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, P- 15. 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.

Lets Start at the WPOP 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 Internet NOC Router Bandwidth Manager WPOP 1 WPOP 2 T1 or Wireless or both T1 or Wireless Wireless PTP

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! _ Imagine Near Zero Down Time Easily add to existing infrastructure Upgrade Remote Devices Replace Downed Gear Maintenanc e !

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? 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 PTP under normal conditions PTP with 1 Link Down

Where do you go from here?

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

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? Internet NOC Router Bandwidth Manager WPOP 1 WPOP 2 T1 Wireless PTP Cost = 64 Cost = 96

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 ! Just an example ip address ip ospf message-digest key 1 md5 ip ospf cost 96 exit interface Serial0 ip address ! Just an example ip address ip ospf message-digest key 1 md5 exit 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 exit

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

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? Copyright 2005 bella mia, inc. Presentation presented and created by Jeremy Kinsey and Josh Easton a bella mia company 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: