OSPF for Broadband Wireless Campus Backbone

Joseph Hui

ISS Chair Professor and Director,

Telecommunications Research Center

Arizona State University

Talk Outline

• Applications for Wireless Broadband Campus Networks

• Optical versus Radio Frequency

• OSPF for Broadband Wireless Networks

• On-going embedded system prototype.

Applications of Broadband Wireless Backbone

• Large data storage facilities scattered on campus

• Growing need for multimedia educational material storage/retrieval

• Digital/video libraries

• Massive data stores (Mars Probe, 3D models)

• Wireless LAN hot spots

• Portable wireless multimedia booths?

ASU Campus Backbone

• Hub and Spoke Gigabit Ethernet.• Three level hierarchical network• East-Central-West Campus• A few isolated, off-campus buildings• Want: Scalable and reconfigurable networks• Solutions:

– Wireless broadband– Distributed Storage Area Networks– Reliable OSPF protocol for wireless links

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Proposed Broadband Wireless Network Topology

• An adjunct broadband wireless network• Mesh/Ring network for the second tier hubs• Mesh/relay network for third tier nodes

Optical versus Radio Networks

• Advantages of optics:– No spectrum licensing

– No multipath problems

– Cheaper/smaller transceivers

– high speed/DWDM

– Excellent channel isolation

– Security

• Advantages of radio:– LOS not mandatory

– Longer distances

– More weather resistant

– Less background noise

– Ease of pointing

– Eye safe

Going Optical

Wireless Campus Network

• Current approaches– LMDS for WLL, not

backbone

– Hub architecture

– Shared bandwidth

– LEC model

– DSL over ATM

• Proposed Approach:– Totally wireless backbone, no

distinguishable local loops.

– Mesh architecture

– Multiple parallel paths

– Internet model

– {SCSI,FC,10xBaseT,TCP,IB} over IP

Key Challenges• Optical links

– propagation, pointing, power budget, eye safety

• Data links

– link/node failure, traffic measurements, QoS control

• Network routing/management

– Ad-hoc routing, IP switching, resource discovery, traffic balancing, domain management

• System Analysis

– Interface interoperability, multiple protocols, device mapping/configurations.

Network Types

• Meshed Networks– Fully Meshed (Each

and every node is connected to all others by no more than one hop)

– Partially Meshed (A node may be connected to other nodes by more than one hop)

• Fragile Networks– Any link of the

network may become inoperative at any time. The failure of a single link should not prohibit message delivery

The Effect of Fragility(Providing A High Availability Environment)

1. Router Failure

2. CPE Failure

3. Premise Link Failure

4. Link Failure

Protocols for Wireless Optical Ad-Hoc Networks

1. Link-state monitoring

2. QoS provisioning

3. Rapid yet distributed rerouting upon link/node failure

4. Resource discovery and management

5. Multi-protocol adaptations

Reliable IP based on OSPF

• OSPF is the predominant IP protocol for

– Intra-domain, distributed, link-state based routing

– Problem: rerouting require broadcast of link-state

• To make OSPF reliable

– QoS control based on DiffServ, TOS queue scheduling

– Pre-compute multiple paths based on QoS and link failure

– Rapid switch over to source routing if link or node fails

• Problem: Is it possible to retain much of OSPF distributed computation, yet able to route correctly when link/node fails?

Reliable IP based on OSPF

• Answer is Yes!

• Multipath OSPF with IP-encapsulation for source routing

• Node broadcasts link state infrequently

– Each node compute multiple paths contingent on fault/QoS

– Multiple IP for QoS assignments

– Use of IP encapsulation to forward packets along precomputed path.

Experimental Prototypes

• The Existing Project– Pizza box Router for Network Edge use based on IP– Free Space Laser Link at 850 nm and 1Gb/s– Millimeter Wave RF Link at 57-64 GHz and 1 Gb/s

• Applied both indoor and outdoor

Conclusion

• Distributed Router Development

– Protocol (Reliable IP)

– QoS Routing and QoS Link Management

– Network Management (IP encapsulation)

– Mirroring and Multicasting

• Four link implementations at 1 GHz

– Free Space Laser

– Wireless Millimeter Wave

– Fiber optic

– Copper

• Currently soliciting public and private funding for prototype