Transcript Basic Operation of HMIPv6

HMIPv6
Mobile-IPv6
• Modes for communications between the
mobile node and a correspondent node
– Bidirectional tunneling
• Does not require Mobile IPv6 support from the
correspondent node
– “Route Optimization“
• Requires the mobile node to register its current
binding at the correspondent node.
• Packets from the correspondent node can be routed
directly to the care-of address of the mobile node
Mobile-IPv6 using Reverse Tunneling
Mobile Node
“ ”
Access Router
Access Router
Internet or Intranet
Corresponding Node
Home Agent
Mobile-IPv6 using Route Optimization
Mobile Node
“ ”
Access Router
Access Router
Internet or Intranet
Corresponding Node
Home Agent
Mobile-IPv6 Binding Updates
Binding
Updates
Mobile Node
“ ”
Access Router
Internet or Intranet
Corresponding Node
Home Agent
x
Access Router
Drawbacks of Mobile IPv6
• Mobile IPv6
– Reacts after L2 movement
– Introduces a period of service disruption after L2 movement
until signaling is completed
– Performance depends on Mobile IP registration time and MHHA distance
• Optimization Schemes
– Fast Handover for Mobile IPv6
• Anticipates Mobile IP messaging (before L2 movement)
– Hierarchical Mobile IPv6
• Reduces MN to HA round trip delay
• Reduces the number of messages (ratio transmission
efficiency)
11.2 Hierarchical Mobile IPv6 (HMIPv6) –
RFC4140
• HMIPv6 requires new entities called Mobility Anchor
Points (MAPs) in the visiting network.
• MAP acts as a local home agent.
• It is usually implemented on a router.
• Mobile nodes have to perform binding updates to home
agents and correspondent nodes only when it firstly
enters into a MAP domain.
• When mobile nodes move inside the MAP domain, they
do not have to perform binding updates to home agent
and correspondent nodes. Binding updates to the MAP
are only needed.
• If HMIPv6 is not provided in a visited network, a mobile
node performs normal MIPv6 protocol and gets
connectivity to Internet.
Figure 11-1. Hierarchical Mobile IPv6.
Figure 11-1. Hierarchical Mobile IPv6.
Two types of care-of address are
defined for HMIPv6
• on-link care-of address (LCoA) is a CoA used as a CoA
in the binding update to MAP.
• regional care-of address (RCoA) is a CoA in the binding
update to home agent and correspondent nodes in case
of route optimization.
• Only RCoA is registered at the mobile node's home
agent and correspondent nodes.
• MAPs keep binding between RCoA and LCoA
• home agents keep binding between mobile node's home
address and the primary care-of address (RCoA)
• Movements within MAP are not informed
to outer nodes of MAP.
• Only movements between MAPs are
notified to home agent, which reduces
mobile signaling message exchanges
between inner MAP domain and outer
network.
11.2.2 Terminology
• Access Router (AR): mobile node's default router.
• On-link care-of address (LCoA): LCoA is an address
obtained from the visited network via stateless address
configuration mechanism.
– Prefix information is learned from Router Advertisement
message from a default router, AR.
– In original MIPv6, this address type is simply called care-of
address.
• Mobility Anchor Point (MAP): MAP is a special router
located in a visited network by a mobile node.
– MAP operates as a local home agent.
– Multiple MAPs may exist in a visited network.
• MAP domain: MAP domain is determined by Router
Advertisement messages from access routers, which
contain MAP information.
11.2.2 Terminology
• Regional care-of address (RCoA): RCoA is an
address obtained from the visited network via
stateless address configuration mechanism.
– Prefix information is learned from MAP option of the
Router Advertisement message.
– Only this address type is known to domains outside of
MAP.
• Local Binding Update: Local Binding is modified
by the Binding Update message to MAP.
– Once MAP receives this message, it starts DAD for
RCoA because RCoA may be already occupied.
– If there is no conflict, it updates Binding Cache Entry
(BCE) for the binding between RCoA and LCoA of the
mobile node.
11.2.3 Operation
• when a mobile node enters MAP domain
• When a mobile node moves within
MAP domain
when a mobile node enters MAP domain
Router Advertisement and address
configuration
1. When a mobile node visits a network, the node will receive Router
Advertisement messages from AR(s).
– When HMIPv6 is supported in the visited network, the Advertisement
message will contain MAP option to allow the mobile to discover MAP
address.
– Available MAP list is kept in the AR and periodically sent using Router
Advertisement messages.
2. Once the mobile node receives Router Advertisement messages with
the MAP option which contains prefix information for RCoA, it will
configure two addresses, RCoA and LCoA by the stateless address
configuration mechanism.
– In detail, the mobile node learns a prefix for LCoA from Prefix
Information option
– a prefix for RCoA from MAP option in the Router Advertisement
message.
– Then, the mobile node builds RCoA and LCoA by appending 64-bit
prefix to 64-bit interface identifier.
MAP option
- 11.2.5.2 Neighbor Discovery extension
• MAP option is contained in the Option field of Router Advertisement
messages to allow mobile nodes to learn MAP address from ARs.
Figure 11-3. Router Advertisement message from access router at step 2 in Fig. 11-2.
Local Binding Update
Figure 11-4. Exchanged messages for MAP Registration at step 4 in Fig. 11-2.
Local Binding Update
3. As the mobile node builds RCoA, the mobile node sends
Local Binding Update message to the MAP.
