AIX 5L Configuring TCP/IP (Unit 01, Part 1): TCP/IP Concepts

Unit Objectives
———————–
List and describe the protocols included in the TCP/IP protocol suite
Define and describe the TCP/IP layering model
Explain network addressing
Define TCP/IP terms of Internet, gateway, router, bridge, switch, repeater, and host
Describe subnet mask and how to use it
Interpret an IP address given the address and its subnet mask
Explain the purpose of multicasting

What Is TCP/IP
————————-
Transmission Control Protocol/Internet Protocol
Internet Protocol Suite
Set of protocols (rules)
Heterogeneous systems
Supports different network types

Requests for Comment (RFC)
——————————————-
RFC 791 Internet Protocol
TCP/IP Standards

Networks
———————-
TCP/IP is communicationn between networks including
LAN – Local Area Network
– Token Ring
– EtherNet Bus

WAN – Wide Area Network
– Direct-Connect Leased/Line
– Public Packet Switching Network
– Dial Up/Modem, Microwave Satellite

VLAN – Virtual LAN
– Ethernet Switch

An Internet
——————
Hardware Adapters – Unique address
Destination Address, Source Address, Data
D, S, Data
IP Address – Internet Protocol Address

TCP/IP Layering for AIX/UNIX
——————————————
1. (ent0) Physical Adapters – Ethernet, TokenRing, Fiber, x.25, Serial, ATM, Etherchannel
2. (en0) Network Interface – Ethernet, TokenRing, x.25, PPP, ISDN, Serial, Loopback(Software Only), SLIP, FDDI, IEEE802.3, ATM
3. Internet – IPv4, IPv6, ICMP, ARP
4. Transport – TCP, UDP
5. Application – FTP, HTTP, DNS, TFTP, TELNET, SMTP, NFS, NIS, SNMP

ODM – Object Data Manager (Creates new objects when the adapters are discovered)
ent0 – Physical Adapters
en0 – Network Interface (IP Address assigned in the ODM to en0)

LAN Physical Address (48 Bit)
———————————————
48 Bit Hardware Address – Ethernet or Mac address
00000010, 01100000, 10001100, 00101110, 10011011, 11001010 – Binary
02:60:8C:2E:9B:CA or 02608C2E9BCA – Hexadecimal

IP Protocol
——————
Packet delivery protocol (datagram)
IP addressing specifies the source and target hosts
Handles the routing of packets to other machines in the network or other networks
Packet fragmentation and reassembly

Internet Address (32 Bits)
————————————-
32 Bit Address
10000001, 00100001 || 10010111, 00000111
129 . 33 . 151 . 7
Dotted Decimal

Two Address Portions (Movable Boundry)
– Network Address
– Local Host Address

Binary to Decimal Conversion Review
——————————————————-
1 1 1 1 1 1 1 1 – Binary
128, 64, 32, 16, 8, 4, 2, 1 – Decimal Value = 255
1 0 0 0 0 1 1 1 – Decimal Value = 136

Internet Addressing (32 Bits)
—————————————-
Class A – 1-127 (Large Companies) – 0 || Net-Id (7-Bits) || Host-Id (24-Bits)
Class B – 128-191 (Medium Companies) – 01 || Net-Id (14-Bits) || Host-Id (16-Bits)
Class C – 192-223 (Small Companies) – 110 || Net-Id (21-Bits) || Host-Id (8-Bits)
Class D – 224-239 (Multicast Address) – 1110 || Net-Id (28 Bits)
240-255 Not used currently

Special Internet Addresses
—————————————-
127.0.0.1 – Loopback (Used to allow machines to use the TCP/IP protocol to talk to itself – Does not go through an adapter)
Network Address || 00000000000000000 – Identify a Network
Network Address || 11111111111111111 – Broadcast Address (To all machines on the network)

Address Assignment
——————————–
Private Internets (Class A 10 – – – )
– Choose any valid addresses/names(within reason)
– Should use reserved private network addresses (RFC 1918)
Class A 10 – – –
Class B 172.16.—172.31.—
Class C 192.168.0.- – 192.168.255.—

The Internet
– American Registry for Internet Numbers (ARIN)
– Reseaux IP Europeens (RIPE)
– Asia Pacific Network Information Center (APNIC)
– Other regional/national registries

Physical and Logical Addressing
————————————————
Used by Address Type Mapping
———— ——————– ————
People Host Name
Software Logical Address Name Resolution
Hardware Physical Address Address Resolution

Address Resolution Protocol (ARP)
—————————————————-
Builds table of IP address to physical address mappings
IP uses the table to tell a network interface where to send data packets
arp command is used to view ARP entries

sys1 – 128.10.1.1 (00608C2FB5A5)
sys2 – 128.10.1.2 (00608C2FB5A6)

Note: If an IP address is not known in the ARP table then the system will broadcast a message to all of the devices on the network asking for device to respond that belongs to that address. None of the other devices will respond. The correct device will respond with its hardware address and it is place in the ARP table for use.

ICMP Protocol
———————
Integral to IP operation, but functionally separate
ICMP messages are sent using IP datagrams
Used to communicate error and control messages for IP
Reports errors on any IP datagram with the exception of IP datagrams containing ICMP messages

ICMP echo request known as ping

Ports and Sockets
—————————-
Source Destination
128.66.12.2 192.178.16.2
sys1 Socket sys2
Application <========> Application
Port Port
Port Port
Transport Transport
IP IP
Internet Internet
Network Network
Physical Physical
^————————————-^
API Interface is referred to as a Socket
Socket – IP and Port Communication End Point
Port#
Protocol
IP Address

/etc/services – table of port numbers and Network services
# Network services, Internet style
telnet 23/tcp
ftp 21/tcp

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