Page 136 - DCAP307_PLANNING_AND_MANAGING_IT_INFRASTRUCTURE

Planning and Managing IT Infrastructure

Notes The mesh backbone includes over 30 nodes, all sharing a single radio channel. Broadband
Internet services are provided to all mesh members. The total upstream Internet bandwidth
available is 6 Mbps. There are over 2,000 computers connected to the mesh, the broadband
internet connection is putting the mesh under great load. At present, the system seems to
handle the load without any increase in latency or packet-loss. It is clear that scalability
will become an issue if we continue to use a single radio channel. To solve this problem,
new mesh routers with multiple radio channel support are being developed and tested in
Dharamsala, with an emphasis on products that meet our technical requirements and our
economically viable. The initial results are very promising.
The mesh network is based on recurring deployments of a hardware device, which is
designed and built locally – known as the Himalayan-Mesh-Router. The same mesh-
routers are installed at every location, with only different antennas, depending on the
geographical locations and needs. We use a wide range of antennas, from 8 - 11 dBi omni-
directional, to 12 - 24 dBi directional antennas and occasionally some high gain (and cost)
sector antennas.
The mesh is primarily used for:
1. Internet access
2. File-sharing applications

3. Off-site backups
4. Playback of high quality video from remote archives.
A central VoIP, software-based PBX is installed (Asterisk) and it provides advanced
telephony services to members. The Asterisk PBX is also interfacing the PSTN telephone
network. However, due to legal issues it is presently used only for incoming calls into the
mesh. Subscribers use a large variety of software-phones, as well as numerous ATAs
(Analog Telephone Adaptors) and full-featured IP phones.
The encrypted mesh back-bone does not allow access to roaming mobile devices (notebooks
and PDAs), so we have placed multiple 802.11b access points at many of the same locations
where mesh-routers are installed. The mesh provides the backbone infrastructure while
these APs provide access to mobile roaming devices, where needed.
Access to the mesh backbone is only possible by mesh-routers. Simple wireless clients
lack the intelligence needed to “speak” the mesh routing protocols and strict access policies.
The mesh channel is therefore encrypted (WPA), and also “hidden” to prevent mobile
devices from funding it or attempting to access it. Allowing access to the mesh only by
mesh-routers allows for strict access control policies and limitations to be enforced at the
Client Premises Equipment (CPE) which is a crucial element needed to achieve end-to-end
security, traffic-shaping, and quality-of-service.
Power consumption of the mesh-Router is less than 4 Watts. This makes them ideal for
using with solar panels. Many of the Dharamsala Mesh routers are powered solely by
small solar panels. The use of solar power in combination with small antennas and low
power routers is ideally suitable for disaster areas, as it very likely to survive when all
other communication infrastructure is damaged.

Questions
1. Discuss the results produced by extensive testing (for mesh networking) done during
February of 2005.

2. What is the use of mesh network? Discuss.
Source: http://wndw.net/pdf/wndw2-en/ch11-casestudies.pdf

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