1. KEEPING IT UP
How To Build a Redundant, Fault Tolerant, Load Balanced, Traffic Managed Wireless network
a bella mia company

2. A Little Background Jeremy Kinsey or“Jer” to his friends.
CEO and Co-Founder of Bella Mia, Inc.
Been an ISP for 8 years
Been a WISP for 4 years
Part-15 WISP of the Year WISPCON III
Part-15 Member
Regular Speaker at WISPCON, WCA, P-15.
Located in South East Wisconsin

3. So you are a Wireless ISP But how do you make your system Redundant?

4. Some Assumptions
You have at least 2 WPOPS (Wireless Points of Presence)
You already have a redundant network, ie., are running BGP, have two providers, etc.
You have a good understanding of Cisco Routers and various routing protocols.

5. Assuming you have all that, lets take a look at how things break down.

6. Lets Start at the WPOP 3 180 degree Sectors 3 runs of Heliax
4 Access Points
Cisco Router
UPS
Switch

7. Where do the pieces fit? One Sector per side of tower
One Radio per sector
UPS, Radio, Switch, Router in enclosure at tower base.
Router Wired and or Wireless Link to NOC

8. The Big Picture Wireless PTP WPOP 2 WPOP 1 NOC Internet
T1 or Wireless or both
T1 or Wireless
Bandwidth Manager
Internet
Router
NOC

9. So what do we have?
Redundancy at the WPOP (multiple separate radios & antennas)
Redundancy in the entire system (multiple paths, using multiple technologies, traffic re-routed on the fly)
Shared bandwidth (load balanced traffic, and bandwidth delivered where it is needed on demand)

10. Maintenance! Another Key Point! _ Imagine Near Zero Down Time
Easily add to existing infrastructure
Upgrade Remote Devices
Replace Downed Gear

11. Well Let’s See it in Action!
But does it Work?
Well Let’s See it in Action!

12. Some Examples WPOP 1 Aggregate Traffic WPOP 2 Aggregate Traffic
Traffic Flow over PTP between WPOP 1 & WPOP 2

13. What does it look like when a pipe goes down?
PTP under normal conditions
PTP with 1 Link Down
1 Pipe goes down, traffic automatically re-routed over backup link
Pipe comes back up, PTP traffic will return to normal
Your users never know what happened

14. Where do you go from here?

15. Endless Expansion! Wireless PTP Wireless PTP Wireless PTP
WPOP 3
WPOP 1
WPOP 2
Wireless PTP T1 T1
Bandwidth Manager
Wireless PTP to NOC
Internet
WPOP 4
Router
NOC

16. So How Do I Do It?
Now for the routing side of the “Keeping It Up”session
Josh Easton, CTO Bella Mia, Inc.
Routing protocols used and why

17. OSPF Open Shortest Path First Allows for redundancy
Smarter routing of traffic

18. Brief intro to OSPF Every network link (T1, ethernet, etc.) has a cost
When multiple paths are available, lowest cost path is chosen
Total cost of a path is the sum of the costs of each segment
Costs can be manipulated to route your traffic ideally

19. Example of SPF: Mapping

20. How does OSPF fit in? Cost = 96 Wireless PTP WPOP 2 WPOP 1 Cost = 64
Bandwidth Manager
Internet
Router
NOC

21. Why these costs? T1 has a default cost of 64
Wireless link is manually set at cost of 96
Traffic from WPOP1 to WPOP2 will take the wireless PTP link if it’s available, else it will use T1s
Traffic from WPOP1 to Internet goes via the local T1, else via the wireless PTP link to WPOP2 and then via WPOP2’s T1

22. Sample Cisco router config
interface Ethernet0
ip address ! Just an example ip address
ip ospf message-digest key 1 md5 <Put OSPF password here>
ip ospf cost 96
exit
interface Serial0
ip address ! Just an example ip address
router ospf 100
redistribute connected subnets
redistribute static subnets
network area 0
network area 0
default-information originate always
area 0 authentication message-digest
ospf log-adjacency-changes

23. OSPF in a larger network
Cost = 10
Cost = 96
Wireless PTP
Wireless PTP
WPOP 3
WPOP 1
WPOP 2
Cost = 10
Cost = 64
Cost = 64
Wireless PTP T1 T1
Bandwidth Manager
Wireless PTP to NOC
Cost = 63
Internet
WPOP 4
Router
NOC

24. Why these costs? Cost from WPOP4 to NOC is manually set at 63
Traffic from one WPOP to another WPOP will use the wireless backbone by default
WPOP3 and WPOP4 use WPOP4’s link to the NOC to get on the Internet
WPOP1 and WPOP2 use their T1s to get on the Internet
If any link goes down, traffic will be routed around the damage

25. Questions? www.wisconsinwireless.net Thank you for your attention!
Presentation presented and created by
Jeremy Kinsey and Josh Easton
Thank you for your attention!
A PPT copy of the presentation can also be found online at:
You can contact me via with further questions at:
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Copyright 2004 bella mia, inc.