Doděláme VLAN
DNS
ARP 



Ethernet frame
https://www.geeksforgeeks.org/ethernet-frame-format/

eradeji tohle
https://www.ionos.com/digitalguide/server/know-how/ethernet-frame/
a hlavně a%t si poznamenají preambuli !!!!  


https://en.wikipedia.org/wiki/IPv4#Header
     a tady kolem je to docela hezky 
     
IP address   source  destination
port   source  destination 



arp  protocol 
 Computer 1 has to send a broadcast ARP request message (destination FF:FF:FF:FF:FF:FF MAC address), which is accepted by all computers on the local network, requesting an answer for 192.168.0.55. 
 who has  192.168.123.124 
     
     
netmask   

255.255.224.0
255.255.255.248

broadcast 


protokoly TCP a UDP
  - rozdíly
  
   viz HDLC -   
  
  
  
  
   Peterka je dobrý , i když starý - přečíst 
  https://www.earchiv.cz/a96/a630k150.php3
  https://www.earchiv.cz/a96/a631k150.php3
  
  
SIP - The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating real-time sessions that include voice, video and messaging applications.
RTP - The Real-time Transport Protocol (RTP) is a network protocol for delivering audio and video over IP networks.