Shulou(Shulou.com)06/01 Report--

Topology Topology

CAM memory addressable table, MAC address and packet interface

Dynamic mac aging time 100s

FSC frame check sequence MD5 check

Unicast

Multicast

Broadcast layer 3 address 255.255.255.255 layer 2 address FF.FF.FF.FF

Local area network

Four collision domains and one broadcast domain

Wide area network

Bandwidth bandwidth

Duplex duplex mode

Ip is already recognized by layer 3 switches

The network segment is the broadcast domain

Two broadcast domains

11 collision domains

OSI

Open system interconnection

PDV

Add headers on each floor:

In the four layers of Fragment data segment

After the three-layer processing of Packet packet

The only unit transmitted in the network after layer 2 processing of Frame data frames

Encapsulation process

Unpacking process

TCP/IP protocol stack

Application layer, transport layer, network layer, data link layer

According to the content of the protocol, TCP/IP can be encapsulated in a hop layer.

High-layer packaging is the most essential difference between TCP/IP and OSI

Application: application layer

HTTP: the purpose is to browse the web, based on TCP port number 80.

HTTPS: a secure hypertext transfer protocol for secure web browsing, based on TCP port 443.

FTP: file transfer protocol, used for high-speed long transmission and download of large numbers of data files, based on the TCP port number 20 ~ 21.

DNS: domain name resolution service, which is used to convert the URL of PC web pages into IP addresses, based on the UDP port number of 53. 0.

SMTP: simple Mail transfer Protocol, used to send E-Mail, based on TCP port number 25.

POP3: post Office Protocol version 3, used to receive E-Mail, based on UDP port 110.

Exchange: it can be used to receive E-Mail and send E-Mail.

DHCP: dynamic host configuration protocol used to make PC and servers forget whether devices can automatically receive IP addresses, subnet mask gateway addresses, etc., based on UDP port number 68.

TFTP: simple File transfer Protocol, used to transfer small batches of data files, usually used to manage the IOS operating system of network devices and configuration files, based on UDP port number 69.

Telnet: terminal emulation protocol used to enable the network administrator PC to remotely manage the equipment through the Internet. Based on TCP port number 23.

Ssh: secure shell, purpose and telnet, just encrypt the network management session, the encryption is based on RSA. Based on TCP port number 22.

SNMP: a simple network management protocol that allows network administrator PC to manage all network devices at the same time.

NTP: network time protocol, used to synchronize network clocks between network devices and NTP servers, based on UDP port number 123.

MARS log server

Connection-oriented service (reliable transmission), connectionless service (best-effort transmission).

Host-to-Host: host to host layer

TCP: transmission control protocol, connection-oriented protocol, providing reliable forwarding of application data streams

1. The window window field is used to prevent congestion in the transmission of data traffic from TCP-based applications.

(TCP SLOW START TCP starts slowly, starting to the power of 2 to the power of 0. after constantly accumulating to the limit, the processing is halved. )

2. Sequence sequence number 32bit prevents transmission from being out of order

(Delay transmission delay, forwarding delay, serialization delay, queue delay. A group of consecutive messages sent by Jitter is out of order when it arrives at the opposite end due to different delays.

3. ACK acknowledgement number prevents packet loss during transmission.

4. CheckSUM check and, to provide integrity check

5. The retransmission mechanism Sequence and ACK are completed together.

UDP: user Datagram protocol, which is connectionless.

ICMP: Internet Control message Protocol, which includes a series of network work used with IPV4. The classic one is that PING.PING consists of two messages, one is Echo Request and the other is Echo Reply.

RTP: real-time transport protocol, usually used in conjunction with UDP to provide anti-disorder function for VoIP traffic, because the protocol defines sequence numbers.

Internet: Internet layer

IPv4: Internet Protocol version 4, the main purpose of this protocol is to define IPv4 addresses. The length of the address is 32bit, represented in dotted decimal, using 4 segments, each with a value range of 0-255decimal.

IPv6: Internet Protocol version 6, the address length is 128 bits, XXXX, XXXXXX, XXXX, XXXX,

IPX

AppleTalk

Novell

DEC

Network-interface: network interface layer

LAN

Ethernet: Ethernet Ethernet2 IEEE802.3 MAC MA (multiple access)

Token Ring: token Ring

FDDI: optical fiber distributed data interface

WAN

HDLC: high-level data Link Control Protocol Serial

PPP: point-to-point protocol AAA Authentication Authorization Accounting PPPoE PPP Over Ethernet

Frame Relay: frame Relay × ×

ATM: asynchronous transfer mode QoS Quality of Service

Physical layer

Media type media

Ethernet

Twisted pair:

Orange, white, orange, green, green, blue, blue, brown, white

According to non-shielding

Shielded twisted pair: STP, transmission distance 25m

Unshielded twisted pair: UTP, transmission distance 100m

By bandwidth

EIA/TIA:OSI physical layer specification standard, 1 2 3 4 5 5 E 6 7 AMP

CAT 1 CAT 2 cannot transfer Ethernet data and is generally used in the field of telecommunications

CAT 3, which can be used for data transmission of Ethernet. The maximum bandwidth that the cable can provide is 10MBbit/s.

CAT 4, which can be used for data transmission of Ethernet. The maximum broadband that the cable can provide is 16Mbit/s.

