Hands-on Lab·LPIC-2
Virtual interfaces, bridges and MTU
Objective 205.1 covers advanced network configuration, and the parts that are hard to picture are easiest to learn by building them. This guide creates a dummy interface and a bridge, shows what the kernel does on its own when an address is assigned, and then measures the actual MTU with two pings that differ by 28 bytes and get opposite results.
201: Networking Configuration Guide 15 of 29 Intermediate
- OSUbuntu 26.04 LTS
- Kernel7.0.0-30-generic
- systemd259
- Block devicesone 50 GB disk
- TimeAbout 21 min
| Server Name | IP Address | OS | Roles | CPU | RAM | HDD |
|---|---|---|---|---|---|---|
| LPIC2-A01 | 192.168.0.78 | Ubuntu 26.04 LTS | Primary service host - BIND, Apache, Samba, Postfix. Topic 204 RAID runs on loop devices; this machine has no spare disk | 2 Core | 4 GB | 50 GB |
This guide includes
Use this for advanced network configuration. This matters because an interface will claim an MTU it cannot actually deliver - two pings 28 bytes apart give opposite answers.
- reading addresses, links and the neighbour table
- making a virtual interface, and finding the route nobody added
- building a bridge, which is a switch in software
- separating the MTU an interface claims from the one it has
Before you start
- what-stands-between-a-service-and-its-client
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What the host has, and who it has spoken to
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A virtual interface, and the route nobody added
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A bridge is a switch in software
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The MTU the interface claims, and the one it has