An Always Best Connected Service

1
An Always Best Connected Service

• Sridhar Machiraju (machi_at_cs.berkeley.edu)
• Per Johansson (Per.Johansson_at_ericsson.com)

2
Motivation
Cingular Starts 3G Migration
Nokia Unveils Roaming Solution Using GSM, WLANs
Ericsson Takes Lead In GPRS Race
ATT Wireless Expands GPRS
Three airlines racing to provide public
high-speed wireless LAN service at gates
3
So

• Can wide area wireless operators leverage the
  proliferating use of high-speed local area
  networks and other wide area networks to augment
  their Always Connected Service to an Always Best
  Connected Service while preserving the seamless
  nature of connectivity.

4
How to Support Mobility?

• Mobility is known to require a level of
  indirection that is provided by Mobility servers
  (e.g. Home Agents, Session layer proxies etc).
  How do different mobility solutions compare in an
  ABCS scenario w.r.t scalability, robustness,
  security ?
• A device may use a single Mose or multiple Moses.
  How may this be achieved and what are the pros
  and cons of either approach?
• What are the placement issues to be considered by
  a Mobility service provider?

5
Why, When and How to Cooperate?

• By cooperating providers could increase the
  best part of ABCS, reduce operational costs.
  Disadvantages include the absence of
  differentiation between services offered by
  different operators, potential abuses.
• Use inter-provider handoff as a means of shedding
  load.
• Assuming its necessity, how may cooperation be
  realized? Some possible mechanisms include
  automated auctions or capacity clearing houses
  etc.

WAN Operator G
WLAN G1
WLAN M1
WLAN M2
WAN Operator R
WLAN R2
WLAN R1
Shed load in hot spot by handing off to G.
Provide connectivity in the office using R2 here.
Provide connectivity using M2 by cooperating with
the independent operator at the café.
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QoS and Security

• In an ABCS scenario, what should be the nature of
  QoS guarantees and how are they guaranteed.
• Since users would like to have a single provider
  (And consequently, a single bill) how are a
  providers users authenticated (in real-time)
  with other access providers while limiting the
  number of logons to be performed.
• As with any cooperative scenario, verification of
  the agreements of peers is an important
  requirement. How is this performed?

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A NAT-based Solution for ABCS Ongoing Work

• Traditional Mobile IP drawbacks -
• Traditional Mobile IP requires hosts to possess a
  fixed (home) IP address. This is unsuitable for
  wireless devices such as cellphones, PDAs.
• Triangle routing could result in high overhead
  since the active network interfaces list could
  change frequently.
• A possible solution
• All applications of a device use an internal IP
  address IPint.
• Each device runs a local NAT that replaces IPint
  with IPaik and tunnels it out of the active
  interface k to a Mose IPmose that is expected to
  be near the correspondent host. How it determines
  IPmose is an open question.
• The mose is a NAT that replaces IPaik with any
  available IP address IPfixed. and creates an
  (IPdest, IPfixed, IPaik) in a local table.

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Schematic of NAT-based Solution
Mobility Server
Application
IPint,IPdest
Tunnel Encap-sulation
Tunnel Decap-sulation
PureNAT
NAT
IPaik, IPmose (IPaik,IPdest)
IPfixed,IPdest
IPaik,IPdest
IPaik,IPdest
NAT Table
Mobile Host (MH)
Correspondent Host (CH)
IPaik, IPfixed, IPdest
CH
It is important that the mobility servers
(which is dependent on the correspondent host) be
as near the correspondent host as possible in
order to reduce the inefficiency that could occur
due to triangular routing.
Mose
CH
CH
CH
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A Comparison of Different Mobility Solutions