#18 Cisco device system operations with computer-based conversion

Operating systems for Cisco devices:

Ios:internetwork Operating System, Internet operating system, Bsdunix simplified version

Switch iOS: Several megabytes in size

Router iOS: Several 10 mega sizes

Huawei or H3C's operating system:

Comware:communication Ware, Tong Letter,

Cli:command-line Interface

Cisco switches:

Nexus: High-end core switches

Catalyst: Mid-low-end switch

The hardware structure of the catalyst switch:

Cpu:motorola chip.

Ram:dram, unzip the iOS and Running-config configuration files;

Flash: Flash memory, storage of iOS software image files, the culture saved by the configuration file Config.text;

NVRAM: Non-volatile random memory, storing startup-config files;

ROM: Post (power-on self Test)

Interface: Various types of interfaces, the most common is the Ethernet interface;

Ethernet

Console: Configuration management interface, RJ-45 standard connector,

Back-bone: backplane, providing sufficient bandwidth for each interface controller to complete the duplex communication;

iOS is a modeled operating system

User mode

>

Privileged mode (Enable mode)

#

Global configuration Mode

(config) #

Interface configuration mode

(Config-int) #

VLAN configuration mode

(VLAN) #

(Config-vlan) #

Route mode

(Config-router) #

...

Comware is the operating system that should be based on the view

User View

System View

Interface View

VLAN view

Route view

...

Cisco View commands:

Show

Show Running-config: View the configuration files currently running in RAM;

Show Startup-config: View the configuration file saved in NVRAM;

Write

Copy running-config Startup-config: (recommended)

Save current configuration to NVRAM

Huawei's View commands:

Display

Display Current-config: View the configuration files currently running in RAM;

Display Saved-config: View the configuration file saved in NVRAM;

Save: Saves the current configuration to NVRAM

For an Ethernet switch, its interface type:

ethernet:10mbps

fastethernet:100mbps

gigabitethernet:1000mbps

FastEthernet Slot/interface

Calculates the position of the slot, from right to left, bottom up;

Security of the switch:

Password for user mode

Password that must be entered before entering user mode

Configuring in the configuration mode of the console line

Switch (config) # line console 0

Switch (config-line) # Login

Switch (config-line) # password Input_password

Password for privileged mode

Password that must be entered before entering privileged mode

Configure the password used to perform the Enable command in global mode

Switch (config) # enable Password|secret Input_password

Attention:

1.password subcommand set plaintext password, SECRET subcommand set MD5 encryption password;

2. If the plaintext password and encryption password are set at the same time, the plaintext password is invalid and only the encryption password is valid;

3. You can add no command in front of the configuration command to revoke the corresponding password;

Password for remote connection

A password that is entered before connecting to the switch remotely via the Telnet service and entering privileged mode

Password required to enter user mode after remote connection via telnet on the remote client

Switch (config) # line vty 0 [1-15]

Switch (config-line) # Login

Switch (config-line) # password Input_password

Switch (config) # service password-encryption

Command meaning: Save all current plaintext password encryption and encrypt the plaintext password of all subsequent settings

Switch (config) # no service password-encryption

Command meaning: In the future to set the plaintext password, can be displayed in clear text, and for the password has been encrypted to make no changes;

To set the login banner information before the switch enters user mode:

Switch (config) # banner MOTD "Banner_info"

Physical network segment:

Conflict domain: The maximum extent of the occurrence of a conflict;

The switch can divide the whole network into multiple conflict domains, that is, dividing multiple physical network segments, the way of dividing the physical network segment is called "The differential segment of the network".

Ber:

Fiber: 10^-5

Cable: 10^-7

Wireless: 10^-9

Binary: Carry Count system

Digital: The basic digital symbol constituting some kind of carry-count system;

Cardinality: The total number of all the figures in a carry-count system;

Rights:

Integer: Cardinality ^ (bit-1)

Decimal: Radix ^-bit

123456.789

Binary:

Digital: 0, 1

Base: 2

Rights:

Integer: 2^ (Bit-1)

Decimal: 2^-bit

10001010

1 guests

10 Guests

100 guests

...

