Routing as a Service

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Routing as a Service

• Karthik Lakshminarayanan
• (with Ion Stoica and Scott Shenker)
• Sahara/i3 retreat, January 2004

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Problem

• Applications demand greater flexibility in route
  selection
• Resilience RON, Tapestry
• Performance Detour
• Applications need different routing functionality
• Multicast ESM, Overcast
• DDoS defense SOS, Mayday
• Anycast Gia
• Difficult to change any routing-level component
  in the Internet today!

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Current approach

• Overlay networks
• Layer above IP
• Deployability
• Problems
• Ossification overlay solutions again ossify
  routing in the protocol hard to modify once
  deployed on large scale (lessons from the
  Internet)
• Efficiency replicate packets multiple times
  along a physical link inefficient route
  construction
• Lack of control for ISPs traffic hard for ISPs
  to control circumvent ISPs policies

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Routing in transportation network
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Our thesis

• Push routing out of infrastructure
• Argument for edge-controlled routing
• Related NIRA (NewArch group, MIT/ISI)
• Our contribution
• Fine-grained control over routing
• Control plane for achieving this

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System architecture

• Forwarding infrastructure
• Provides basic routing (referred to as default
  routing)
• Exports primitives for inserting routes

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System architecture

• 2. NEWS/Route selector
• Aggregates network information
• Selects routes on behalf of applications

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System architecture

• 3. End-hosts
• Queries NEWS to setup paths

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Architectural position
Infrastructure
Host
Data plane
Internet Infrastructure overlays
Control plane
P2P End-host overlays
Data plane
Control plane
Our proposal
Data plane
Control plane

• Separate control plane and data plane by using
  clean abstractions

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Challenges

• Open, multi-provider system (design of
  primitives)
• Unlike intra-domain, e.g. GSMP
• Security control provided should not be used for
  attacking the system
• Trust between entities of the system, e.g. what
  information does system give to NEWS
• Large-scale system (route selection)
• Scalability monitoring service to end-hosts
• Stability should not lead to oscillations
• Deployability ISP control

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Infrastructure primitives

• Label-switching-like primitive
• Allows insertion of forwarding entries (id1,
  id2), where id1, id2 are labels
• id NodeID LocalID
• Establishing paths Loose virtual path (LVP)
• Composition of label switches T (id1, id2, ,
  idn) is composed as (id1, id2), , (idn-1, idn)
• Construct different topologies
• Aggregation can be performed at the level of
  tunnels that end at infrastructure nodes

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1. Trust

• Infrastructure provides network information to
  NEWS

• Verification NEWS should be able to verify this
• Indirect measurement techniques using primitive
  alone
• Metrics Delay, loss, bandwidth

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1. Trust

• NEWS provides routes across the network

• Verification Network verifies correctness

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2. Scalability

• Monitoring
• Monitor a subset of links
• Update period depends on stability (exploit link
  stationarity)
• For e.g., updates can be sent when metric on the
  link changes by a factor of x
• Computation
• Incremental computation of best paths
• Multiple paths are returned
• Querying
• Default paths are used if special routing is not
  needed
• Hierarchical dissemination
• Caching of results TTL chosen to reflect
  stability of paths

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3. Deployment

• Infrastructure nodes
• Hosted at certain points within ISPs
• NEWS/Route selection
• 3rd party provider like Akamai
• Few in number
• Determined by application requirements
• Trust relations
• NEWS trusts infrastructure for information
  (verifiable)
• ISPs trust paths that NEWS returns (verifiable)
• Export links that obey the underlying policy
  constraints

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Implementation status

• i3 primitives for setting up forwarding state
• Distributed NEWS implemented
• Route computation based on delay, loss and
  bandwidth
• Deployed on PlanetLab
• i3 proxy has been modified to query NEWS
• Legacy applications can be used with NEWS

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Summary of results

• Verification of measurement techniques
• Delay 97 of cases have error lt 10
• Loss-rate 90 in over 80 of the cases
• Bandwidth Within a factor of 1.5 in 60 of cases
• Scalability of monitoring
• Simulation-based
• Logarithmic-degree graph
• Achieve 90 RDP of 2.3 (for delay) for TS-16384

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Summary

• Routing control pushed outside the infrastructure
• Routes computed by third-party entities (NEWS)
  along with measurement information provided by
  the infrastructure
• Leads to evolvable networks
• Deploy new routing schemes or optimize existing
  routing without changing the infrastructure