Infrastructure Services

What this chapter covers

Infrastructure Services is about the supporting services that let you reach, watch and measure a network, and the faults that affect them.

The chapter covers how you manage a device, how it reports events, how clients get addresses, and how you measure performance. It ends with the tools that show network health at scale.

Every topic is a troubleshooting topic. Expect to read configuration or output and decide what is wrong.

How the topics fit together

The services fall into access, monitoring and measurement.

• Device management is how you get onto the device and move files.
• SNMP, logging and NetFlow tell you what the device sees and does.
• DHCP gives clients their addresses, including through a relay.
• IP SLA measures delay, jitter and reachability, and can drive failover.
• Catalyst Center Assurance collects the data and shows health across the network.

Several of these share a pattern. A device sends data from a source address to a collector, and a mismatch in address, port or credentials breaks it.

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.

Set up a small lab with a router, a client and a server. Try each service, then break it on purpose and use the show and debug commands to find what you changed.