10 million guests

2^1=10

2^2=100

2^3=1000

2^4=10000

2^5=100000

2^6=1000000

2^7=10000000 binary

2^1=2

2^2=4

2^3=8

2^4=16

2^5=32

2^6=64

2^7=128 Decimal

2^1=2

2^2=4

2^3=10

2^4=20

2^5=40

2^6=100

2^7=200 octal

2^1=2

2^2=4

2^3=8

2^4=10

2^5=20

2^6=40

2^7=80 Hex

2^3=8^1 any three-bit binary number can correspond to one octal digit

2^4=16^1 any four-bit binary number can correspond to a hexadecimal digit

1000 0000

From binary to decimal:

11001 = 1x2^4+1x2^3+0x2^2+0x2^1+1x2^0 = 16+8+0+0+1 = 25

From decimal to binary:

76 = 64+8+4 = 1000000+1000+100 = 1001100

Subnet mask and sub-network partitioning

The switch can divide the conflict domain, divide a conflict domain into multiple conflict domains, and make the scope of the conflict domain smaller.

Splitting the conflict domain is dividing the physical network segment--Micro-segmentation

The router can divide the broadcast domain, divide a broadcast domain into multiple broadcast domains, and make the scope of the broadcast domain smaller.

Dividing the broadcast domain is the division of the logical network Segment-subnet division;

The use of subnet masks enables the division of logical Segments:

Subnet Mask:

32bit binary composition of the number;

Use 1 to indicate the network bit in the IP address, and 0 for the host bit in the IP address;

The bits in the IP address corresponding to 1 in the subnet mask is the network bit, and the bits in the IP address corresponding to the subnet mask 0 is the main camera;

The two mechanism bits in the IP address of 1 identified in the quilt netmask must be the same, and the bits in the IP address of the 0 identified in the quilt mask is ignored;

For example:

What is the subnet mask for the 121.88.99.21 address?

11111111.00000000.00000000.00000000

255.0.0.0

172.16.9.8

10101000.00010000.00001001.00001000 IP Address

11111111.11111111.00000000.00000000 Subnet Mask

10101000.00010000.00000000.00000000

172.16.0.0 Network Address

172.16.99.88

10101000.00010000.01100011.01011000 IP Address

11111111.11111111.00000000.00000000 Subnet Mask

10101000.00010000.00000000.00000000

172.16.0.0 Network Address

172.16.99.99 has class IP address 255.255.0.0

10.1.2.3 has class IP address 255.0.0.0

192.168.100.100 has class IP address 255.255.255.0

172.16.99.100/255.255.255.0 No class IP address

Prefix notation for non-class IP addresses:

172.16.99.100/24

netmask. Subnet mask. Host

Subnetting is actually to increase the number of network bits in the IP address, reduce the number of host bits, so as to reduce the broadcast domain range, reducing the number of hosts in the logical network segment, convenient management and security policy for the precise application;

172.16.0.0/24

172.16.1.0/24

172.16.2.0/24

...

172.16.255.0/24

The number of network bits is increased, and the sub-network (2^ network bit) is divided.

The root effect of the subnet mask:

A "logical and" operation with an IP address to determine the network address of the IP address;

Routing Basics

The router makes data forwarding based on the routing table:

If the routing table has a route entry corresponding to the destination IP address of the packet, it is forwarded according to the relevant routing entry;

If the routing table does not have a route entry corresponding to the destination IP address of the packet, the packet is discarded;

The routing table is the key to whether the router can forward data;

How does the routing table appear in the Router?

1. The routing table is a set of data information with a certain standard format;

2. If the information received by the Administrator is added to the routing table, such routing information is called static routing;

3. If it is the routing information that the routers communicate with each other through a specific protocol, it is called dynamic routing;

4. In general, static routes are permanently valid, and dynamic routing is valid for a specific time frame;

What is the routing entry like?

Source destination network address for route entry [administrative distance/measure] via Next hop address

Source of the route entry:

C: Route entry for direct routing, IP address configured on the physical interface of the router

S: Static route

D, R, O, o E1, o E2, D EX, B: Dynamic routing

s*: Static default route

d*, o*: Dynamic default route

Destination network address:

Network address, which is the IP address of all 0 of the main camera;

Using the subnet mask identified by the destination network address and the destination IP address in the packet, the result is compared with the "Destination network address", and if it is identical, the matching is forwarded; otherwise, the next route entry is matched; if all the routing entries do not match the destination IP address, The packet is discarded;

Management distance: Evaluation of the route selection method is good or bad; the smaller the number the better, the bigger the worse;

Measure: In the same way of routing, the smaller the path of the measure, the better;

The above two parameters are used to judge whether the path is excellent, or, this is the basis of routing choice;

Next-hop address (number of outbound interfaces): If the router can route the packet normally, the parameter indicates the direction of the route data;

#18 Cisco device system operations with computer-based conversion