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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 “Known as Jer” to his
friends.
• CEO and Co-Founder of Bella Mia, Inc.
• Been an ISP for 6 years
• Been a WISP for 2 + years
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 Linke to Tower 1
Lets Start at the WPOP
• 3 180 degree
Sectors
• 3 runs of Heliax
• 4 radios Proxim
COR’s
• Cisco 1600 Series
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 connected to
T1 and NOC
The Big Picture
Wireless PTP
WPOP 1
T1
WPOP 2
T1
Bandwidth Manager
Internet
Router
NOC
So what do we have?
Redundancy at the
WPOP (3 separate radios
& antennas)
Redundancy in the
entire system (multiple
paths, 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 T1 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
• Costs can be manipulated to route your
traffic ideally
How does OSPF fit in?
Cost = 10
Wireless PTP
WPOP 1
T1
Cost = 64
T1
WPOP 2
Cost = 64
Bandwidth Manager
Internet
Router
NOC
Why these costs?
• T1 has a default cost of 64
• 10Mbit ethernet’s default cost is 10
• 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
• Note: Need IP+ image to do OSPF on 1600
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
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 = 45
Wireless PTP
WPOP 3
Cost = 10
Wireless PTP
WPOP 1
Cost = 10
Wireless PTP
Cost = 64 Cost = 64
T1
WPOP
2
T1
Bandwidth Manager
Wireless PTP to NOC
Cost = 10
Internet
WPOP 4
Router
NOC
Why these costs?
• Cost from WPOP1 to WPOP3 is manually set
at 45
• 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?
bella mia, inc - mia.net
“Keeping it Up”
by
Jeremy Anthony Kinsey
CEO bella mia, inc.
Josh Easton
CTO bella mia, inc
www.dslone.com
www.wisconsinwireless.net
Copyright 2002 bella mia, inc