Networking Essentials Notes
CAT 1 – Voice only
CAT 2 – 4 Mbps
CAT 3 – 10 Mbps
CAT 4 – 16 Mbps
CAT 5 – 100 Mbps
Thinnet (10base2) – 185 meters (607 feet) – 10 Mbps -- BNC Connector (barrel connector, terminator), RG58 cable. 5-4-3 rule (5 segments with 4 repeaters but only 3segments can have computers.)
Thicknet also known as Standard Ethernet (10base5) – 500 meters (1640 feet) – 10 Mbps – AUI (attachment unit interface) connector, transceivers, transceiver cables (connect to thin),
Twisted Pair (10baseT) – 100 meters (328 feet) – 4-100 Mbps – RJ 45 connector
90% of new installs are UTP Star.
Fiber Optic -- 2 kilometers (6562 feet) – 100 Mbps or more
10BaseFL – (2000 meters) Fiber Optic - expensive and hard to work with.
100BaseX= Fast Ethernet.
Full Duplex - data going in both directions at the same time.
Half Duplex - data going in both directions, one direction at a time.
Simplex - data going in one direction only.
STAR BUS LINEAR BUS STAR
10BaseT 10Base2 100BaseVG AnyLAN
100BaseX 10Base5
MESH – common WAN topology – remote sites over multiple communications lines. Routers determine best path.
IRQ’s
2(9) EGA/VGA
3 Available (or COM2,COM4)
4 COM 1, COM 3
5 Available (unless LPT2 or sound card)
6 Floppy Disk Controller
7 Parallel port (LPT1)
8 Real-time clock
10 Available
11 Available
12 Mouse (PS/2)
13 Math Coprocessor
14 Hard-disk controller
- Available
OPEN SYSTEMS INTERCONNECTION MODEL
APPLICATION – software (what you see on screen)
PRESENTATION – translation, compression
SESSION – security and name recognition to allow applications to communicate.
TRANSPORT – insures packets are delivered error free. (flow control, error handling)
NETWORK – addressing messages and translating logical addresses into physical addresses.
DATA LINK – packages bits into data frames (includes control & CRC)
PHYSICAL – electrical, optical, mechanical.
Data Link breaks down into MAC Layer and Logical Link Control Layer
Logical Link Control handles error and flow control
MAC Layer handles access control.
802 Network Model – Defines Network standard for the physical part of the network.
802.3 – CSMA/CD – LAN Ethernet
802.5 – Token Ring - LAN Token Ring
BASEBAND – digital over single frequency
BROADBAND – analog signal over a range of frequencies, nondiscrete unidirectional signal.
NetBIOS is not a protocol – it is a standard for programming. (15 character naming convention.)
Protocols are binded to the network card.
NDIS 3.0 – allows for multiple protocols to bind.
Network Protocol – find you and deliver data.
Transport Protocol – get data to you error free.
PROTOCOLS
DLC – non-routable - used for HP Printers (Jet Direct) and IBM Mainframe Connectivity.
NetBEUI – non-routable – NetBIOS extended user interface (Microsoft Networks only.)
IPX/SPX – Novell – similar to NetBEUI, only routable.
NWLINK – Microsoft version of IPX/SPX.
TCP/IP – routable – used for Internet
X.25 – Routable – used in a switching network.
XNS – Routable – used in Xerox’s Ethernet LANs before TCP/IP.
APPC - non-routable – IBM’s transport protocol (part of SNA)
Apple Talk – Routable – Apples Protocol Stack.
OSI protocol Suite – Routable – each protocol maps directly to a layer of the OSI model.
DECnet – Routable – Digital’s protocol stack – implements the DNA (Digital network architecture).
Contention – competition among stations to use a network resource or communications line.
Redirector – All Microsoft products come with a redirector that takes request from the computer and looks to see if it is local or sends to network.
PPP – Point to Point Protocol – used with dial-up adapters. Can automatically configure IP addresses.
