ArticleslgStudy

computer science

On Demand Routing

On Demand Routing is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand On Demand Routing rather than just read about it. In short: On-Demand Routing ("ODR") is an enhancement to Cisco Discovery Protocol (CDP), a protocol used to discover other Cisco devices on either broadcast or non-broadcast media. With the help of CDP, it is possible to find the device type, the IP address, the Cisco IOS version running on the neighbor Cisco device, the capabilities of the neighbor device, and so on.

Key takeaways

  • On Demand Routing belongs to computer science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect On Demand Routing to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of On Demand Routing from memory before moving on to harder problems.

Reference excerpt

On-Demand Routing ("ODR") is an enhancement to Cisco Discovery Protocol (CDP), a protocol used to discover other Cisco devices on either broadcast or non-broadcast media. With the help of CDP, it is possible to find the device type, the IP address, the Cisco IOS version running on the neighbor Cisco device, the capabilities of the neighbor device, and so on. In Cisco IOS software release 11.2, ODR was added to CDP to advertise the connected IP prefix of a stub router via CDP. This feature takes an extra five bytes for each network or subnet, four Bytes for the IP address, and one byte to advertise the subnet mask along with the IP. ODR is able to carry Variable Length Subnet Mask (VLSM) information.

External links ODR, Cisco introduction to ODR

Worked examples

Example 1 — a first encounter with On Demand Routing

Start with the simplest possible case. Write down what On Demand Routing claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to On Demand Routing before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about On Demand Routing ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of On Demand Routing

In research
On Demand Routing appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses On Demand Routing in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
On Demand Routing is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cisco protocols, Computer network stubs, so understanding it makes those chapters shorter.
In everyday life
Look for On Demand Routing outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study On Demand Routing in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what On Demand Routing means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain On Demand Routing out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is On Demand Routing in simple terms?

On-Demand Routing ("ODR") is an enhancement to Cisco Discovery Protocol (CDP), a protocol used to discover other Cisco devices on either broadcast or non-broadcast media. With the help of CDP, it is possible to find the device type, the IP address, the Cisco IOS version running on the neighbor Cisc…

Why does On Demand Routing matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study On Demand Routing?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on On Demand Routing.

Tags

  • Cisco protocols
  • Computer network stubs

Keep exploring