add ethernet lan part 2

06. Ethernet LAN Switching (part 2).md

@@ -0,0 +1,91 @@
+---
+id: 06. Ethernet LAN Switching (part 2)
+aliases: []
+tags: []
+---
+
+# Ethernet LAN Switching (part 2)
+
+## Ethernet Frame
+
+- The preamble + SFD is usually not considered part of the Ethernet header
+- therefore the size of the Ethernet header + trailer is 18 bytes (6+6+2+4)
+- the minimum size for an Ethernet frame (Header + payload (Packet) + trailer) is 64 [[bytes]]
+- 64 bytes - 18 bytes (header + trailer size) = 46 bytes
+- therefore the minimum payload (packet) size is 46 bytes
+- if the payload is less than 46 bytes, padding bytes are added
+- ie. 34-byte packet + 12-byte padding = 46 bytes
+
+## [[ARP]]
+
+- ARP stands for 'Address Resolution Protocol'
+- ARP is used to discover the Layer 2 address [[Mac address]] of a known Layer 3 address [[IP address]]
+- Consists of two messages:
+  - ARP Request
+    - ARP Request is broadcast = sent to all hosts on the network
+  - ARP Reply
+    - ARP REply is unicast =  sent only to one host (the host that sent the request)
+
+## ARP Table
+
+- command to view the ARP table 
+  - use *[[arp]] -a* ([[Windows]], [[macOS]], [[Linux]])
+  - use *show arp* ([[Cisco]] devices)
+- Internet Address = IP address (layer 3 address)
+- Physical Address = MAC address (layer 2 address) 
+- type static = default entry
+- type dynamic = learned via ARP
+
+## [[Ping]]
+
+- A network utility that is used to test reachability
+- Measures round-trip time
+- Uses two messages
+  - [[ICMP]] Echo Request
+  - [[ICMP]] Echo Reply
+- command to use pin: *ping (ip-address)*
+
+## MAC address table
+
+command to view it 
+  - *show mac address-table*
+
+
+```cisco
+SW1#show mac address table
+
+Vlan  Mac Address     Type    Ports
+----  -----------     ----    -----
+   1  0c2f.b011.9d00  DYNAMIC Gi0/0
+   1  0c2f.b06a.3900  DYNAMIC Gi0/2
+
+Total Mac addresses for this criterion: 2
+```
+
+- [[Vlan]] : Virtual local area network
+- Ports = Interface
+
+## Clearing the Mac address Table
+
+for manually remove mac address table use this command
+  - *clear mac address-table dynamic*
+for just one mac address
+  - *clear mac address-table dynamic address (mac address)*
+  - *clear mac address-table dynamic address 0c2f.b06a.3900*
+for one interface
+  - *clear mac address-table dynamic interface (interface)*
+  - *clear mac address-table dynamic interface Gi0/0*
+
+## Summary
+- Ethernet frame payload minimum size
+- ARP (Address Resolution Protocol)
+  - ARP Request 
+  - ARP Reply 
+- ARP table
+- Ping
+  - ICMP Echo Request
+  - ICMP Echo Reply
+- Mac Address Table
+  
+
+