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Routing-and-Switching

Layers

Short:

All People Seems To Need Data Processing

TCP-IP

Network Devices

Transformations

2 value 10 value
10000000 128
11000000 192
11100000 224
11110000 240
11111000 248
11111100 254
11111111 255

Double in 10

6 value 2 value 10 value
0 0000 0
1 0001 1
2 0010 2
3 0011 3
4 0100 4
5 0101 5
6 0110 6
7 0111 7
8 1000 8
9 1001 9
A 1010 10
B 1011 11
C 1100 12
D 1101 13
E 1110 14
F 1111 15

Hex-2-10

Hierarchy scheme for IP address

  • 10 : 172.16.30.56
  • 2 : 10101100.00010000.00011110.00111000
  • 6 : AC.10.1E.38

Protocols

Typical Port Use

TCP UDP
Telnet 23 SNMP 161
SMTP 25 TFTP 69
HTTP 80 DNS 53
FTP 20, 21 DNS 53
DNS 53 -
HTTPS 443 NTP 123
SSH 22 -
POP3 110 -
IMAP4 143 -

DNS can use TCP and UDP

TCP Segment

TCP Segment Format

Putty view

TCP - Transport Control Protocol
Source Port: 5973
Destination Port: 23
Sequence Number: 145389907
Ack Number: 12420545
Offset: 5
Reserved: %000000
Code: %011000

Ack is valid
Push Request

Window: 1320
Checksum: 0x61a6
Urgent Pointer: 0
No TCP Options
TCP Data Area:
vL.5.+.5.+.5.+.5   76 4c 19 35 11 2b 19 35 11 2b 19 35 11
2b 19 35 +. 11 2b 19
Frame Check Sequence: 0x0d00000f

UDP Segment

UDP Segment

Puty view

UDP - User Datagram Protocol
Source Port: 1085
Destination Port: 5136
Length: 41
Checksum: 0x7a3c
UDP Data Area:
..Z......00 01 5a 96 00 01 00 00 00 00 00 11 0000 00
...C..2._C._C 2e 03 00 43 02 1e 32 0a 00 0a 00 80 43 00 80
Frame Check Sequence: 0x00000000

IP Segment

IP Header Block

Putty view

IP Header - Internet Protocol Datagram
Version: 4
Header Length: 5
Precedence: 0
Type of Service: %000
Unused: %00
Total Length: 187
Identifier: 22486
Fragmentation Flags: %010 Do Not Fragment
Fragment Offset: 0
Time To Live: 60
IP Type: 0x06 TCP
Header Checksum: 0xd031
Source IP Address: 10.7.1.30
Dest. IP Address: 10.7.1.10
No Internet Datagram Options

IP Type = Protocol block

Protocol block - Typical Port Use

Protocol Protocol Number
ICMP 1
IP in IP 4
TCP 6
UDP 17
EIGRP 88
OSPF 89
IPv6 41
GRE 47
Layer 2 tunnel (L2TP) 115

Sub-networks

Class Format Default Sub-Mask
A network.node.node.node 255.0.0.0
B network.network.node.node 255.255.0.0
C network.network.network.node 255.255.255.0

2^8 = 256

Classeless Inter-Domain Routing (CIDR)

Submask CIDR value
255.0.0.0 /8
255.128.0.0 /9
255.192.0.0 /10
255.224.0.0 /11
255.240.0.0 /12
255.248.0.0 /13
255.252.0.0 /14
255.254.0.0 /15
255.255.0.0 /16
255.255.128.0 /17
255.255.192.0 /18
255.255.224.0 /19
255.255.240.0 /20
255.255.248.0 /21
255.255.252.0 /22
255.255.254.0 /23
255.255.255.0 /24
255.255.255.128 /25
255.255.255.192 /26
255.255.255.224 /27
255.255.255.240 /28
255.255.255.248 /29
255.255.255.252 /30

8 to 15 - A / 16 to 23 A/B / /24 to /30 A/B/C

CIDR Mask Bit Block Subnetwork Host
/25 128 1 bit inc - 7 bit not inc. 128 0 and 128 2 subnetworks, each 126 hosts
/26 192 2 bit inc - 6 bit not inc. 64 0, 64, 128, 192 4 subnetworks, each 62 hosts
/27 224 3 bit inc - 5 bit not inc. 32 0, 32, 64, 96, 128, 160, 192, 224 8 subnetworks, each 30 hosts
/28 240 4 bit inc - 4 bit not inc. 16 0, 16, 32, 48, 64, 80, 96, 112, 128, 144, 160, 176, 192, 208, 224, 240 16 subnetworks, each 14 hosts
/29 248 5 bit inc - 3 bit not inc. 8 0, 8, 16, 24, 32, 40, 48, etc. 32 subnetworks, each 6 hosts
/30 252 6 bit inc - 2 bit not inc. 4 0, 4, 8, 12, 16, 20, 24, etc. 64 subnetworks, each 2 hosts

VLSM

VLSM Network example 2

Application Mask Hosts Block
/25 128 126 128
/26 192 62 64
/27 224 30 32
/28 240 14 16
/29 248 6 8
/30 252 2 4
Network Hosts Block Sub-network Mask
A 14 16 /28 240
B 30 32 /27 224
C 20 32 /27 224
D 6 8 /29 248
E 2 4 /30 252
F 2 4 /30 252
G 2 4 /30 252
H 2 4 /30 252

General IP Troubleshooting

General IP Troubleshooting drawio - 1

  1. CMD > Ping > 127.0.0.1 (if successful - initiate, if not > install TC/IP in host).
C:\> ping 127.0.0.1
Pinging 127.0.0.1 with 32 bytes of data:
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Ping statistics for 127.0.0.1:
Packets: Sent &x0003D; 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0 ms, Maximum = 0ms, Average = 0ms
  1. CMD > Ping > local host (if successful NIC is OK, if not> > NIC cable connection check).
C:\> ping 172.16.10.2
Pinging 172.16.10.2 with 32 bytes of data:
Reply from 172.16.10.2: bytes=32 time<1ms TTL=128
Reply from 172.16.10.2: bytes=32 time<1ms TTL=128
Reply from 172.16.10.2: bytes=32 time<1ms TTL=128
Reply from 172.16.10.2: bytes=32 time<1ms TTL=128
Ping statistics for 172.16.10.2:
Packets: Sent &x0003D; 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0 ms, Maximum = 0ms, Average = 0ms
  1. CMD > Ping > Default Gateway (if successful NIC is OK and coms with local, if not > local physical network problem detected in NIC).
C:\> ping 172.16.10.1
Pinging 172.16.10.1 with 32 bytes of data:
Reply from 172.16.10.1: bytes=32 time<1ms TTL=128
Reply from 172.16.10.1: bytes=32 time<1ms TTL=128
Reply from 172.16.10.1: bytes=32 time<1ms TTL=128
Reply from 172.16.10.1: bytes=32 time<1ms TTL=128
Ping statistics for 172.16.10.1:
Packets: Sent &x0003D; 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0 ms, Maximum = 0ms, Average = 0ms
  1. CMD > Ping > Server (if successful communication with server established, if not potential problem with DNS settings).

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