– The A and M flags in the Local Binding Update message should
be set to differentiate from the original Binding Update message.
– In the Local Binding Update message to MAP, RCoA is regarded
as the home address for the mobile node and contained in the
Home Address option. Mobile node's LCoA is used as the source
address.
4. Upon MAP receives Local Binding Update
message, it binds mobile node's RCoA to its
LCoA. Simultaneously, the MAP performs DAD
for mobile node's RCoA.
5. The MAP will return a Binding
Acknowledgement message to the mobile node,
to indicate the result of the binding update to
MAP.
6. The mobile node must silently discard any
acknowledgement packet from MAP without
Type 2 Routing Header, which contains mobile
node's RCoA.
bidirectional tunnel
• Once the binding update to the MAP is
successfully completed, a bidirectional tunnel
between the mobile node and MAP is
established.
• Any communication between the mobile node
and correspondent nodes should go through the
MAP.
• The MAP will perform encapsulation for packets
from correspondent nodes or mobile node's
home agent to the mobile node
• and also perform decapsulating packets from
the mobile node to forward them to
correspondent nodes.
binding update to HA and CN
• Once the binding update to MAP is successfully completed, binding
updates to home agent and correspondent nodes should be
followed.
• These binding updates are same as specified in MIPv6 standard
except that RCoA is used as the care-of address.
• LCoA is unknown to outside of MAP domain.
• Thus, when HA and CNs sends packets to the mobile node, the
Destination Address field of packet should be set to the mobile
node's RCoA.
• MAP intercepts them and fetches LCoA corresponding to RCoA by
referring the binding cache table.
– Then, it tunnels packets to the mobile node.
– For the tunneling, the Destination Address field is filled with LCoA, and
Source Address field is filled with the address of MAP.
– Any delivered packet without Type 2 Routing Header will be discarded
in the mobile node.
Figure 11-5. Data packet exchange between a mobile node and correspondent node
at step 7 in Fig. 11-2.
层次移动IPv6信令消息交互图
a mobile node moves within
MAP domain
• If the mobile node changes its physical location
within MAP domain, only binding update to MAP
is required.
• Thus, the old LCoA in BCE will be replaced by a
new one.
• Binding updates to its home agent or
correspondent nodes are not necessary.
• The MAP domain is determined by Router
Advertisement messages from ARs.
• Since binding updates to home agent and
correspondent nodes are not required, the
binding update latency may be significantly
reduced.
Figure 11-6. HMIPv6 example2: when a mobile node moves into new AR within the same
MAP domain.
Figure 11-7. HMIPv6 Example 3: when a mobile node moves into new MAP domain.
Messages for home registration may not pass through MAP.
Hierarchical Mobile IPv6
Handoff Time
HMIPv6
• Motivation
– Reduce the number of Bus when MNs move within a MAP
domain
– Transparency of the MN’s mobility to CNs
– Location Privacy
• HMIPv6
– Mobility anchor point (MAP): Local HA
– MN acquires two addresses
• On-link CoA: LCoA
• Regional CoA: RCoA
– Reduce Mobile IPv6 signaling load
– Improve Handoff delay
Basic Operation of HMIPv6
Extension of MIPv6
– Minor extensions to MN operation
– CN and HA operation will not be affected
The introduction of the MAP concept
– Minimize the latency due to handoffs between AR
– Diminish signaling (including wireless resource) costs
MN only perform one local BU to a MAP when
changing its location within the MAP domain.
Local Location Transparency
– On-Link Address : LCoA,
Regional Care-of Address : RCoA
– If the MN changes its LCoA within a local MAP domain, it
only needs to register the new LCoA with the MAP.
– RCoA registered with CNs and the HA does not change.
– This makes the MN's mobility transparent to the CNs
HMIPv6 Operation
(Home address, RCoA)
HA
CN
Internet
Home BU
MAP (RCoA, LCoA)
MAP domain
Local BU
old
AR
MN
new
AR
MAP
HMIPv6 Operation
(Home address, RCoA)
HA
CN
Internet
MAP (RCoA, LCoA’)
MAP domain
old
AR
Local BU
new
AR
MN
MAP
HMIPv6 Operation
(Home address, RCoA’)
HA
CN
Internet
Home BU
MAP (RCoA’, LCoA’)
MAP
MAP domain
old
AR
new
AR
Local BU
MN
Basic Operation of HMIPv6
Basic Operation of HMIPv6
Basic Operation of HMIPv6
Basic Operation of HMIPv6
Dynamic MAP Discovery
nProcedure of Dynamic MAP Discovery
propagate the MAP option from the MAP to the MN
through the hierarchy of routers.
The routers receiving the MAP option propagate them
on certain interfaces with Router Advertisement
message
MAP Selection in a distributed-MAPs Environment
•Furthest MAP
– MN may choose to register with the furthest MAP to avoid
frequent re-registrations.
– This is particularly important for fast MNs that will perform
frequent handoffs.
•Nearest MAP
– Network operators may choose a flat architecture in some cases
where a MIP handoff may be considered a rare event.
– In these scenarios, operators may choose to include the MAP
function in the lowest ARs.
– In this scenario, a MN may choose a MAP (in the AR) as an
anchor point when performing a handoff.
– This kind of dynamic hierarchy (or anchoring) is only
recommended for cases where inter-AR movement is not frequent.