Transcript interface-based forwarding

HAWAIIHandoff-Aware Wireless Access
Internet Infrastructure
Reporter：Jing-Shiuan Hua
Date：2005/4/26
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Outline
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Introduction
Design Goals
Network Architecture
Path Setup Schemes
– Powerup
– Forwarding Schemes
– Nonforwarding Schemes
• Conclusion
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Introduction
• Mobile IP is the current standard for supporting
macro-mobility in IP networks.
• Most user mobility is local to a domain.
• In HAWAII (Handoff-Aware Wireless Access
Internet Infrastructure), mobile hosts retain their
network address while moving within a domain.
• Uses specialized path setup schemes which install
host-based forwarding entries in specific routers to
handle intra-domain micro-mobility.
• Defaults to using mobile IP for inter-domain
macro-mobility.
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Design Goals
• Limit disruption to user traffic.
• Enable efficient use of access network
resources.
• Enhance scalability
• Provide intrinsic support for QoS
• Simplify reliability
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Network Architecture (1/3)
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Network Architecture (2/3)
• HAWAII segregating the network into a hierarchy
of domains.
• When the mobile host first enters into a foreign
domain, we revert to traditional Mobile IP
mechanisms and the mobile host is assigned a colocated care-of address using DHCP.
• If the foreign domain is also based on HAWAII,
then for subsequent movements within the foreign
domain, the mobile host retains its care-of address
unchanged.
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Network Architecture (3/3)
• Message types
– Power up (establish host-specific routes)
– Update (establish and update host-specific
routes)
– Refresh
• We characterize the HAWAII path state maintained
in the routers as “soft-state”.
• path state is soft-state, MH sends periodic messages
to BS to maintain host-based entries, BS and
intermediate routers send aggregate hop-by-hop
refresh messages towards domain root router
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Path Setup Schemes-Power up(1/2)
• MH send path setup message to BS.
• BS adds a forwarding entry for the MH, and
forwards path setup message to next hop.
• Router 1 performs similar processing and forwards
the message to Router 0. (domain root router in
this example)
• Router 0 adds an entry for the mobile host, and
since it is the intended destination for the update
message, sends an acknowledgment back to the
mobile host.
• If the mobile host is in a foreign domain, it will
register its IP address with its home agent.
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Path Setup Schemes-Power up(2/2)
• Other routers in the domain have no knowledge of the
mobile host’s IP address.
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Path Setup Schemes
• Forwarding Schemes
– Packets are first forwarded from the old base station to
the new base station before they are diverted at the
crossover router.
• Non-Forwarding Schemes
– Data packets are diverted at the crossover router to the
new base station, resulting in no forwarding of packets
from the old base station.
Crossover Router : the router closest to the mobile
host that is at the intersection of two paths, one
between the domain root router and the old base
station, and the second between the old base
station and the new base station.
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Forwarding Schemes-MSF(1/3)
• Multiple Stream Forwarding.
• Message 1 contains the new base station’s
address.
• Old BS lookup for new BS’s routing table and
adds a forwarding entry for MH’s IP.
• Router 0, the crossover router in this case, adds
forwarding entries that result in new packets being
diverted to the MH at the new BS.
• Message 6 is the ACK back to the MH.
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Forwarding Schemes-MSF(2/3)
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Forwarding Schemes-MSF(3/3)
• Disadvantage
– Can lead to the creation of multiple streams of
misordered packets arriving at the MH.
– Can result in creation of transient routing loops.
• Advantage
– The main benefit of this scheme is that it is
simple and results in no loss.
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Forwarding Schemes-SSF(1/2)
• Single Stream Forwarding.
• Message 1–5 establish these entries resulting in
packets arriving at the old BS and being forwarded
to the new BS as a single stream.
• The old BS subsequently sends Message 6 to
Router 0 for diverting the stream at the crossover
router.
• Message 7 is the ACK back to MH.
• In order to achieve this without the use of
tunneling, we use a technique we term interfacebased forwarding. (incoming interface(s), IP
address  outgoing interface)
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Forwarding Schemes-SSF(2/2)
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Non-Forwarding Schemes-UNF(1/2)
• Unicast nonforwarding(UNF) scheme is
optimized for networks where the MH is
able to listen/transmit to two or more base
stations simultaneously for a short duration.
• Message 6 is ACK to the MH.
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Non-Forwarding Schemes-UNF(2/2)
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Non-Forwarding Schemes-MNF(1/2)
• The multicast non-forwarding (MNF)
scheme is optimized for networks where the
MH is able to listen/transmit to only one
base station.
• Message 7 is ACK to MH.
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Non-Forwarding Schemes-MNF(2/2)
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Non-Forwarding Schemes
UNF
MNF
• The MNF scheme is very similar to the UNF scheme.
The main difference is that the crossover router,
Router 0, multicasts data packets for a short duration.
This helps limit packet loss in networks in which the
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mobile host can only listen to a single BS.
Conclusion
• HAWAII is a comprehensive solution for
micro-mobility support and seamlessly
works with Mobile IP in order to support
wide-area user mobility.
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Reference
• R. Ramjee, et al., “HAWAII：A DomainBased Approach for Supporting Mobility in
Wide-Area Wireless Networks,”
IEEE/ACM Transaction on Networking,
June 2002.
• R. Ramjee, et al., “IP micro-mobility
support using HAWAII,” Internet draft.
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