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Gísli Hjálmtýsson – Reykjavík University
Architecture Challenges in Future Network NodesArchitecture Challenges in Future Network Nodes
Prof. Gísli HjálmtýssonNetwork Systems and Services Laboratory
Department of Computer ScienceReykjavík University, Reykjavík, Iceland
http://netlab.ru.is
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Overview
• Background and Motivation• Reality Check & Implications for Routers• A New Approach to Rapid Service Creation• A New Architecture for Network Nodes• Example Services• Summary
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Acknowledgements
• Björn Brynjúlfsson, Heimir Sverrisson, Ólafur R. Helgason @ Reykjavik University
• Bernhard Plattner, Kostas Katrinis @ ETH
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Active Networking Motivation
• Service deployment – rapid service creation– High margin for new services – competitive edge– Same drivers as for AIN in telephony
• Standardization takes too long– IETF's complexity is growing exponentially– So is time to standardize – Multicast, mobile IP, IPv6, etc. has taken forever
• Technology trends– Rapid growth in bandwidth and # of transistors (cycles)– Counting instructions in data-path is passé
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Proven that it can be done
• No technical show-stoppers• Time scale of programmability – NOT AN ISSUE
– Auto-deployment sufficient, timescales of minutes or hours
• Time scale of activity – Principle of timescale– Per packet timescale hard, 100 times that easy
• Model of programmability – Practical convergence• Interfaces – a number of viable alternatives
– Packet processors minimize this interface
• Program @ levels – services vs. extensible routers• Composability – Doable to some extent
– Feature interaction problem remains.
• Granularity – NOT a critical issue
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Did Active and Programmable Fail?• No, but it does not warrant a separate
discipline– AN ideas have gone mainstream
• Sensor networks, adaptive middleware, autonomic networks, overlays
• Significant impact on Router Architecture– All kinds of functions now appearing on routers– Modular routers, FORCES working group
• Some of the same ideas appearing in overlays
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Overview
• Motivation• Reality check & Implications for routers• A new approach to rapid service creation• A New Architecture for Network Nodes• Example Services• Summary
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Reality check – Impact
• No significant impact on router vendors– No significant router vendor offers an open
programmable interface
• No significant impact on the “Sigcomm” crowd– AN as a research agenda has died– AN has had some but limited direct impact on the
agenda of other researchers
• AN adds to the complexity of the Internet
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Reality check – Complexity
• Complexity is a real threat to the Internet• Configuration causes most Internet failures• … and dominates management cost
– AN has NOT help with routing, addressing, or protocols
• Need simplicity - must reduce the complexity– Self-configuration etc. is needed– Automation is not enough
• The pressing problem that need to be solved is reduction in (distributed) complexity
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Overlays have taken over
• Service deployment is focused on overlays and P2P– The new network service has become DHT
• Incremental deployment a critical issue– Application layer approaches inherently solve this
• Increasing push for a cycle/pipe model– Nodes not offering cycles seen as dumb forwarders
• PlanetLab the mother of all overlays• Application level overlays offer a very simple
programming interface– Inherent driver to maintain end-system model
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Problems with Overlays
• Introduce significant complexity – Cross-layer conflicts source of complexity– Prevent information exchange between layers.
• Fail to exploit capabilities of the underlying facilities – Specific hardware support and network processors– Increasing agility of the lower layers (tunable lasers)– On-demand allocation of optical light-paths.
• This is the architecture challenge in future networks– Finding the best (node) architecture for overlay based services
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Overview
• Motivation• Reality Check & Implications for Routers• A New Approach to Rapid Service Creation• A New Architecture for Network Nodes• Example Services• Summary
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Architecture goals
• To self-configure and self-optimize, fully exploiting the hardware facilities at each node and across a network of nodes, without explicit instructions from network programmers.
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Implications – Departure from AN• Operate with very limited service information• Move away from direct manipulation of facilities• Instead adapt to observed use and traffic
patterns• Autonomic properties – observe and adapt
– Self-configuring, self-optimizing, self-healing
• Cross-node coordination of services– Largely ignored in AN research
• Measurements become a first class functionality
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Measurement: first class function• Measure and monitor service level
topologies– Maintain consistent service quality– Monitor protocol behavior
• Require observations inside the network– Accuracy, detail, timeliness and responsiveness– Network tomography only computes long term averages
• Want generic mechanisms to provide– The right abstractions for service generic monitoring– Extensibility for service specific monitoring
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Distributed Service Level Control • Control plane across multiple nodes
– Common services need coordination between nodes
• Much od the overlay/P2P work has nice ideas– Want to exploit them at control level– Still continue to get the benefits of network layer
forwarding facilities
• Maintaining and adapting the topology • Programmability is not a research issue
– Easy to do – use with discretion where needed
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Overview
• Motivation• Reality Check & Implications for Routers• A New Approach to Rapid Service Creation• A New Architecture for Network Nodes
– The old model– The new model
• Example Services• Summary
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
The Pronto Router – A Node OS
Environment
manager
ActiveServices
Signaling Other CPU Sched
Classifier Packet Processors
Node OS
EE
Kernel
User
• Consistent with the DARPA Node OS framework• Service programming provided in EE• Router extensibility supported by packet processors
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Service programming with Pronto• Dynamic introduction into EE (user level)
– Program using C++, Perl, Java
• Programmed by service providers• Typed flows, rather than typed datagrams
– Still acts at connectivity level or at data level– May assign, and reassign policies at any time
• Principle of timescales• Push functionality to the highest layer/plane
viable for the timescale of a given task
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Extensibility of the Pronto router• Packet processors – A new kernel abstraction
– Provides programmability for hardware vendors
• Simple abstract interface– Type specific service interface (SAPI)
• Chains of packet processors make paths– Assigned to a filter in the classifier
• Paths can cross into user space• … or cross CPU boundaries (NP)• Examples:
– Forwarding, Tunnel entry/exit, IPSEC tunnels, NAT, TCP splicing, dropping, QoS, restoration, snooping
EM
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Service Description Layer
Facilities
Resources
A model refinement – New Node OS
Distributed Control Plane
Node OS
EE
Kernel
User
• AN has not observed the boundaries• Focus has been more lower level
HW, Network Pocessors, Optics
Abstract facilitiesIncl. measurem.
