Transcript Spanning Tree

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 hubs
repeaters
transceivers
cabling
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 hub
PC to switch
PC to hub
Cross-over (like interfaces)
switch to switch
hub to hub
switch to hub
PC to PC
Rollover
Console into router
What happens when you use
the wrong cable?
???????
Testing cables
Using a cable tester
http://www.flukenetworks.com/fnet/enus/products/MicroScanner+2/Overview.htm?categor
ycode=CPTT
Fiber
Multimode fiber – Supports up to 10Gbps (10 Gig)
Up to 550Meters
Used commonly to interconnect wiring closets or
buildings
Single mode fiber – Supports up to 10Gbps (10 Gig)
Up to 60 Kilometers
Used 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
Devices
switch
bridge
How do you find the MAC
Address?
Windows
1. Click Start
2. Run
3. cmd
4. ipconfig/all
Mac
1. Open up a terminal
2. 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)
Devices
router
layer 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