HAWAII final

8/7/2019 HAWAII final

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HAWAII: A Domain-based Approach

Mobile IP is the current standard for supportingmacro-mobility in IP networks.

Most user mobility is local to a domain.

In HAWAII (Handoff-Aware Wireless AccessInternet Infrastructure), mobile hosts retain theirnetwork address while moving within a domain.

Uses specialized path setup schemes which install

host-based forwarding entries in specific routers tohandle intra-domain micro-mobility.

Defaults to using mobile IP for inter-domainmacro-mobility.


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Design Goals

We have five design goals in HAWAII:

Limit disruption to user traffic.

Enable efficient use of access network resources.

Enhance scalability.

Provide intrinsic support for QoS.

Enhance reliability.


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Related Work(1/2)

The vast majority of prior work has focused on limitingthe disruption to user traffic during handoff.

One common approach, proposed originally forATM-based networks, is extending connections from theprevious base station.

The goals of scalability and QoS can be easily achieved.

Another extension approach was Mobile-IP ROproposal.

A change in mobile hosts IP care-of address duringhandoff requires updates to the home agent, that thenintroduces scalability and QoS concerns.


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Related work (2/2)

Another common approach for reducing disruption is

through the use ofmulticasting.

Loss of efficiency due to wasted bandwidth.

Impact scalability in the backbone routers where every

mobile hosts multicast address needs to be managed.

The recent Cellular IP proposal uses specialized domain

routers with host-based entries for local mobility and the

use of Mobile-IP for inter-domain mobility. Cellular IPrelies on the gateway to act as a FA. Failure of the

Gateway FA can impact reliability.


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Protocol Overview(1/3)


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HAWAII segregating the network into a hierarchy ofdomains.

When the mobile host first enters into a foreigndomain, we revert to traditional Mobile IPmechanisms and the mobile host is assigned a co-located care-of address using DHCP.

If the foreign domain is also based on HAWAII, thenfor subsequent movements within the foreign domain,

the mobile host retains its care-of address unchanged.


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Message types

Power up (establish host-specific routes)

Update (establish and update host-specific

routes) Refresh

We characterize the HAWAII path state maintainedin the routers as soft-state.

path state is soft-state, MH sends periodic messagesto BS to maintain host-based entries, BS andintermediate routers send aggregate hop-by-hoprefresh messages towards domain root router


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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 thecrossover router.

Non-Forwarding Schemes Data packets are diverted at the crossover router to the

new base station, resulting in no forwarding of packetsfrom the old base station.

Crossover Router : the router closest to the mobile

host that is at the intersection of two paths, onebetween the domain root router and the old basestation, and the second between the old basestation and the new base station.


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Forwarding Schemes-MSF(1/3)

Multiple Stream Forwarding.

Message 1 contains the new base stations address.

Old BS lookup for new BSs routing table and adds a

forwarding entry for MHs IP. Router 0, the crossover router in this case, adds

forwarding entries that result in new packets beingdiverted to the MH at the new BS.

Message 6 is the ACK back to the MH.


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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 15 establish these entries resulting inpackets arriving at the old BS and being forwardedto the new BS as a single stream.

The old BS subsequently sends Message 6 toRouter 0 for diverting the stream at the crossoverrouter.

Message 7 is the ACK back to MH.

In order to achieve this without the use oftunneling, we use a technique we term interface-based forwarding. (incoming interface(s), IPaddress poutgoing 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 isoptimized for networks where the MH is able tolisten/transmit to only one base station.

Message 7 is ACK to MH. The MNF scheme is very similar to the UNF

scheme. The main difference is that the crossoverrouter, Router 0, multicasts data packets for a

short duration. This helps limit packet loss innetworks in which the mobile host can only listento a single BS.


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Non-Forwarding Schemes-MNF(2/2)


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Ifany linkorrouterfails


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Conclusion

HAWAII is a comprehensive solution for

micro-mobility support and seamlessly works

with Mobile IP in order to support wide-area

user mobility.

Documents

HAWAII final