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Four layers of abstraction
• Service Description layer– Goal oriented description of the service requirements – e.g. delay, jitter, loss rate; more fuzzy “interactive media”
• Distributed Control Plane – Transforms the requirements to the available facilities – Coordinates across the nodes involved in the service delivery
• Facilities layer – Abstract interface to the forwarding engine’s functions – Examples: packet classification, forwarding and tunneling
• Resources layer – Special purpose resources for network functions on the node – E.g. tunable lasers, specialized hw, network processors
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Overview
• Background and Motivation• Reality Check & Implications for Routers• A New Approach to Rapid Service Creation• A New Architecture for Network Nodes• Example Services• Summary
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Examples
• Basic IP Services– Service description: TCP/UDP– Distributed control: Routing, Network wide measurement
collection and observation, load balancing, topology adaptation– Facilities: Classification, forwarding, local measurements,
tunneling– Resources: Topology adaptation (e.g. optical path allocation),
network processors, other special purpose hardware
• Peer-to-peer CDN– Service description: Interactive streaming audio/video, cashing
style CDN– Distributed control: DHT or other structure for locate/find, load
balancing, overlay topology management, measurements– Facilities: Forwarding, tunneling for topology adaptation, local
measurements– Resources: Low level topology adaptation
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Examples II
• Mobile support for streaming media– Service description: Whatever the base service is, e.g. interactive
audio and/or video– Distributed control: user/entity registry used for locate/find,
locate/find, user tracking – Facilities: 1-N classifier mappings, tunneling, local basic
measurements (same as for multicast)– Resources: Same as for basic IP services
• Enterprise level VPN– Service description: SLA– Distributed control: Basic IP, SLA conformance enforcement,
dedicated topology management (e.g. for performance, or privacy/security), VPN specific routing, Authentication etc.
– Facilities: Basic IP services, plus IPSEC– Resources: Same as basic IP services
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Autonomic Multicast
• Service description: – multipoint streaming - interactive or not, – delay/loss sensitivity
• Distributed control: – Gtrace – measurement and monitoring, – SLIM multicast protocol daemon, – Autonomic service adaptation
• Facilities: – 1-N classifier mappings, tunneling, local measurements
• Resources: – Same as for basic IP services
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Autonomic multicast service
• Have built network layer SSM (SLIM)– Self-configures over the unchanged Internet
• Monitoring protocol to collect distribution attributes– Combines a multicast/gathercast protocol– Collect basic properties of distribution trees
• Height, weight, losses, etc.
• Each node in the distribution tree participates– Rapid tracking of tree properties
• Every node in the tree knows subtree stats– Each node recursively can act like a root of a subtree
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Gtrace monitoring
• Local maintenance and collection– Collect information from local topology manager
• Information distribution– Propogates queries and information from a collection point to
nodes of the collection channel• Information gather
– Gather information from nodes of the topology the root• Can dynamically change the ÷ and + functions
+
Gather
Local Topology
State
Information from downstream nodes
Information toward root
Information to downstream nodes
Distribution
÷
Information from upstream node
Local Topology
State
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Effectiveness of the monitoring
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Autonomic adaptability
• Distribution tree recursively monitors performance
• Provides consistent service quality throughout the distribution tree, by– Activate local retransmissions (reduce observed losses)– Increase priority of the data-stream (reduce latency)
• Includes recovery/restoration (rapid rejoin)• Dynamic adaptation of the distribution tree
– From shortest reverse path to minimum cost spanning
• Example: TV station– Declares service level objectives (e.g. loss/delay)– Autonomically maintain consistent service quality
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Overview
• Background and Motivation• Reality Check & Implications for Routers• A New Approach to Rapid Service Creation• A New Architecture for Network Nodes• Example Services• Summary
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Summary
• Direct manipulation of network facilities by service programmers increases complexity
New paradigm – promote simplicity for services• Autonomically adapt to offered services
– Adapt topology and functionality to match needs
• Coarse grained service descriptions/objectives• Principle of timescales – match action and
urgency• Local operations – service wide coordination
Gísli Hjálmtýsson – Háskólinn í Reykjavík – [email protected]
Summary
• New architecture for network nodes • Four layers of abstraction
– Service Description layer – fuzzy service requirements – Distributed Control Plane – coordinates across nodes– Facilities layer – Abstract interface to facilities– Resources layer – Allows cross layer manipulation
• Goal to build the best node for overlay networks
• See: http://netlab.ru.is