Link Aggregation

What this chapter covers

The Link Aggregation chapter shows how RouterOS joins several cables into one logical link.

The single syllabus topic is RouterOS bonding. It has two parts: the bonding modes, and the compatibility of those modes with static link aggregation on other equipment.

The two pages split these parts, so you learn the modes first and the matching second.

After this chapter you should be able to do the following:

• Create a bond and name its slaves.
• Describe what each of the seven modes does.
• Say which modes need support on the switch, and which do not.
• Pick a hash policy that spreads traffic well.
• Check a bond with the monitor command and find a failed slave.

How the topics fit together

The first page explains the choices, and the second page applies them to real connections.

The decision is simple in outline.

• If both ends support LACP, use 802.3ad.
• If the other end has a static group, use a static mode such as balance-xor.
• If the other end has nothing configured, use a mode that needs no switch support.

How to use these pages

Each topic page has the same shape, so you can skim for what you need.

• What it is: the idea in plain words.
• How it works: the mechanism, with diagrams and example commands.
• What to remember for the exam: the facts to memorise.
• Common mistakes: the classic traps.
• Check yourself: three questions to test your understanding.

Learn the table of modes and which ones need switch support, because exam questions often give a scenario and ask which mode fits. Then practise the matching with a lab of two routers, one running each mode, and use the monitor command to see the result.