Volcano Routing Scheme Routing in a Highly Dynamic Environment Yashar Ganjali Stanford University Joint work with: Nick McKeown SECON 2005, Santa Clara,

Volcano Routing SchemeRouting in a Highly Dynamic Environment

Yashar GanjaliStanford University

Joint work with: Nick McKeownSECON 2005, Santa Clara, CA, Sep. 27, 2005

[email protected]://yuba.stanford.edu/~yganjali/

September 2005 Volcano Routing Scheme 2

Outline

Routing in MANETs Slowly changing topology Highly changing topology

Volcano Routing Scheme Single Flow Multiple Flows

Evaluation Mathematical Results Simulations


Routing in Data Networks

Routing in data networks Phase 1: Route discovery

Proactive Reactive or on-demand

Phase 2: Packet forwarding Routing overhead is

reduced Discovery happens very

infrequently

sd


Routing in MANETs

Changes in topology Node movements Wireless link issues

Route changes more frequent Temporary partitioning in

network Increased overhead of route

discovery phase Accelerate/defer the route

discovery process Use flooding to find routes as

quickly as possible Buffer when partitioned


Highly Dynamic Topology

What if topology changes constantly?

Quickly moving nodes Highly dynamic environment Adversarial model

Route discovery failure two-phase routing doesn’t work


One-Phase Routing

Eliminate explicit route discovery Assign a function to nodes that determines

the direction of packets Physical location of nodes:

Some variations of geographical routing Number of packets buffered in a node:

Volcano Routing Scheme (VRS)


Outline





Volcano Routing Scheme (VRS) Lava flows towards the

sea (low altitude) Local balancing of load Obstacles do not stop

lava No explicit route

discovery Reordering layers

doesn’t disrupt the flow


Volcano Routing Scheme

At the beginning of each time slot: Packets are generated at the source.

During the time slot: Each link (v,w) for which P(v) – P(w) >

transfers one packet from v to w. is called transfer threshold.

At the end of the time slot: Packets which arrive at destination are removed.


Simple Example

Time slot 1 Packet generated

Time slot 2 Packet generated Two transfered One received

Time slot 3 Packet generated

Time slot 4 Packet generated One transfered One received

…

s d

m


Volcano Routing Scheme


Pros and Cons

Advantages No explicit route discovery Completely distributed Low complexity Minimal amount of control

traffic Suitable for highly dynamic

environments System is proved to be

stable Path taken by packets is

near optimal

Limitations Requires continuous stream

of packets from source to destination

Packet reordering might happen


Multi-Flow VRS

Time-Division VRS Divide time equally among K flows

Maximum-Pressure VRS For a link (v,w) serve the flow i which has the

maximum amount of pressure Pi(v)- Pi(w)


Multi-Flow VRS


Outline





Evaluation Method

Metrics Stability (packet loss ratio) Queue size distribution Routing path length

Factors Connectivity (communication range, number of

nodes, …) Number and amount of flows Mobility process Transfer threshold


Stability

Strict Stability: total number of packets in the network is bounded.

F-Min-Provisioned: capacity of minimum cut is at least F.

Theorem. If the source injects at most F packets the system remains strictly stable if the network is F-min-provisioned. s d


Packet Loss vs. Flow Demand 100 nodes distributed

uniformly in a 1x1 square

CR = 0.26 Velocity ~ [0.01..0.2] = 2 Average number of

neighbors = 20 Stability independent of

buffer size


Packet Loss: TD-VRS vs. MP-VRS


Packet Loss: Communication Range

Average No. of Neighbors = Flow Demand


Packet Loss: Mobility Process No difference between

random walk and waypoint model

Stability independent of velocity

Extremely low velocity can cause instability


Queue Size Distribution


Near-Optimal Paths

In a fixed topology packets take shortest paths.

If flow rate is D- we can choose such that Almost surely all packets

take the first D shortest paths.

Trade-ff between Number of outstanding

packets Routing path length


Path Length vs. Delta


Summary

Introduced Volcano Routing Scheme Distributed, fast, low complexity, … Need stream of packets

Variations of VRS: Time Division, Maximum Pressure

Stable under admissible traffic Short queuing delay Routing path near optimal


Thank You!Questions?


Extra Slides


Generalizing to More Flows

Flow 1 Source: node 1 Destination: node 4

Flow 2 Source: node 4 Destination: node 1


Packet Loss: Flow Demand


Packet Loss: Number of Nodes


Loss vs. Velocity


Packet Loss vs. Node Velocity


Queue Size Distribution: Delta


Queue Size Distribution

Documents

Volcano Routing Scheme Routing in a Highly Dynamic Environment Yashar Ganjali Stanford University Joint work with: Nick McKeown SECON 2005, Santa Clara,