Network Elements and Services

CS 695 Network Management Techniques

Network Elements and Services


Prof. P. T. Chung


Outline

1. Networking - Concepts

2. Internet Communication Protocols

3. Network Elements

4. Network Management Related

Protocols


1. Networking - Concepts

Network ClassificationsNetwork TechnologiesNetwork Transmission MediaNetwork Elements


Network Classifications

Networks – Classified by Applications Data Communication Network Telecommunication Network

Networks – Classified by Distance LAN (Local Area Network) MAN (Metropolitan Area Network) WAN (Wide Area Network)


Network Classifications (Conti)

Networks – Classified by Switching Packet Switching Circuit Switching

Networks – Classified by Transmission Media Wired Network Wireless Network


ATMATM

Network Technologies

LANLAN MANMAN WANWAN

EthernetEthernetToken RingToken Ring

GigabitGigabitEthernetEthernet

ISDN (basic rate)ISDN (basic rate)

FDDIFDDIFastFastEthernetEthernet

Frame RelayFrame RelayMAN & SMDSMAN & SMDS

Ban

dw

idth

DistanceDistance


Transmission Media

Media

WirelineTransmission

WirelessTransmission

ElectricConductors

OpticalFiber

TwistedTwistedPairPair

CoaxialCoaxialCableCable Mono-modeMono-mode Multi-modeMulti-mode

RadioRadio

MicrowaveMicrowaveSatelliteSatellite

TransmissionTransmission

InfraredInfrared Laser LinksLaser Links


Network Elements

LAN/Internet Elements:

oRepeateroHuboBridgeoSwitchoRouteroGateway

WAN Elements:o Modemo Repeatero ADM (Add-Drop Multiplexer)o Cross-Connecto Switcho Multiplexero Concentrator


OSI Communication Architecture

ApplicationApplication

PresentationPresentation

SessionSession

TransportTransport

NetworkNetwork

PhysicalPhysical

Data LinkData Link



SessionSession

TransportTransport

NetworkNetwork

PhysicalPhysical

Data LinkData Link

Application protocol

NetworkNetwork NetworkNetwork

Data LinkData Link Data LinkData Link

PhysicalPhysical PhysicalPhysical

Presentation protocol

Transport protocol

Session protocol

Host A IMP 1 IMP 2 Host B


2. Internet Communication Protocols

The TCP/IP Protocol ArchitectureTCP/IP Layers ( or TCP/IP Suite )

Application Layer Host-to-host, or transport layer Internet Layer Network Access Layer Physcical Layer

Transport

Internet

NetworkAccess

Application

PPPPPPSLIPSLIP

RARPRARPARPARP

IPIPIGMPIGMP

BGPBGPOSPFOSPF

ICMPICMP

RIPRIP

UDPUDPTCPTCP

SNMPSNMP

NNTPNNTP

HTTPHTTP

DNSDNS

TELNETTELNET

SMTPSMTP

BOOTPBOOTP

NTPNTP

FTPFTP

DHCPDHCP

TIMETIME

ECHOECHO

Internet Communication Protocol

Data LinkData Link


IP (Internet Protocol)

Mainly provides multiple routes or Routing capabilities.

Protocol Characteristics:

Connectionless, Unreliable IP Addressing:

Every host in TCP/IPnetwork has one 32-bit IP address. 140.131.76.1


IP Address

length： 4 Bytes (32-Bit)IP address:

Network Address Subnet Host Address)

Network

Host

Subnet Host

IP Address Formats





Network Mask

Set 1 for bits in Network Address and Subnet, and set 0 for other bits in IP address Class A 255.0.0.0 Class B 255.255.0.0 Class C 255.255.255.0

IP address Logical AND (Network Mask, IP Address)


Routers and the IP Addressing Principle

• Routers have two or more addresses. One for each interface.


Routing Table

IF ((Mask[i] & Destination Addr) = = Destination[i])

Forward to NextHop[i]


IP Forwarding Process


IF ((Mask[i] & Destination Addr) = = Destination[i])

Forward to NextHop[i]


Port

Each host’s application layer (or processing layer) may have different application, service, or resource. Once a host received data from network, transport layer should have a mechanism to provide and distinquish network application service so that it could send data to correct processing program.

Each upper-level communication application service or program maps to a unique TCP or UDP Port Number.


