A quick simple presentation about how a company needs to use the OSI Model to look at building their network. Power, Cabling, Routers, and Switches are the most important items to start with; they are the foundation of your companies infrastructure!

1. The Foundation presents
Third Thursday:
The Evolving Internet
and Your Business
May 17, 2007

2. Thanks to Dunwoody College
www.dunwoody.edu

3. Timeline
• 1992 - Email/FTP
• 1995 - Websites
• 1997 - Web browsing
• 1998 - Google
• 2002 - Intranet (SharePoint - 04-06)
• 2003 - Disaster Recovery Planning
• Broadband and High Bandwidth
• 2004 - VoIP

4. 2007 Maturing of Techs
• Virtualization
• Offsite
• DR
• Remote Backup
• ASP Models
• Online ERP apps
• Sharepont
• Large Pipes

5. The OSI Model
Data Application (telnet, http)
Data Presentation (e-mail, mime)
Data Session (named sockets)
Segments Transport (TCP, UDP)
Packets Network (IP, IPSec, ARP)
Frames Data Link (Ethernet, Fibre, 802.11g/n)
Bits Physical (hubs, 10-BaseT)

6. Where it’s at - Layers 1-3
Packets Network (IP, IPSec, ARP)
Frames Data Link (Ethernet, Fibre, 802.11g/n)
Bits Physical (hubs, 10-BaseT)
• Ethernet - Layers 1,2 - both
interface and transport
• Switches are at Layer 2
• Routers are at Layer 3

7. Switches
Frames Data Link (Ethernet, Fibre, 802.11g/n)

8. What is a switch, really?
• Larry’s definition: Creates one or many
independent networks, enables concurrent
communication at different speeds
• Focuses on the MAC address level
• Decides path for frames
• Allows full-duplexing - talking at the same time

9. Isn’t that just like a hub?
• A hub is a Layer 1 device
• Permits physical connection, but offers no traffic
discretion
• Traffic can be seen and/or collide from all ports
in any direction
• The ultimate in unmanaged networking

10. Types of switches
• Unmanaged - No configuration interface or
options
• Managed - Wide variety of configuration
options
• Smart - Limited version of managed switch
• Gigabit - Highest wire-based speed for
commercial applications. Highest collision
probability too!

11. What can I do with
a (good)switch?
• Use Ethernet, Fibre Channel, wireless
• Seamlessly traverse all of these mediums
• Set port priority
• Filter traffic per device
• Create VLAN’s (Virtual Local Access Networks)
• Use spanning trees to detect your network
construction
• Monitor links using SNMP
• Bonding/Trunking

12. Switches handle Frames
80 00 20 7A 3F 3E 80 00 20 20 3A AE 80 00
Destination MAC Address Source MAC Address EtherType
MAC Header
(14 bytes)
IP, ARP, etc.
Payload
Data
(46-1500 bytes)
00 20 20 3A
CRC Checksum (4 Bytes)
Ethernet Type III Frame
(64-1518 bytes)

13. Component parts of a Frame

14. Setting port priority
• Used in tandem with other policies to ensure quality of
service
• There is a business need for certain groups to have a
data priority
• Certain physical ports assigned to purposes greater than
others
• Best use: Bandwidth needed at all costs (VoIP, graphics
team)

15. Making a VLAN
• Used in tandem with other policies to ensure quality of
service
• Carves up the network into traffic groups
• Common uses: storage areas,VoIP
• Ports are tagged with a VLAN identifier across switches

16. A simple VLAN

17. Trunking
• Used in tandem with other policies to ensure quality of
service
• At the simplest level, allows you to bundle VLANs and
ports together - benefits of aggregation
• Focus on distribution of resources for optimal network
function

18. A simple trunk

19. Why are good switches
important?
• In combination with power and cabling, the basis of your
communication
• 80% of network failures occur in Layers 1-3
• Detection not possible on low-end switches
• Assuring quality connections becomes possible
• Can replace many other devices in a single management
center
• Port negotiation issues between vendors - code updates
across the board - standardization helps network
support as well.

