Module 13
VLANs and trunking
Many networks on one set of switches. Tag frames, carry several VLANs over a trunk, and see why two hosts on the same switch may still need a router.
Start lesson 1
Who hears a broadcast? · 7 min · free, no account
LinkOpen now
What you'll operate
- Broadcast domains
- 802.1Q tags
- Access and trunk ports
- lessons
- 6
- minutes
- 47
Lessons in this module
- 1Who hears a broadcast?See how far a message sent to everyone travels, and how a VLAN fences it in.Free, no account7 min
- 2How does a VLAN cross between switches?Follow a frame in through an access port, over a trunk with a tag on it, and out the other side.Plus8 min
- 3What is inside a VLAN tag?Take the four bytes of an 802.1Q tag apart field by field, and see what they do to the size of a frame.Plus8 min
- 4What happens to an untagged frame on a trunk?Meet the native VLAN, the one VLAN a trunk carries without a tag, and the fault when two switches disagree about it.Plus8 min
- 5Why do two PCs on one switch need a router?Send a packet from one VLAN to another and follow it up the trunk to a router and back down again.Plus8 min
- 6Can a frame break out of its VLAN?Follow a double-tagged frame into a VLAN it should never reach, then find and close the gaps that let it through.Plus8 min
Lesson 1 is open to everyone, with no account. The other lessons in this module are part of Plus.