CAT 5, which supports the transmission of the maximum 100Mbit/s. Commonly used when connecting PC and servers to the switch.

CAT 5e, which supports the transmission of 1000Mbit/s.

CAT 6 CAT 7, the same as 5e, only improves the process.

CAT 8

Classify by use

Straight-through line: if both ends are EIA/TIA 568B sequence, the cable is a straight-through line. The interconnection of heterogeneous devices uses a straight-through line (1326 1236 100 megabit bandwidth requires only four cores, two receivers and two hair, and eight gigabits)

Crossover: if one segment at both ends is 568B and the other is 568A, the cable is a crossover. The interconnection of similar devices uses cross lines.

EIA/TIA 568B: orange, white, green, green, blue, blue, green, brown and brown

EIA/TIA 568A: green, white, green, orange, white, blue, blue, white, orange and brown

UTP Implementation: Straight-Through vs. Crossover

Coaxial cable

Thick cable: the maximum transmission distance supported is only 500 meters. The only maximum broadband available is 10Mbit/s

Thin cable: the maximum transmission distance supported is only 185 meters. The only maximum broadband available is 10Mbit/s

Optical fiber

Multimode fiber: supports multiple modes of optical fiber, generally thick core, the highest support 1000Mbit/s, the longest support 1KM.

Single-mode optical fiber: only supports a single mode of optical fiber, the general core is relatively thin. Support maximum 10Gbit/s bandwidth and maximum 100KM

Connector type

Twisted pair: RJ45

Coaxial cable

Thick cable BNC

Thin cable N-type reversal joint

Optical fiber

Multimode

Single mode

SC ST

Signaling type:

Client signaling: a control signal transmitted directly by the man-machine to tell the user what to do next.

Office signaling: direct transmission between devices and devices, which is used to control the transmission rules of the device to the data flow.

Baseband transmission: applied to local area network

Carrier propagation: application in wide area network

10 10Mbit/s bandwidth

Base based on baseband transmission

2 the transmission distance is 200m

T twisted pair twisted pair

CSMA/CD

Principle of 5-4-3: maximum range of 5 hubs in a conflict domain, 4 100-meter twisted pair, 3 of 5 hubs connected to pc,2 network only to increase network distance

The smaller the collision domain, the better. Try not to let the hub connect to the limit hub.

The smaller the broadcast domain, the better

Header Hearder

Second floor

MAC

Early use of Ethernet II

Lead code: 8byte

Destination MAC address: 6byte

Source MAC address: 6byte

Length: 2byte

FCS only verifies the frame header

802.3 the 8-byte lead code is divided into 7-byte lead code and 1-byte frame start delimiter.

Type: 2byte tells the switch whether layer 3 uses Ipv4 or ipv6 0x0800 ipv4,0x86DD ipv6

Three layers

Ipv4 ipv6

Ver version

IHL header length

Type of Service is responsible for QoS (transfer important data as much as possible with limited bandwidth, abandon FIFO)

Packet Length message length

Ipv4 is sliced in three layers to meet the requirements of MTU (1500).

Identification identification

Flag: X DF MF MF is defined as packet loss if 0 indicates the end of the fragment.

Frag.Offset identifies data fragments

Time to Live: generally, the default time of existence of 255messages is TTL value accumulation-1 operation.

Protocol: upper layer protocol field that identifies what protocol is used in layer 4 of the transport layer

(ICMP:1 IGMP:2 PIM:13 TCP:6 UDP:17 EIGRP:88 OSPF:89) the protocol number represented by the layer 4 protocol at layer 3

Header Checksum: data integrity check for packet headers

Source Address:32 bit source ip address

Destination Address:32 bit destination ip address

Fourth floor

UDP Header length fixed length 8Byte

TCP Hearder length 20-60Byte, main header 20byte

16-Bit source port: source port number

16-Bit destination port: destination port number

32-Bit sequence number: preventing disorder

32-Bit acknowledgment number: prevent packet loss and retransmission

4-Bit header length

TCP control bit: syn tcp handshake ack fin dismantling an existing tcp session rst Recet forced disconnect

16-Bit window size: flow prevention and control

16-Bit TCP checksum: prevent tampering with messages

16-Bit urgent pointer: emergency pointer

Campus network architecture

Hierarchical redundant architecture

Twisted pair 100m is recommended for Access access layer end-user access network.

High port density, using layer 2 switch, Catalyst 2960 Series Switches

Distribution aggregation layer switch recommends using precursory optical port 1000m.

Based on device connectivity, various network policies are defined. Catalyst 3560\ 3750 (3750 has more stacking capabilities than 3560) Series Switches belongs to layer 7 switch

(can identify which layer of message to distinguish which layer of switch)

Core Core layer 10000m

For the backbone link in the campus network, the optical port density and bandwidth should be large, so applications such as ACL should not be added to this device.

Catalyst 4500Universe 6500Universe 7000 Series Switches (7000 supports CLOS architecture)

One line connection, there is no IP address at both ends or one end, layer 2 connection

Layer 2 technology: WLAN,VTP,STP

The convergence layer connects the core layer and the core layer, and the three-layer connection

Layer 3 technology: routing protocol, QoS, layer 3 language

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