computer science

VLAN access control list

VLAN access control list 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 VLAN access control list rather than just read about it. In short: A VLAN access control list (VACL) provides access control for all packets that are bridged within a VLAN or that are routed into or out of a VLAN. Unlike regular Cisco IOS access control lists that are configured on router interfaces and applied on routed packets only, VACLs apply to all packets.

Key takeaways

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

Reference excerpt

A VLAN access control list (VACL) provides access control for all packets that are bridged within a VLAN or that are routed into or out of a VLAN. Unlike regular Cisco IOS access control lists that are configured on router interfaces and applied on routed packets only, VACLs apply to all packets. The technology was developed by Cisco on the Catalyst 6500 Series switch platform. VACLs may be used in similar fashion to a SPAN port or network tap, as a way to replicate computer network data that is coming into and leaving from a computer or a network. This is useful if you want to monitor traffic. Often, this configuration is used to facilitate data loss prevention (DLP) or network-based intrusion prevention systems. VACL or VACL Ports can be much more discriminating of the traffic they forward compared to a standard SPAN port. They may be set to only forward specific types or specific VLANs to the monitoring port. However, they forward all traffic that matches the criteria, as they do not have the functionality to select from ingress or egress traffic like SPAN ports.

See also Virtual private network Private VLAN

References http://www.cisco.com/en/US/tech/tk389/tk814/tk838/tsd_technology_support_sub-protocol_home.html http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008013565f.shtml http://www.cisco.com/en/US/products/hw/switches/ps708/products_white_paper09186a008017b753.shtml

Worked examples

Example 1 — a first encounter with VLAN access control list

Start with the simplest possible case. Write down what VLAN access control list 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 VLAN access control list 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 VLAN access control list 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 VLAN access control list

In research: VLAN access control list 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 VLAN access control list 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: VLAN access control list is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer network stubs, Local area networks, so understanding it makes those chapters shorter.
In everyday life: Look for VLAN access control list 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “VLAN access control list” →

Affiliate

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

How to study VLAN access control list in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what VLAN access control list 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 VLAN access control list out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is VLAN access control list in simple terms?

Why does VLAN access control list 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 VLAN access control list?

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 VLAN access control list.