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How To Build a Redundant, Fault
Tolerant, Load Balanced, Traffic
Managed Wireless network
a bella mia company
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, P15.
Located in South East Wisconsin
So you are a Wireless ISP
But how do you make your
system Redundant?
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.
Assuming you have all that,
lets take a look at how things
break down.
Break down of Redundant WPOP Setup
NOC
Your Network Operations Center
Connected to multiple Providers
Running BGP
WPOP 1
Your Wireless POP/Tower
Land line from your NOC
Cisco Router
PTP
Wireless Link to Tower 2
Cisco Router
Bandwidth Manager
WPOP 2
Your other Wireless POP/Tower
Land Line from your NOC
Cisco Router
PTP
Wireless Link to Tower 1
Lets Start at the WPOP
• 3 180 degree
Sectors
• 3 runs of Heliax
• 4 Access Points
• Cisco Router
• UPS
• Switch
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
The Big Picture
Wireless PTP
WPOP 2
WPOP 1
T1 or Wireless or both
T1 or Wireless
Bandwidth Manager
Internet
Router
NOC
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)
Another Key Point!
Maintenanc
e!
_ Imagine Near Zero Down Time
• Easily add to existing infrastructure
• Upgrade Remote Devices
• Replace Downed Gear
But does it Work?
Well Let’s See it in Action!
Some Examples
WPOP 1 Aggregate
Traffic
WPOP 2 Aggregate
Traffic
Traffic Flow over PTP between WPOP 1 & WPOP
2
What does it look like when a
pipe goes down?
PTP under normal
PTP with 1 Link Down
conditions
• 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
Where do you go from here?
Endless Expansion!
Wireless PTP
WPOP 3
Wireless PTP
WPOP 1
Wireless PTP
WPOP
2
T1
T1
Bandwidth Manager
Wireless PTP to NOC
Internet
WPOP 4
Router
NOC
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
OSPF
• Open Shortest Path First
• Allows for redundancy
• Smarter routing of traffic
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
Example of SPF: Mapping
How does OSPF fit in?
Cost = 96
Wireless PTP
WPOP 1
T1
T1
Cost = 64
WPOP 2
Cost = 64
Bandwidth Manager
Internet
Router
NOC
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
Sample Cisco router config
interface Ethernet0
ip address 10.0.0.1 255.255.255.0 ! Just an example
ip ospf message-digest key 1 md5 <Put OSPF password
ip ospf cost 96
exit
interface Serial0
ip address 10.0.1.1 255.255.255.0 ! Just an example
ip ospf message-digest key 1 md5 <Put OSPF password
exit
router ospf 100
redistribute connected subnets
redistribute static subnets
network 10.0.0.1 0.0.0.0 area 0
network 10.0.1.1 0.0.0.0 area 0
default-information originate always
area 0 authentication message-digest
ospf log-adjacency-changes
exit
ip address
here>
ip address
here>
OSPF in a larger network
Cost = 10
Wireless PTP
WPOP 3
Cost = 96
Wireless PTP
WPOP 1
Cost = 10
Wireless PTP
Cost = 64 Cost = 64
T1
WPOP
2
T1
Bandwidth Manager
Wireless PTP to NOC
Cost = 63
Internet
WPOP 4
Router
NOC
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
Questions?
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:
http://wispconvi.mia.net/ppt/keeping-it-up.ppt
You can contact me via email with further questions at:
[email protected]
www.wisconsinwireless.net
a bella mia company
Copyright 2004 bella mia, inc