Point to point serial communication using TCP/IP.
SLIP (Serial Line Internet Protocol) – must manually configure IP address. Must know both yours and the one you are connecting to. Point to point serial communication using TCP/IP.
NT DOMAIN
HCL – Hardware Compatibility List – lists all hardware that is compatible with Windows NT.
PDC - Primary Domain Controller – Logins, Permissions, Scripts, Securities.
BDC - Backup Domain Controller – a computer that receives a copy of the domain’s security policy and database and authenticates network logons. (It provides a backup in case the PDC becomes unavailable. It is not required but is recommended to be a backup to the PDC.
NT allows you to decide who can and can not print.
NT Service is an application that allows you to add services MAC Service (need service to be able to connect to other OS’s).
Fax Server – manual routing – physically check faxes and forward as E-mail attachments.
OCR reader converts fax into text for use.
DID (direct inward dialing) – special phone line that forwards faxes to appropriate person.
SMTP - works at top three layers of OSI model
GroupWare – interactive real time activities i.e. (bulletin boards databases.). Allows many people to work on one thing at the same time. Works on a variety of platforms.
Replication – mates two databases and only updates changes.
Multivendor Environments – enables different OS’s to talk to server.
Centralized Computing – terminal based computing.
Client/Server (front end/back end)
SQL – Structured Query Language – used by most databases to manipulate data.
Managing Network Accounts
User administration – creates and maintains accounts and access.
Resource management – implement and support network resources.
Configuration management – Planning original configuration, expanding and maintaining configuration info.
Performance Management – Monitor and track network activity to maintain and enhance performance.
Maintenance – prevents, detect and solve problems.
User manager for domains –used to create user accounts.
Restrictions – login times, home directory access only, account expiration.
Profiles – administrator account first, then guests.
GROUPS
Global
– created on PDC containing user accounts only from their own domain account database.Local – individual user accounts have rights and permissions on local computers.
Special – used for internal system access to resources and permissions.
Built-in – perform common network admin and maintenance tasks.
NT workstation to Novell Network
NWLINK & Client service for NetWare (CSNW)
CSNW is Microsoft’s version of NetWare’s requestor
NT server based server to NetWare network
NWLINK & Gateway service for NetWare (GSNW)
Windows 95 Client to Novell Network
IPX/SPX & Microsoft client for NetWare.
Microsoft service for NetWare Directory Services (NDS)
Incorporates support for Novell 4.x
Diagnostic Tools
TDR – (Time Domain Reflectometer) – sends pulses down cable. Looks for shorts or opens. Can give you area of problem.
DVM - (Digital VoltMeter) – uses voltage, tests for continuity or short.
Protocol Analyzer – (sniffer) – monitors and logs network activities and provides guidelines for optimizing. Works at packet level.
Windows NT Performance Monitor –
Works in both real and recorded time.
Monitors processors, hard disks, memory, Network Utilization, Network as a whole.
Establish a baseline and compare from there.
SNMP (Simple Network Management Protocol) –
Part of TCP/IP Suite – programs called agents monitor network traffic and behavior.
Store data in MIB’s (management information database)
Records hubs, servers, NIC’s, routers.
Sends an ALERT to Network Manager If beyond certain ranges.
SMS (Systems Management Server) Microsoft’s back office product allows you to monitor systems. Works with NT server only. Desktop management, Remote Control, software distribution, Inventory management (hardware and software data).
Network Data Security
Password Protected Share (share level security) – assign password to each shared resource
Access Permissions (user level security) – user enters a logon and password at login and server checks a database and assigns security as applicable. Resources are controlled by the administrator and are allowed to the user at login.
C2 compliant – Govt. level of security
Virus checks, passwords, access rights
Avoiding Data Loss
Tape Backups – cheapest backup method, be sure to test!
UPS (uninterruptible power supply) – power supply to run the server for a short time in case of power loss.
