making routers last longer with viaggre hitesh ballani, paul francis, tuan cao and jia wang cornell...
Post on 19-Dec-2015
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Making Routers Last Longer with ViAggre
Hitesh Ballani, Paul Francis, Tuan Cao and Jia Wang
Cornell University and AT&T Labs-Research
Presented by Gregory Peaker, Zhen Qin
Outline• Motivation• ViAggre design• Allocating aggregation points• Evaluation• Deployment• Discussion
Motivation
• Large Routing Table More FIB space on Routers
• Rapid future growth IPv4 exhaustion IPv6 deployment
Does FIB Size Matter?• Technical concerns
Power and Heat dissipation problems• Business concerns
Large routing table Less cost-effective networks
Price per bit forwarded increases
Cost of router memory upgrades
ISPs are willing to undergo some pain to extend the life of their routers
Allocating aggregation points• A router’s FIB size (Fr):
• routes to the real prefixes in the virtual prefixes it is aggregating
• routes to all the virtual prefixes• routes to the popular prefixes• LSP mappings for external routers
Allocating aggregation points• Traffic stretch:
• packets from router i to prefix p belonging to a virtual prefix v are routed through router k
• j is the egress-router for a traffic from router k to prefix p• i chooses k as an aggregation point that is closest in terms
of IGP metrics, where k is also belonging to virtual prefix v
Allocating aggregation points• Definition of can_server
• If router i were to aggregate virtual prefix v, which routers can it serve without violating the stretch constraint C.
• In accordance with can_server relation while trying to minimize the worst FIB size, an algorithm was proposed to designate all routers are served for a virtual prefix
Evaluation• Impact on Traffic
– Traffic stretched using different router level path than native path
• Increase Router Load
Evaluation using ISPs• Tier 1
– Extend life of routers from 2007 to 2018– 39% increase load on routers– 1.5% of prefixes for 75.5% traffic– 5% of prefixes for 90.2% traffic
Evaluation using ISPs• Tier 2
– Apply routing table for their customers– Use default table for all other customers
• Negligible traffic stretch (<0.2 msec)• Negligible Increase in Load (<1.5%)
Deployment• Can be incrementally deployed• Can be deployed on small scale• Incentive for deployment• No Change to ISP’s routing table
– Does not affect routers advertised to neighbors
– Does not restrict routing policies
• Extra configuration– Could be automated
• Vendor support + cheaper routers
Conclusion & Offense• Can be used by ISPs today• 10x reduction in FIB size• Negligible traffic stretch• Negligible load increase• ISPs extend lifetime of routers• A simple and effective first step