Computer Technology and Software Professional Technical Qualification (Level) Examination-Software Test Intermediate Network Engineer Notes Five

BGP

1. The main function of BGP is to control routing strategies ;
2. Transmission via TCP connection , BGP port number 179;
3. It is a distance vector routing protocol.
4. BGP has an AS list to show which autonomous systems it passes through, mainly to prevent self-loops.

 

 

 

 

NAT

1. Static conversion
2. Dynamic conversion M:N N<M
3. M:1 translation, also called disguise (NAPT -Network Address Port Translation)

 

The working principle of the three-layer switch: one route, multiple exchanges. (Will remember the destination MAC address and source MAC address)

 

Multiprotocol Label Switching (MPLS- Multiprotocol Label Switching), can be called 2.5 layer.

MPLS contains three routers:

1. Ordinary router (CE)
2. Border router (LER, PE for short)-tagging
3. Label Switch Router (LSR, P for short)—only forwards based on labels

 

Multicast

1. The multicast group specifies a class D address as the multicast identifier.
2. In the IP multicast mode, the multicast source does not need to know all the group members.
3. Multicast members can come from different physical networks.

 

Multicast reserved address

    224.0.0.1-means all hosts in the subnet

    224.0.0.2—means all routers in the subnet

    224.0.0.5-represents the OSPF router

    224.0.0.6—Indicates the OSPF designated router

    224.0.0.9-means all RIPv2 routers

    224.0.0.12—Indicates a DHCP server or relay agent

    224.0.0.13—means all routers that support PIM

224.0.10-238.255.255.255—Global multicast address, dynamically assigned to a multicast group

239.0.0.0-239.255.255.255—Used as a multicast address in the local subnet.

 

Ethernet multicast IP addresses are mapped to Ethernet multicast MAC addresses, the IP multicast address instead of the low Ethernet 01.00.5e.00.00.00 the low 23 23

 

Group Management Protocol (IGMP) messages are enclosed in IP datagrams for transmission.

The multicast router does not need to know the address of each host in the multicast group

 

 

 

 

 

IP QOS (Quality of Service) provides 3 services

1. Best effort
2. Integrated Service (IntServ) (guarantee quality service, control load service, best-effort service)

Differentiated Services (Each IP packet must be marked with a mark according to its QOS requirements. This mark is called a DS code point . Use the service type field of IPV4 or the communication type field of IPV6 .)

 

Intserv (Integration Service) proposes to provide QOS transmission mechanism through 4 methods

1. 1. Access control
   2. Routing algorithm
   3. Queuing rules
   4. Discard strategy

 

The Resource Reservation Protocol (RSVP) is a one-way reservation from the target to the source.

 

Telnet defines the network virtual terminal (Network Virtual Terminal, NVT )

Telnet adopts client/server working mode

 

 

Simple Mail Transfer Protocol (SMTP) uses TCP connection, TCP port number is 25

Both POP3 (port 110) protocol and IMAP (port number 143) protocol are mail reading protocols.

MIME adds support for multimedia to e-mail.

 

HTTP protocol

 

P2P has no difference between client and server

BitTorrent protocol: In order to share a file, the user generates a streaming file (.torrent) which contains the metadata of the shared file .

Stream file each block using the SHA-1 hash algorithm calculates a checksum method.

 

Kademlia algorithm is a distributed hash table algorithm