Emerging Paradigms · Study deck

DTN Epidemic Routing

A protocol means an agreed set of rules for passing data.

Blueprint Bina is your guide for this deck.

adhocepidemicrouting
Blueprint Bina, the module guide, in a scene from this chapter.
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After studying this chapter

Learning objectives

You will be able to:

  • Explain: In Figure: Each useful contact is a chance to copy, t0 — Source S creates and stores message M42 starts the TTL and copy limits while S owns: M42 — copy 1.
  • Explain: Epidemic routing improves the chance of eventual delivery by giving a payload more potential carriers, but every new carrier consumes storage and may spend airtime and energy later.
  • Explain: At: T=1 — Exchange IDs, A and B first compare a summary vector and only then copy; that ordering prevents a transmission when the peer already has P1.
  • Explain epidemic routing as bounded store-carry-forward replication
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Major section

Begin With One Copy

Also check what happens when the note is old or the store is full.

  • A protocol means an agreed set of rules for passing data.
  • One phone holds a safety note.
  • When the teams meet, the note can be copied.
  • Later, either team may meet the base camp.
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Major section

Flooding as DTN Trade-off

Epidemic routing improves the chance of eventual delivery by giving a payload more potential carriers, but every new carrier consumes storage and may spend airtime and energy later.

  • At: T=1 — Exchange IDs, A and B first compare a summary vector and only then copy; that ordering prevents a transmission when the peer already has P1.

Why it matters

At : T=1 — Exchange IDs, A and B first compare a summary vector and only then copy; that ordering prevents a transmission when the peer already has P1.

Epidemic routing uses contact opportunities to grow copies until delivery, expiration, or a configured limit stops forwarding.
Epidemic routing uses contact opportunities to grow copies until delivery, expiration, or a configured limit stops forwarding.
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Major section

Flooding as DTN Trade-off (continued)

By: T=2 — Copy Spread, the drawing shows 4 copies, making the exponential sequence 1, 2, 4, 8,. Concrete.

  • The protocol does not contain an automatic notion of “enough,” so: T=3+ — Stop Rule must supply one: delivery,: TTL expiry, buffer policy, or a replication limit.
  • That progression connects store-carry-forward reliability to the chapter's resource argument.
  • A routing design is incomplete if it celebrates extra delivery paths without also specifying which rule halts copying and which queued payload loses capacity while P1 remains live.
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Major section

Flooding as DTN Trade-off (continued)

The short timeline establishes that copies can grow quickly; the next question is what must happen at each encounter before that growth is justified.

  • In Figure: Each useful contact is a chance to copy, t0 — Source S creates and stores message M42 starts the TTL and copy limits while S owns: M42 — copy 1.
  • The later t4 encounter shows why that inventory check matters: B and C both list M42, so no payload crosses the link.
  • The event trace explains how individual copies are admitted, but a deployment decision also needs a network-wide view of the resulting state.
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Major section

Stop Epidemic Copies After Delivery

The replica charts show the benefit and cost together: more carriers improve contact chances but consume storage, airtime, and energy.

  • Starting from one carrier, ideal pairwise spreading can grow as 1, 2, 4, and 8 copies across contact rounds.
  • The summary exchange should suppress that duplicate DTN transfer.
Epidemic routing uses contact opportunities to grow copies until delivery, expiration, or a configured limit stops forwarding.
Epidemic routing uses contact opportunities to grow copies until delivery, expiration, or a configured limit stops forwarding.
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Deck summary

Key takeaways

Also check what happens when the note is old or the store is full.

  • Epidemic routing improves the chance of eventual delivery by giving a payload more potential carriers, but every new carrier consumes storage and may spend airtime and energy later.
  • By: T=2 — Copy Spread, the drawing shows 4 copies, making the exponential sequence 1, 2, 4, 8,. Concrete.
  • The short timeline establishes that copies can grow quickly; the next question is what must happen at each encounter before that growth is justified.
  • The replica charts show the benefit and cost together: more carriers improve contact chances but consume storage, airtime, and energy.
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Retrieval practice

Recall check 1 of 3

Blueprint Bina says: answer from memory, then check your reasoning.

Q1When is epidemic routing a defensible DTN choice?

AWhen the network is intermittently connected, delivery opportunity matters, and the design records TTL, copy, buffer, energy, and priority limits.
BWhen the deployment's primary goal is the lowest possible bandwidth, storage, and energy use per delivered message across the whole network.
CWhen a stable end-to-end route usually remains available during each exchange and the deployment mainly needs low-overhead delivery on that path.
DWhen ample flash storage allows the team to retain messages without specifying expiry or per-message copy limits during deployment planning.
Show answer

Answer: A Epidemic routing is a deliberate trade: it improves delivery opportunity in intermittent networks by spending bounded copies, buffer, contact time, and energy.

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Retrieval practice

Recall check 2 of 3

Blueprint Bina says: answer from memory, then check your reasoning.

Q2Two DTN nodes meet for a short contact. What should happen before payload transfer in epidemic routing?

AThey exchange summary vectors, identify missing eligible messages, then transfer selected copies within the contact budget.
BThey immediately retransmit every buffered payload to each other without first checking what the other node already carries.
CThey purge all messages older than the current contact from both buffers, regardless of recorded TTL or priority rules.
DThey hold all data until an end-to-end route to each destination appears, exchanging only routing beacons in the meantime.
Show answer

Answer: A Epidemic contacts use summary vectors to avoid duplicate copies, then exchange missing eligible payloads according to copy, priority, and contact-window limits.

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Retrieval practice

Recall check 3 of 3

Blueprint Bina says: answer from memory, then check your reasoning.

Q3Which design finding should fail an epidemic routing review?

AThe design records TTL, copy budget, buffer drop policy, summary-vector behavior, and a delivery-versus-overhead test.
BThe design uses spray-and-wait because pure flooding exceeds the device buffer budget.
CThe design assumes every node can carry unlimited copies and does not define stale-message cleanup.
DThe design prioritizes emergency payloads over routine payloads during short contacts.
Show answer

Answer: C A fieldable epidemic design must bound storage, copies, contact use, expiration, and priority.

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Print reference

Answers

Answer key.

  1. A · Epidemic routing is a deliberate trade: it improves delivery opportunity in intermittent networks by spending bounded copies, buffer, contact time, and energy.
  2. A · Epidemic contacts use summary vectors to avoid duplicate copies, then exchange missing eligible payloads according to copy, priority, and contact-window limits.
  3. C · A fieldable epidemic design must bound storage, copies, contact use, expiration, and priority.
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