to build DMM
> solutions around existing mobility protocols:
>    o) can apply to solutions that are solely based on existing IP
>    mobility protocols 
>    o) can apply to solutions which get support from
>    non mobility protocols
> 
> 
> 
> Best regards,
> 
> Georgios
> 
> ________________________________
> 
> Van: [email protected] [[email protected]] namens Peter McCann
> [[email protected]] Verzonden: dinsdag 30 juli 2013 13:09 To:
> [email protected] Onderwerp: [DMM] Elements of a DMM Solution
> 
> 
> I think that the DMM work can be subdivided into a small number of
> "modules", each of which can be implemented in a number of different
> ways.
> 
> 
> I. Limited-scope (localized) network-based mobility scheme
> 
> This is probably what most people have in mind when they think of a
> DMM "protocol".  This is the mechanism that gets packets to the
> current point of attachment.  We have seen the following proposed as
> options for this
> module:
> 
>    A. Something based on PMIP
>    B. Something based on GTP
>    C. Something based on a routing protocol (e.g., BGP)
>    D. Something based on SDN
> We should be able to "plug in" any of the above solutions to an
> overall DMM framework.  This module needs to be signaled when an MN
> attaches or changes its point of attachment.  An identifier of the MN
> and an identifier of the attachment point should be provided in this signal.
> This module needs to interact with the address allocation/management
> module to obtain the set of IP prefixes currently in use by the mobile
> node, so that redirection/tunneling of packets destined to those
> prefixes can be set up.  This may require a network-queryable database
> of prefixes that can be indexed by mobile node identifier.  This
> database could be stored in something like an HSS or in a DNS server.
> 
> 
> II. Address allocation/management
> 
> This module lives in both the MN and the network.  The MN maintains a
> pool of addresses, each one topologically related to the point of
> attachment at the time it was assigned.  The MN should be made aware
> of which of its addresses are currently on-link at its current
> attachment point, courtesy of Module I.  The MN should maintain
> information about how it is using each address so that unused
> addresses can be released and in-use addresses can have their leases
> renewed at the appropriate times.  Address allocation/deallocation
> should NOT be coupled to node mobility.  It should be possible to have
> a mobility event without allocating a new address (to avoid excessive
> numbers of addresses being
> allocated) and even if Module I cannot provide network-based
> relocation of a prefix, mobility to an attachment point where an
> address is not on-link SHOULD NOT trigger deallocation of the address,
> because the MN might have a client-based mobility scheme that enables
> it to continue using the address (Module III).  Some mechanism to
> renew the lease on the address from a remote location should be
> provided, such as obtaining a global unicast IP address of a DHCP
> server.  Security considerations for such remote renewal need to be
> investigated and addressed.
> 
> Module I must be provided with a list of prefixes currently allocated
> to the MN.
> The database storing this information could be updated by the network
> element that allocates the address (e.g., DHCP server) or could be
> updated by the MN.  A network element initiated update may be more
> appropriate for an HSS-stored database, whereas an MN-initiated update
> may be more appropriate for a DNS-based database.
> 
> 
> III. An optional global, client-based mobility scheme
> 
> Any network-based mobility scheme will necessarily have a limited
> scope.  This is especially true in the DMM case because the Internet
> attachment points are by definition close to the MN in the access
> (visited) network.  Consider a roaming mobile node with home network H
> that attaches to visited network V1.
> It obtains DMM service from V1, obtaining an IP address topologically
> routed from the Internet directly to V1.  Now consider this MN
> performing a handoff from V1 to another visited network V2.  V2 has a
> roaming agreement with H (otherwise the MN would not be able to get
> service) but has absolutely no business arrangement with V1.
> Therefore, it is impossible for the network-based mobility scheme to
> support re-routing or tunneling the packets destined to the original
> V1 address to network V2.  We must therefore support fall-back to a
> client-based OTT global mobility scheme, using the fact that both V1
> and V2 offer connectivity to the same Internet, if the MN wants to
> keep using the address it got while connected to V1.
> 
> Allocation of a global mobility anchor should be coupled to allocation
> of the address for which global mobility is needed.  There are already
> DHCP extensions to carry HA IP addresses which could be used for this
> purpose.  The MN-HA security association should also be bootstrapped
> at this time, so that the establishment of security does not add
> latency at the time the global mobility service is invoked.  We need
> to investigate whether the current DHCP extension provides the right
> kind of HA identifier to the MN or whether a DNS name would be more
> helpful in bootstrapping security.
> 
> The global mobility anchor may invoke Module I to get the
> HoA-addressed packets delivered to itself before tunneling them to the
> MN's CoA.  The MN should make use of Module I for its CoA in its new
> visited network to minimize the number of global mobility location
> update messages it needs to send to the anchor point.
> 
> 
> IV. Security
> 
> Module I depends on a secure network access control protocol to
> provide an authenticated MN identity.  Similarly, Module III requires
> bootstrapping a security association between MN and HA.  So far, the
> AAA suite of protocols have been used for this purpose.  However, it
> may be possible to further optimize this process and unify the
> credentials used by the various nodes if new solutions are
> investigated.  Eliminating the round-trip to the home AAA server would
> dramatically improve the performance of network attachment and MN-HA
> SA establishment.  Making use of DNS-based public key credentials that
> can be locally cached may allow the elimination of this round-trip and
> improve the scalability of home network infrastructure.
> 
> These enhancements to security can be decoupled from the rest of the
> architecture and investigated separately.
> 
> 
> 
> 
> I think it's important for the DMM working group to investigate all 4
> of the above solution components, even though most people in the group
> are probably focused on Module I for now.  We need to understand how
> the pieces will fit together into an overall system.  To the extent we
> need to make changes to MN implementation practices, we should publish
> advice in Informational RFCs.
> To the extent we need to modify protocols that are outside the scope
> of DMM, we should send requirements to other working groups and
> encourage the work to get done.
> 
>