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Lecture notes from university.
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local-network-ethernet-arp.md (1175B)

      1 +++
      2 title = 'Local network: Ethernet, ARP'
      3 +++
      4 ## Local network: Ethernet, ARP
      5 Switched ethernet: ethernet segments connected with switches, which work on link layer
      6 
      7 Switch creates Ethernet segments and forwards frames between segments based on MAC address
      8 
      9 MAC address is 6 bytes, unique among all network adapters, managed by IEEE
     10 
     11 Ethernet frame contains destination and source MAC addresses.
     12 
     13 Link layer switches forward/broadcast/drop frames based on switch table, operate transparently to hosts.
     14 
     15 Generating the table:
     16 - learn new interface mappings from incoming frames
     17 - if destination unknown, broadcast on all interfaces except the source
     18 
     19 Packet transmission:
     20 - store-and-forward: packets received in full, only then forwarded
     21 - cut-through: packet receiving and sending done at the same time
     22 
     23 Avoid loops in network by computing a logical spanning tree, and rebuilding the tree on failure.
     24 
     25 Traffic isolation with VLANs -- subsets of ports.
     26 
     27 ARP: obtaining destination MAC address from a host
     28 - query: whoever has an IP address, respond with your MAC address
     29 - reply comes only from that host and contains MAC address
     30 
     31 NAT: maps an IP address space into another