20. Routers
Packets Network (IP, IPSec, ARP)

21. Routers are intersections

22. What is a router, really?
• Larry’s definition: A junction between one or
more networks
• Focuses on the IP address level
• Decides path for packets
• Edge or core: Home users are familiar with
edge routers that connect to the Internet, core
routers work within a network

23. What can I do with a router?
• NAT (Network address translation)
• Route IP traffic between different networks
• Move traffic between VLAN’s
• VPN (Virtual Private Network)

24. NAT explained
• Converts real world addresses to local addresses
• Acts as a natural firewall to prevent incoming requests
• Tracks destinations and ports - different NAT types
allow/restrict more heavily
• Problem services that must be addressed: FTP, IPSec
(VPN), VoIP

25. Route IP Between Networks
• Enables you to get from point A to point B. Even
though it’s often more like point A to point Z.
• A well-honed configuration table keeps paths well
defined.
• In smaller networks, an important traffic cop for
intelligent handling of communication

26. 1 Destination - 11 hops
Example of IP routing
1 10.55.93.1 (10.55.93.1) 2.142 ms 2.445 ms 4.400 ms
2 71.5.110.1 (71.5.110.1) 117.125 ms 122.690 ms 120.718 ms
3 71.5.107.161 (71.5.107.161) 123.949 ms 134.323 ms 130.106 ms
4 67.109.64.93.ptr.us.xo.net (67.109.64.93) 127.231 ms 139.356 ms
144.822 ms
5 p6-3-0-0.mar2.chicago-il.us.xo.net (207.88.84.61) 159.507 ms 149.822 ms
6 p4-2-0-0.rar2.chicago-il.us.xo.net (65.106.6.205) 168.493 ms 164.606 ms
7 p1-0.ir1.chicago2-il.us.xo.net (65.106.6.138) 169.688 ms 182.233 ms
8 206.111.2.14.ptr.us.xo.net (206.111.2.14) 244.645 ms 342.918 ms
9 yahoo-4.ar2.dca3.gblx.net (64.208.110.122) 227.710 ms 214.968 ms
10 ge-1-0-0-p110.msr2.dcn.yahoo.com (216.115.108.45) 231.577 ms ge-1-0-0-
p100.msr1.dcn.yahoo.com (216.115.108.41) 111.548 ms 140.541 ms
11 ge3-1.bas1-m.dcn.yahoo.com (216.109.120.149) 151.243 ms ge10-2.bas2-
m.dcn.yahoo.com (216.109.120.249) 186.563 ms ge7-2.bas1-m.dcn.yahoo.com
(216.109.120.201) 197.609 ms

27. Intra-VLAN Routing

28. VPN
• Router acts a traffic cop as always
• Defines and limits access to certain areas on local
network from outside
• Builds a bridge from outside/inside or from network
to network
• If you’re on a pleasure trip, take a ferry. If you’re on
mission, you need a submarine.
• Replaces/augements leased lines (i.e., dedicated T1)

29. Big World VPN

30. Why do I need a decent router?
• What’s better than having a traffic light? An intelligent
cop at every corner
• 80% of network failures occur in Layers 1-3
• Today’s routers are like mini-computers, running
programs, encrypting traffic, etc.
• Working with decent switches, networks can gain
complexity and maintain their zip
• Business needs: secure private connections, FTP, mail
servers, wireless

31. The Big Picture
• The basis of your business begins at power
• How you connect to that power (your wires)
• What interfaces your wires use to get to your desktop
(routers and switches)
• Using this model start at layer one and work up
• Big companies and small alike build mansions on dirt
roads
• Pick a single vendor and save yourself trouble

32. THE FOUNDATION
311 7th Avenue North Mpls, MN
612-465-0700
www.fndtn.com