Routing

Challenges and Requirements

Major challenges

• Mobility – path breaks, packet collisions, transient loops.

• Bandwidth constraint – channel shared by all nodes in the broadcast region.

• Error-prone and shared channel – take into account the larger BERs in wireless ad-hoc.

• Location-dependent contention – high when the number of nodes increases.

Major requirements

• Minimum route acquisition delay.

• Quick route reconfiguration (handle path breaks).

• Loop-free routing (avoid waste of resources).

• Distributed routing approach (reduce the bandwidth consumed).

• Minimum control overhead (bandwidth, collisions).

• Scalability (scale with a large network – minimize control overhead).

• Provisioning of QoS (provide QoS levels) - support for time-sensitive traffic.

• Security and privacy (resilient to threats and vulnerabilities).

Proactive and Reactive Protocols

Which approach achieves a better trade-off depends on the traffic and mobility patterns.

Proactive protocols

• Always maintain routes.

• Little or no delay for route determination.

• Consume bandwidth to keep routes up-to-date.

• Maintain routes that may never be used.

OLSR - Optimized Link State Routing Protocol

Reactive protocols

• Lower overhead since routes are determined on demand.

• Significant delay in route determination.

• Employ flooding (global search).

• Control traffic may be bursty.

AODV - Ad Hoc On-Demand Distance Vector Routing