Self-Configuration and Administration of Wireless Grids - Cloud, Grid and High Performance Computing: Emerging Applications - page 267

VOs will require the protocol to enable dynamic
access to multiples AOs with each VO.

to the new RS. BS will update its list of RSs and
send the VO information back to the RS.

BS Entry or Exit BS

It is possible that two or more BS discover one
another. In that case, they will send broadcast mes-
sages describing their VO. Each BS will receive an
acknowledgement in response and the information
about other BS. Through such interactions each
BS will be able to generate a list of existing VOs
and the names and addresses of the associated BSs.
A BS will broadcast its entry or exit. Remaining
BSs will update their lists accordingly.

In case of multiple BSs within a VO, the entry of
a new BS will be broadcasted to all the existing
BSs. In response, the BSs will send their informa-
tion to the new BS. This will include information
about their AOs. For the node discovery, a BS will
first check with the BSs within the VO before
forwarding the request across multiple VOs.

Addressing Transient
Nature of Wireless Grid

Multiple RS and BS

Wireless networks are characterized by weak
transmission signals and message losses. Power
constrained nodes may suddenly crash. These
types of events can create inconsistencies in the
information maintained by the grid components
Node Failure: In order to detect the node fail-
ure, the RS can periodically send hello requests to
the registered nodes. In case of no response from
the node, the RS will send the hello requests to
the specific node. After a threshold number of
requests, the RS assumes that the node has failed
and deletes the node information.
Message Losses: Message losses can manifest
themselves in the same fashion as the node failure.
The message initiator, i.e., node, RS or BS, will
make multiple attempts to elicit a response from
others. One of the retries will succeed in obtaining
the response. There may be cases where the mes-
sages are lost only for a set of recipients. A RS or
a BS can lookup its organization information and
send messages to only the set of the recipients that
did not respond to the previous attempts. A leav-
ing node or a RS may not wait for a confirmation
from all the recipients. Existing members in the
network can periodically send hello messages to
confirm their individual presence. When a RS
or BS does not receive a response to the hello
messages from certain members, they make an

In the description so far, we have assumed that
there is only one RS for each AO and only one
BS for each VO. However, depending on the
size of the network and the distances between
the components, there could be several RSs per
AO and several BSs per VO to facilitate address
assignment and resource discovery.

Nodes

Within an AO, the nodes will register with the
nearest RS. Each RS will maintain information
about all other RS within an AO. It is possible
that registration request for a node is sent to more
than one RS. In this case, the first RS to receive
the information will send an enter_node response
to all other RSs within the AO in order to avoid
duplicate registration. For the node discovery,
the RS will first check with the local RSs before
forwarding the discover request across the VO.

RS

When a new RS is added to the grid, it will send
enter_RS message to all the existing RSs within
an AO, as well as to the associated VOs and BSs.
In response, the RSs will send their information