Sysops Network Training

by Brett Haffener

Introductions

- Name

- School

- What are you most interested in learning about?

Where do we start?

OSI Model

- Breaks up networking into smaller parts

OSI stands for (Open Systems Interconnection)

Taken from:en.wikipedia.org/wiki/OSI_Model

Layer 1 (Physical layer)

Media & Signalling

Devices include -

hubsrepeaterstransceiverscabling

Ethernet Cabling Standards

Categories of copper cabling:

Category 5: Limited to 100Mbps

Category 5e: Up to 1000Mbps (Gigabit)

Category 6: Up to 1000 Mbps

All three are limited to 100M (328ft) in length from end device to end device

Gig vs. 100Mbps

Backbone and server connections would be best at Gig

What category cabling should you use?

I recommend Cat6

Costs 20 - 40% more

Prepares you for the future

80-90% of new copper installs are now Cat6

Less interference between cables, so there are fewer errors causing fewer resent packets (slightly faster performance)

Types of cables

Straight through

Crossover

Rollover

Straight-through

Cross-over

Rollover

Where do I use each cable?

Straight through (unlike interfaces)router to switch router to hubPC to switch PC to hub

Cross-over (like interfaces)switch to switch hub to hubswitch to hub PC to PC

RolloverConsole into router

What happens when you use the wrong cable?

???????

Testing cables

Using a cable tester

http://www.flukenetworks.com/fnet/en-us/products/MicroScanner+2/Overview.htm?categorycode=CPTT

Fiber

Multimode fiber – Supports up to 10Gbps (10 Gig)Up to 550MetersUsed commonly to interconnect wiring closets or

buildings

Single mode fiber – Supports up to 10Gbps (10 Gig)Up to 60 KilometersUsed to connect geographically distant locations(not as common in schools)

Network Topology

Recommend extended star *** many schools daisy chain their switches ***

Layer 2 (Data-link layer)

Physical addressing

Switching

Devicesswitchbridge

How do you find the MAC Address?

Windows1. Click Start2. Run3. cmd4. ipconfig/all

Mac1. Open up a terminal2. Type ifconfig

Two parts to the MAC Address

XX – XX – XX – XX – XX - XX

Matching an OUI with a company

http://coffer.com/mac_find/

Tracking down a problem with the MAC Address

If you don't know where a machine is located you can use the MAC address to track it down (if you have managed switches)

Loops in the network

Loops are formed whenever there are redundant links in the network

Traffic continues around the loop generating excess traffic

Can cause broadcast storms (drastically reducing performance)

Spanning Tree

Spanning tree protocol prevents loops from occurring by blocking traffic on the extra interface

(Enabling spanning tree)

Spanning Tree (pros & cons)

Pros – If there is a loop in your network it won't take the entire network down

Cons – In the past Spanning Tree has slowed Mac logins down- If there is a loop in your network you may not know about it if you don't check your switches

*** Recommend using “Rapid Spanning Tree Protocol” if you are going to use this ***

Hubs vs. Switches

The major difference between hubs and switches is that hubs broadcast traffic out all interfaces whereas switches only sent unicast traffic out the destined interface

Speed & Duplex settings

Mismatched settings often times causes errors

Best to hard set connections between network devices when possible

Best to leave connections to workstations and servers in auto-negotiate (in general)

Layer 3

Logical addressing (IP addressing)

Devicesrouterlayer 3 switch

How routing works

Packet Tracer

Firewalls and port openings

The main place where you'll have to worry about ports being opened is in your firewall

Using netstat to see open ports

From the command line type:

Netstat -a

Wireless testing

http://www.netstumbler.com/

http://www.macstumbler.com/

Wireless security

Recommend WPA2

Public & Private wireless network

Troubleshooting tools

Ping

Traceroute

NSLOOKUP

Troubleshooting DNS

From a command prompt or terminal you can type nslookup <URL>

If you think you are having DNS issues you can try going to the IP address instead