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