Common TCP/IP Application Services and Port Numbers

21 FTP23 Telnet25 SMTP53 DNS79 Finger80 HTTP110 POP3119 NNTP123 NTP

53 DNS67 BOOTP69 TFTP161 SNMP162 SNMP-Trap

TCPTCP UDPUDP

Port: 1~1024 ， for Internets


3. Network Elements

Repeater Hub Bridge SwitchRouterRouting SwitchGateway


Repeater

Operates at Layer 1, the physical layer. Connects two network segments into one large

segment, or to expand an existing segment. Enhances data signals and thus can be used to

extend maximum cabling distances. There is no network intelligence built into a simple

repeater; it is used strictly for signal propagation.


Hub

Operates at Layer 1, the physical layer. Simply a multiport repeater. Can be used to increase overall network size and

number of nodes on a single segment. Can isolate faults within the subnet. Allows you to add stations to a segment without

disrupting the entire network.


Bridge

Operates at Layer 2, the data link layer. Allows networks with different physical signaling, but

with compatible data link addressing schemes, to communicate.

Helps reduce traffic on a backbone LAN by filtering any information coming from one segment to another that does not need to be forwarded through the backbone.

A common use for a bridge is to allow users on an Ethernet LAN and a Token Ring LAN to communicate with each other.


Bridge Example



SessionSession

TransportTransport

PhysicalPhysical

NetworkNetwork

Data LinkData Link


PhysicalPhysical


SessionSession

TransportTransport

NetworkNetwork

Data LinkData Link

PhysicalPhysical

Data LinkData Link

PhysicalPhysical

Data LinkData Link

BridgeBridge


Switch

Operates at Layer 2, the data link layer. Dispatches data to its destination, which it

determines from the packet’s lower-layer media access control (MAC) address.

Can limit traffic, and does not understand network protocols.


Router

Operates at Layer 3, the network layer. Connects two networks with different

technologies, and provides an intelligent means of transferring packets from one network to the other.

Also forwards traffic among multiple hubs and bridges.


Router Example



SessionSession

TransportTransport

PhysicalPhysical

NetworkNetwork

Data LinkData Link


PhysicalPhysical


SessionSession

TransportTransport

NetworkNetwork

Data LinkData Link

PhysicalPhysical

NetworkNetwork

Data LinkData Link

PhysicalPhysical

NetworkNetwork

Data LinkData Link

RouterRouter


Routing Switch

Operates at Layer 3, the network layer. Combines the intelligence of a router with the

efficiency of a switch, Routing data at higher speeds.


Gateway

Operates at Layer 7, the application layer. Can encompass all seven of the OSI model

layers. A computing system that can be programmed to

do any number of intricate protocol conversions and negotiations, such as between IP and IPX.



4. Network Management related Protocols

SNMPv1SNMPv2CICMPARP/RARPDHCP


SNMPv1 (Simple Network Management Protocol version 1)

The most common management protocol in use in data networks. Provides a means of obtaining information from, and sending

information to, network devices. Based on the manager-agent model. Uses Management Information Bases (MIBs) to exchange

information between the manager and the agent. Using the SNMP protocol, a manager can query and modify the

status and configuration information on each managed device by making requests to the agent running on the managed device.

All commands use the UDP/IP protocol, which means that communication between the manager and the agent is connectionless.

SNMP operates at Layer 7, the application layer.


SNMPv2C (version 2)

SNMPv2C includes the basic functions of SNMPv1. Adds

new message types, standardized multi-protocol support, enhanced security, new MIB objects, and a way to co-exist with SNMPv1.

SNMPv2C is useful for the retrieval of large amounts of management information using fewer network resources.


ICMP (Internet Control Message Protocol)

ICMP is the part of IP that handles error and control messages.

ICMP operates at Layer 3, the network layer. ICMP supports an echo function, which sends a packet

on a round-trip between two hosts. Ping, which sends a signal to see if an interface is up

and running, is based on ICMP echo. ICMP can also send an address mask request that

returns the address of the subnet mask on the remote system. This feature is important for non-SNMP devices.


ARP/RARP (Address Resolution Protocol / Reverse ARP)

ARP/RARP are used at Layer 2, the link layer, ARP is used to map an IP address to a MAC (or

link level, or hardware) address. RARP is used to map a MAC address to an IP

address.


DHCP(Dynamic Host Configuration Protocol)

DHCP allows IP addresses to be allocated on a temporary basis (a lease).

When the lease for an IP address expires, the address can be reused by a different node.

This is useful in environments supporting mobile users who connect to the network with a laptop from many different places.

This helps alleviate the problem of limited IP addresses and simplifies TCP/IP client configurations.

Documents

Network Elements and Services