Network Cost Services for Network-Aware FI ApplicationsEC FIARCH WORKSHOPGEORGIOS GARDIKIS, GEORGE XILOURIS, NCSR “DEMOKRITOS”
Network Awareness
• Promising aspect within the FI scene• On-demand signaling of specific network-layer metrics
to querying applications aiming in optimization of application behavior and performance
• Within the generic “Resource Awareness” FI design principle.
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Current Status
• Present model: implicit derivation of network status (e.g. TCP)
• Applications assume network conditions by observing their own performance
• Implicit network awareness has survived during the years, and works well for most of the applications
• It is also scalable
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Current Status - trends• Gradual paradigm shift from host-centric to content-centric
communication• Existing implicit mechanisms may be not as efficient due to new
communication architectures, beyond the traditional client-server:– peer-to-peer– CDNs/Content-centric networks– in-network clouds etc.
• Content is distributed into the network, rather than concentrated in a single server -> simultaneous communication with tens, hundreds, or even thousands of peers.
• Assessing the communication with each of these peers at application level via the usual in-band methods would pose significant overhead in the network, besides requiring a considerable amount of time.
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A Network Cost Service• A scalable and efficient way to provide explicit Network Awareness• Offered by Network Operators (or third-parties)• “Network Cost” (NC) assessment for any given pair or group of
network endpoints. • NC could be instantly exploited at application level in order to
optimize operations such as in-network content placement, peer selection, prioritization and load balancing.
• A similar approach is promoted by the Application Layer Traffic Optimisation (ALTO) WG of the IETF
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Use cases• peer-to-peer file sharing and streaming - for optimizing p2p
communication via selection of “best peers” i.e. peers with lower NC
• one-to-one and one-to-many real-time audiovisual communication – for a priori optimizing stream format and rate according to NC
• distributed caching, Content-Delivery Networks (CDN) and Information Centric Networking (ICN) – for choosing optimal locations for caching content within the network
• in-network clouds – for efficient load balancing, traffic distribution and resource transfer to optimal locations, including Virtual Machine (VM) migration.
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Generic Architecture
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Generic Architecture• Network Cost Query: pair or group of endpoints’ addresses,
optionally application type (for application-aware networks)• Response: Network Cost vector
where ci(a,b), denotes a certain network metric between endpoints a and b (e.g. hop count, one-way delay, average
packet loss, jitter/delay variation etc.)• Can be transformed to a scalar value, taking into account the
sensitivity wi of the specific application against each of the aforementioned metrics.
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Proof-of-concept implementation• Customised SNMP agents on Linux-based routers• On-demand execution of active end-to-end measurements
according to the OWAMP protocol (RFC 4656)• Configuration of measurements and collection of results over SNMP• Network Cost provided to applications over SOAP/XML protocol• NC elements:
– Number of hops traversed– Average One-Way Delay (OWD)– Average packet loss– Average jitter– Percentage of duplicates
• Also tested on DiffServ-enabled configurations (Network Cost varies upon different DSCP values)
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Proof-of-concept implementation
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Proof-of-concept implementation• OpenSource implementation of the SAM framework is available at
http://medianetlab.gr/opensource
• Technical information available in the work:
G. Gardikis, K. Sarsembagieva, G. Xilouris, A. Kourtis, “An SNMP Agent for Active In-Network Measurements”, in Proc. ICUMT 2012, October 3-5, 2012, St. Petersburg,
Russia (to appear).
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Considerations
• Security and Network Operator Privacy; authentication of the querying entity, anti-(D)DoS protection etc.
• Inter-domain operation – “assembling” NCs across a chain of network domains
• Inclusion of the access network; separate assessment of the access link and combining results with edge/core network statistics so as to form end-to-end cost in a scalable manner
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