RAID (redundant array of inexpensive disks) – Fault Tolerance
RAID is handled through NT’s disk administrator. (Supports 1&5)
Level 0 – Disk Striping – divides data into 64K blocks and distributes evenly among all disks in an array. Provides no redundancy or fault tolerance.
Level 1 – Disk Mirroring – Write all data to two hard drives in sync, if one fails then swap.
Level 5 – Disk Striping with Parity – supports three to 32 hard drives. Allocate same amount of space on each hard drive. Divides data into 64K blocks and writes parity info evenly among all disks in an array. If one disk fails, enough parity info is written across other disks to recreate it. Parity stripe block is used to reconstruct data.
MODEMS – converts digital PC signal to analog phone signal and back. Uses sound waves to transmit data. Telephone lines have a 33,600 Kbps max speed.
Asynchronous – a start and stop bit is added to the data(and
parity
bit)to provide data synchornisation
Synchronous – a clocking signal is supplied to provide data Network Devices –
synchronisation
RAS - (Remote Access Services) – NT can handle up to 256 calls.
Repeaters – work at the physical layer – regenerates a signal – can send from thinnet to Fiber… broadcasts all transmissions.
Bridges – work at data link layer – isolate different segments – link unlike segments such as Ethernet and Token Ring – can reduce network traffic by routing across its own segment instead of across the network. Reads source and destination of every packet. Broadcasts all transmissions.
Routers – work at network layer (IP & IPX)
Uses routing table to determine where IP address goes. Uses network part of IP address.
Hop – every time you change to a different router.
OSPF – open shortest path first (routing algorithm)
RIP – routing information protocol – uses distance-vector algorithms to determine routes.
Static router – administrator manually sets up and configures routing table.
Dynamic Router – automatically track routes. Routers talk to routers and add them to the tables.
Bridge uses MAC address, Router uses network address.
Brouters
– combination of both.GATEWAYS
– work at all layers.Gateways change format of the data to make it conform to the application program at the receiving end.
Strips packet and rebuilds with new protocol info
I.e. PC connectivity to mainframe. Gateway strips PC packet and rebuilds it in mainframe form.
Proxy server is gateway to the Internet.
Analog phone lines can’t carry voice and data simultaneously.
Digital Lines
T1 – 1.544 Mbps – point to point full duplex transmission. Voice, data and video.
T3 – 45 Mbps– point to point full duplex transmission. Voice, data and video
Switch56 – 56Kbps – digital dialup uses CSU/DSU
Packet switching networks
Packets are sent over different routes to a destination to speed up delivery.
Virtual Circuits – logical connections between sending and receiving computers.
SVC – switched virtual circuit
PVC – Permanent virtual circuit
Sending DATA across a WAN
X.25 protocol – incorporated into packet switching network. Uses PAD. – Packet switching protocol.
PAD – packet assembler/disassembler – receives asynchronous characters from terminals and assembles into packets to be transmitted over network and back.
Frame Relay – point to point system – uses PVC – fast packet, variable length digital – digital leased lines. Provides bandwidth as needed. – Packet switching protocol
ATM – asynchronous transfer mode – fixed packets – broadband.
Speeds up to 622 Mbps – used mainly for ISP backbones because of cost.
53 byte cells instead of packets. – Packet switching protocol
ISDN – integrated services digital network
128 bits per second – 2B+D – 2 64Kbps B channels & 1 16Kbps D channel.
Voice, data, images - signaling&link mgmt. Data
FDDI – Fiber Distributed Data Interface 100Mbps
Used mainly for MAN technology – works in a double ring.
Like Token-Ring only many frames can go on the token, not just one.
SONET – synchronous Optical Network – fiber-optic – 1 Gig per second
SMDS – switched multimegabit data service. Up to 34 Mbps
Same fixed length cell relay technology as ATM.
©2000 www.CERTguide.com