====== CCNA - Switch & Router ======

===== TL;DR =====
A **switch** connects devices on the same local network.

A **router** connects multiples networks to each other.

===== Key takeaways =====
  * Switch = layer 2
  * Router = layer 3
  * Switch = MAC Address
  * Router = IP Address
  * Switch = CAM table
  * Router = Routing table

===== Key Differences =====
^ Element ^ Switch ^ Router ^
| OSI Layer | Layer 2 | Layer 3 |
| Address used | MAC (Physical) | IP (Logical) |
| Role | Connects devices on a LAN | Connects different networks |
| Table used | CAM table | Routing table |
| Typical usage | Local network, VLAN, Ethernet ports | Internet, inter-networks |

===== How does it work? =====
**Switch:**
  * Learns MAC addresses by looking at source MAC address from incoming traffic
  * Sends the frame to the right port by checking its CAM table
  * Stays in local network

**Router:**
  * Check the destination IP address
  * Choose the right interface / the right route
  * allow to go from one network to another

===== Simple example =====
PC -> Switch -> Router -> Internet

===== Frequent errors =====
  * Confuse MAC and IP
  * To think a switch routes between networks
  * To forget that a router is required to get out of the LAN

===== Packet Tracer Notes =====
  * Make a small lab with 2 PCs, 1 switch and 1 router
  * Test to ping inside the LAN
  * Test the connection to another network

===== Useful links =====
  * [[ccna:ethernet|Ethernet]]
  * [[ccna:vlan|VLAN]]
  * [[ccna:osi-tcpip|OSI - TCP/IP]]