Augmenting the Backpressure Collection
Protocol to Support Multiple Sinks
Varun Shimoga Prakash, Dr. Omprakash Gnawali
Networked Systems Laboratory
Dept. of Computer Science
University of Houston
Problem Statement
• Enable the Backpressure Routing technique to
route packets to multiple sinks within a
network.
Expectations from the Solution
• Small Memory Overhead
• Packet Delivery Performance
• Adherence to conditions imposed by
Backpressure Routing.
Possible Solutions
• Virtualization of Queue Management
• Clustering of Network
• Feedback based model.
Virtualization of Queue Management
• Each node stores its local backpressure to
each of the sink in the network.
• Single Queue of Packets
• Backpressure values create a virtual queue for
each sink.
• Backpressure values propagated through
beacons or snooping.
Source Node 2
Sink Node 2
Source Node 3
Source Node 1
Source Node 4
Sink Node 1
Sink Node 3
2
3
1
{
Sink_1: Active
}
4
2
{
Sink_2: Active
}
3
1
4
2
3
{
Sink_1: 1
Sink_2: 1
}
4
2
3
1
4
{
Sink_3: Active
}
2
3
1
{
Sink_3: 1
}
{
Sink_3: 2
Sink_1: 2
Sink_2: 2
}
1
2
3
2
3
1
{
Sink_3: 2
Sink_1: 3
Sink_2: 3
}
Disadvantages
• More the number of sinks, larger the packet
header and storage of local backpressure to
sinks.
Possible Solutions
• Virtualization of Queue Management
• Clustering of Network
• Feedback based model.
Clustering of Network
• Create imaginary clusters in the network
where sinks are the centroids.
• Controlled Broadcast until packets reach a
node in the desired cluster of a sink.
The Network is clustered around each
Sink. There is an affiliation of each of the
Nodes towards the cluster to which
it belongs.
Source
Sink
Broadcast Message
Broadcast Message
This node has a gradient sloping
towards the local sink. Route message
through Backpressure routing.
Disadvantages
• Controlled Broadcasting does not allow Linear
Networks.
• Without controlled broadcasting, undesirable
redundancy of messages increases.
Possible Solutions
• Virtualization of Queue Management
• Clustering of Network
• Feedback based model.
Feedback Based Model
• Sink sends feedback to the last node before it.
• Feedback propagate to all nodes in network.
• Based on feedback and past performance,
nodes choose their next hop.
Source Node 2
Sink Node 2
Source Node 3
Source Node 1
Source Node 4
Sink Node 1
Task: Send packets from Source Node 3 to Sink Node 1
Sink Node 3
2
3
1
Initially Broadcast
the packet
Broadcast
2
3
1
Broadcast
2
3
Broadcast
1
Negative Feedback
2
Negative Feedback
3
Broadcast
1
Positive Feedback
Sink Node 1
Positive Feedback
2
3
1
Sink Node 1
Sink 1:
Positive Feedback
2
Sink 1:
3
1
Sink Node 1
Sink 1:
Positive Feedback
2
Sink 1:
Sink Node 2
3
1
Sink 1:
Sink 2:
Sink 3:
Sink Node 1
Disadvantages
• Convergence of the entire network takes more
time in case of mobile sinks.
• New weight parameter (feedback) to be
considered to calculate weight.