About LSAM Relocation : Model

Motivation to Relocate

Information consumers are becoming increasingly mobile, but need to continue to access distributed information efficiently.

Scientific researchers in the field need access to their research materials
Disaster relief teams at the scene of an emergency need information about the site and other related information
Tele-commuters need access to the same information at home as at the office

LSAM enables the relocation of people and teams by making the proxies used by them relocatable. LSAM does not support fast cell hand-off style relocation, as underlying transport should be able to keep clients in close contact with their proxy if they stay close. LSAM relocates proxies to support long term or long distance moves here transport roaming support is inefficient.

Proxies can move geographically
Proxies can change request routing hierarchies
A relocated proxy retains its cache state and multicast channel selections

Method of Relocation

To relocate a proxy:

The proxy informs LSAM where it wishes to move, e.g, to Washington D. C.
LSAM selects candidate hosts in the geographic area that the proxy suggested and informs the relocating proxy
The relocating proxy informs any clients where to find the relocated proxy
Clients disconnect
Candidate hosts transfer the relocating proxy's state
Relocating proxy shuts down
Clients appear at new site and select among relocated candidates.
Unselected candidates shut down

Why Move Proxies in the Network?

Moving the proxy independently of the team of clients :

Allows the proxy system to manage network load by moving proxy state when it is efficient to do so
Allows the relocated proxy to continue pre-loading caches on clients' behalf