Linux network

1. Radio broadcast
   multicast multicast
   Unicast unicaset

2. Physical Layer:
   simplex
   half duplex
   Duplex

3. Hub hub: Flooding

4. LAN: broadcast mechanism based
   WAN: Point to Point

5. Ethernet - data link layer
   data transmission: Ethernet II frame structure
   type may be embodied in the upper layer protocol
   destination addr (NIC physical address)
   Source addr
   Data 46-1500bytes

6. Table cam switch
   port corresponding to the mac address, this address is learned from the source address
   switches for blocking collision domains

7. Partition router broadcast domain
   VLAN broadcast domains may be separated -trunk coupled
   on a network with VLAN physically, logically different network segments
   VLAN information in the data frame transmitted in frame, inserting

8. TCPIP stack

9. Bridging vmnet0
   host only vmnet1
   NAT vmnet8
   other vmnet6 / 10 etc.

10. TCP header (header):
    a 20-byte fixed

11. Server ports generally fixed (destination port)
    client port (Source Port) require different
    cat / etc / services
    server port used
    grep 9527 / etc / services

12. Packet number seq
    acknowledgment ACK number
    the TCP sliding window (window size) is determined according to the network each send / receiving several packages

13. Flag bit: 0/1 two states
    the RST RESET
    PSH Push buffer or not
    the URG pointer Urgent
    the ACK Acknowledgment Number
    the FIN Finish
    the SYN Synchronize Sequence Number (communication request and you)

14. TCP three-way handshake:
    requesting end: SYN = 1 other bits are 0 seq = x
    Reflector: SYN = 1 ACK = 1 seq = y ( Reflector their packet number) ack = x + 1
    requester:
    the ACK =. 1 SEQ = x + 1 ack = y + 1

15. TCP four wave:
    requesting end: FIN = 1, seq = u
    Reflector 1: ACK = 1, seq = v, ack = u + 1
    Reflector 2: FIN = 1, ACK = 1, seq = w, ack = u + 1
    requester: ACK = 1, seq = u + 1, ack = w + 1 ( waiting 2MSL)

16. ICMP protocol
    determining network state, often used with the ping

17. ttl: path length through each of a number of routers, the initial value minus one