redzilla
Topic

Layer 2

Switching: MAC, VLANs, STP and link aggregation.

Learn first

Inside the Switch: MAC, VLANs & STP How a switch learns MAC addresses, what a VLAN really does, why STP saves you from storms, and when to bundle links with LAG. ≈ 14 min read →

7 tools

MAC Toolkit

Normalize MAC formats, derive EUI-64 and IPv6 link-local, identify the bits and generate a random MAC.

VLAN Decoder

Decode and build 802.1Q tags: TPID, PCP (802.1p), DEI and VLAN ID, with a binary breakdown.

MAC Vendor (OUI)

Identify a device's manufacturer from the OUI of its MAC address.

Multicast IP ↔ MAC

Convert a multicast IP (IPv4/IPv6) to its destination MAC (01:00:5e / 33:33), show the colliding IPs and the group type.

STP Cost / Root Bridge

Compute STP/RSTP path cost (short and long) by summing links by speed, and find the root bridge by bridge ID.

Link Aggregation (LAG)

Compute a LAG/EtherChannel aggregate bandwidth, the per-flow ceiling, and warn about uneven load-balancing when members are not a power of two.

Q-in-Q (802.1ad)

Encode and decode 802.1ad double tagging: S-TAG and C-TAG with TPID, PCP, DEI and VLAN ID, plus total overhead.