116 knowledge points for a switch

1. Ethernet is initially based on coaxial cable. 1972 Invention, 1979 Xeroxinter and Dec presented Dix edition.

2. In 1983, the IEEE802.3 standard was presented.

3. CSMA/CD communication process, transmission-monitoring-jamming-random waiting-transmission.

4. Traditional Ethernet network Bridge to split the host, with the router to connect the network segment.

5. Switched Ethernet, usually the host is not connected, when the need for communication, through the exchange of equipment to connect to the end of the host, after completion of the disconnect. Switching devices include switched hubs and switches.

6. Switched Ethernet physical logic is all star type. Splits the conflict domain, limits the network conflict to the minimum scope.

7. Rmon A total of nine groups, commonly used port statistics, history, alarms, events 4 groups.

8. Data flow distinction, according to the organization of administrative composition, by host type, according to physical distribution, according to the type of application.

9.80/20 rule, 80% in local, 20% other segment. 20/80 rule, on the contrary.

10. Switch a single hundred megabytes 64-byte packet forwarding 1488810pps, router machine 64-byte packet forwarding small and 100100pps.

11. Three-layer switching technology for the implementation of hardware routing forwarding, forwarding routing table is also by the Software routing protocol established.

12. Three-layer exchange and routing are based on the logical address to determine the path, run three-tier checksum, use the TTL, information processing and corresponding, analysis of the message, with MIB update SNMP management.

13. Three-layer Exchange advantages: Based on hardware packet forwarding, low latency, low cost.

14. Four-layer switching is based on data flow, implementing one route and exchanging multiple times. Consider the port number and protocol field.

15. The design principle of the LAN, examine the physical link, analyze the characteristic of the data flow, adopt the hierarchical model, consider the redundancy

16. LAN Management system function: Configuration function, monitoring function, fault isolation.

17. Network performance, bandwidth and latency must be guaranteed. It depends on an important factor in the type and layout of the cable.

18. Increase bandwidth for users, increase overall bandwidth & reduce the number of users on a shared media.

19. The Fast Ethernet (100M) standard is 802.3u.

20. The use of physical chips from the consultation to complete, do not require a dedicated data message. Send a 16BI message and the entire Paowen is repeated at 16ms intervals.

21. The rate does not go through the same as the negotiation, but the working method can cause problems. A section of forced 10m Full-duplex, the other end will negotiate from 10m Half-duplex.

22. Self-Negotiation priority: 100base-tx Full-duplex, 100base-t4, 100base-tx, 10base-t Full-duplex, 10base-t

23. Gigabit Ethernet Since the negotiation has been implemented, but the Ethernet on the optical fiber can not be successfully negotiated.

24. The switch belongs to the MDIX device and the PC is an MDI device. Physical chip implementation.

25. Semi-duplex using back push pressure (backpressure) technology implementation, flow control.

26. Full-duplex flow control compliance with the 802.3X standard, using 64-byte "PAUSE" Mac frame. The frame is 01-80-c2-00-00-01 by a multicast address.

Pause applied between terminals and switches, can not solve the stable state of congestion, end-to-end flow control and more complex operations than simple stop.

28. Port aggregation applies only to the MAC mechanism of the 802.3 protocol family.

29. Flow Control Command Flow-control

30. Configure Port Aggregation (distributors) link-aggregation PORT_NUM1 to Port_num2

31.3526 enables 3 Ethernet groupings and one optical grouping, 8 per group. E0/1, E0/9, E0/17, G1/1

VLAN partitioning: Port based, Mac based, protocol based, subnet based

33. Virtual Bridge Local Area network (VLAN) standard -802.1q.