computer science

Virtual network interface

Virtual network interface 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 Virtual network interface rather than just read about it. In short: A virtual network interface (VNI) is an abstract virtualized representation of a computer network interface that may or may not correspond directly to a network interface controller. Operating system level It is common for the operating system kernel to maintain a table of virtual network interfaces in memory.

Key takeaways

Virtual network interface 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 Virtual network interface to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Virtual network interface from memory before moving on to harder problems.

Reference excerpt

A virtual network interface (VNI) is an abstract virtualized representation of a computer network interface that may or may not correspond directly to a network interface controller.

Operating system level It is common for the operating system kernel to maintain a table of virtual network interfaces in memory. This may allow the system to store and operate on such information independently of the physical interface involved (or even whether it is a direct physical interface or for instance a tunnel or a bridged interface). It may also allow processes on the system to interact concerning network connections in a more granular fashion than simply assuming a single amorphous Internet (of unknown capacity or performance). W. Richard Stevens, in volume 2 of his treatise entitled TCP/IP Illustrated, refers to the kernel's Virtual Interface Table in his discussion of multicast routing. For example, a multicast router may operate differently on interfaces that represent tunnels than on physical interfaces (e.g. it may only need to collect membership information for physical interfaces). Thus the virtual interface may need to divulge some specifics to the user, such as whether or not it represents a physical interface directly. In addition to allowing user space applications to refer to abstract network interface connections, in some systems, a virtual interface framework may allow processes to better coordinate the sharing of a given physical interface (beyond the default operating system behavior) by hierarchically subdividing it into abstract interfaces with specified bandwidth limits and queueing models. This can imply restriction of the process, e.g. by inheriting a limited branch of such a hierarchy from which it may not stray. This extra layer of network abstraction is often unnecessary and may have a minor performance penalty. However, it is also possible to use such a layer of abstraction to work around a performance bottleneck, indeed even to bypass the kernel for optimization purposes.

Application level The term VIF has also been applied when the application virtualizes or abstracts network interfaces. Since most software need not concern itself with the particulars of network interfaces, and since the desired abstraction may already be available through the operating system, its usage is rare.

See also Loopback Network virtualization Virtual Interface Architecture

References

External links Linux Network Interfaces

Worked examples

Example 1 — a first encounter with Virtual network interface

Start with the simplest possible case. Write down what Virtual network interface 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 Virtual network interface 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 Virtual network interface 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 Virtual network interface

In research: Virtual network interface 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 Virtual network interface 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: Virtual network interface is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer networks engineering, so understanding it makes those chapters shorter.
In everyday life: Look for Virtual network interface 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.

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How to study Virtual network interface in 20 minutes

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

Frequently asked questions

What is Virtual network interface in simple terms?

A virtual network interface (VNI) is an abstract virtualized representation of a computer network interface that may or may not correspond directly to a network interface controller. Operating system level It is common for the operating system kernel to maintain a table of virtual network interface…

Why does Virtual network interface 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 Virtual network interface?

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 Virtual network interface.