DSDV Routing Table Workbench

Step through proactive table broadcasts, destination sequence numbers, metric comparisons, stale update rejection, and broken-route propagation

Interactive DSDV animation for learning proactive ad-hoc routing tables, full dump and incremental updates, destination sequence numbers, loop avoidance, stale update rejection, and broken-route handling.

Animation DSDV Sequence Numbers Proactive Routing

DSDV Routing Table Workbench

Watch a proactive ad-hoc router process table updates. DSDV keeps routes ready before traffic arrives, but every update must be judged by destination sequence number first and hop metric second to avoid loops and stale information.

Step 0/0Update progress

ReadyBroadcast type

No decisionRoute action

A to D: unknownSelected route

Scenarios

Controls

Focus node A

Destination D

What To Watch

The key learner task is deciding whether an incoming table row should replace the current row.

Sequence firstHigher destination sequence number means fresher information.

Metric secondOnly compare hop count when sequence numbers are equal.

Odd sequenceOdd destination sequence number marks a broken route.

Proactive costRoutes are ready, but update traffic is continuous.

MANET Update Scene

Choose Step or Play

No update receivedIncoming table row

Sequence number decides firstDSDV rule

No table change yetReceiver outcome

Selected Node Routing Table

Destination	Next hop	Metric	Seq	Status	Why

Learning Diagnosis

Sequence rule pendingStep through an update to see whether freshness or metric is deciding.

Loop preventionStale distance-vector information is rejected even when it advertises a tempting metric.

Proactive tradeoffDSDV avoids route discovery delay by paying ongoing table-update overhead.

Update Transcript

Quick Reference

Routing Entry

• Destination node
• Next hop neighbor
• Metric, usually hop count in the teaching model
• Destination sequence number and validity state

Accept Rule

• Accept a higher sequence number.
• If sequence numbers are equal, accept the lower metric.
• Reject lower sequence numbers even if the metric looks better.

Update Types

• Full dump: complete table, useful after major change or initialization.
• Incremental: only changed entries, lower overhead.
• Broken route: infinite metric with odd sequence number.

How To Read The Animation

Orange arrowThe sender is broadcasting an update row to a neighbor.

Green pathThe selected node's currently installed next-hop chain toward the selected destination.

Table highlightThe active destination row is the one being tested or changed by the current update.

Technical Accuracy Notes

What Is ModeledThe workbench models DSDV as a proactive distance-vector protocol with destination sequence numbers, hop metrics, full/incremental updates, and broken-route advertisements.

What Is SimplifiedSettling time, advertisement timers, radio MAC behavior, packet formats, and implementation-specific damping are simplified so the route-selection rule stays visible.

Sequence ParityEven sequence numbers indicate valid destination-originated information. Odd sequence numbers are used to advertise route invalidation after a break.

Source Links

Perkins and Bhagwat DSDV paperOriginal DSDV paper describing destination sequence numbers and proactive ad-hoc routing behavior.

IBM Research publication pageBibliographic page for the original DSDV work.

ns-3 DSDV model notesImplementation-oriented notes that show common DSDV model parameters and routing behavior.