Scalability & Stability of the Internet Infrastructure. Farnam Jahanian Department of EECS University of Michigan <[email protected]>. Context. Routers. Name Servers. Critical Services. LIGHTHOUSE: Survivable Network Infrastructure. Network Infrastructure. Protocol Scrubbers.
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Department of EECS
University of Michigan
Joint projects between U. Michigan & Merit Network
Collapse of the Internet
Explosive growth in both size and topological complexity
Hierarchical network with a single central backbone
C3Internet Evolution: Today
Full-mesh interconnection of ISP backbones and customers
Deployed probes machines at five public exchange points
Collected all routing updates at IXPs over four year period
Linear growth in routing table
ISP Geeks Release
Sigcomm '97 findings were puzzling:
Bandwidth Utilization Instability
BGP-level timers expire, causing termination
Interaction between BGP and TCP leads to router congestion collapse
High bandwidth utilization BGP Instability
Validated using Windmill tool (SIGCOMM98)BGP Congestion Collapse Hypothesis
Fault Injection Server
each ISP following a routing update event
After a BGP route is withdrawn, barring other failures, how long does it take Internet routing tables to reach steady-state?
Convergence delay after a Tdown
What are the relative convergence latencies for failovers and repairs?
Does bad news (withdraws) travel faster?
Bad News Does Not Travel Fast!
Impact of delayed convergence on E2E connectivity?
After a failover, how long before my site is reachable?
Avg. packet loss to 100 web sites (1 min bins in the ten mins
preceding and following a routing update)
Given best current routing practices, inter-domain BGP convergence times degrade exponentially with increase in the degree of interconnectivity for a given route
… and the degree of inter-connectivity (multi-homing, transit, etc) is increasing
healthcare, education, ...
Challenges Facing Today’s Internet are
Bandwidth and Latency
The Next Challenge Jeopardizing the Explosive
Growth of the Web is AVAILABILITY.