Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Quality of Service for Remote Control in the High Energy Physics Experiments: a Case Study Tiziana Ferrari INFN - CNAF

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Overview Quality of Service differentiated services architecture application characterization service definition and implementation future work

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Quality of Service: problem statement today: single service, best-effort Service: type of “data” treatment during transmission across the network -qualitative -quantitative (delay, instantaneous delay variation, packet loss, throughput, MTU, congestion treatment) Class: set of packets to which a given service applies Benefits: -congestion management -differentiated allocation of expensive network resources (ISP) -application: differentiated treatment of streams according to their requirements and priority -guarantees of congestion independent parameters (e.g. delay variation)

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Differentiated services Why the differentiated services (diffserv)? -independent of layer 2 technologies -interoperability between independent national research networks (different requirements, infrastructures, policies and management) -traffic aggregation -scalability -no signalling -QoS for networks not ATM based

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Diffserv architecture components DS field (1 byte) - IP header - packet classification packet scheduling traffic conditioning: -metering -marking -policing -shaping DS field CU 067

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Diffserv architecture: PHBs Per Hop Behaviours: description of the packet treatment into the network Standardised PHBs: -Expedited Forwarding (low delay, low delay variation, guaranteed bandwidth) -Assured Forwarding (Behaviour Aggregate, 4 classes, 3 drop priorities per class) Experimental PHBs PHB class selectors: XXX000 (backward compatibility with TOS precedence)

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Diffserv architecture: network model DS domain Non-DS capable domain MPLS Core domain marking Marking policing scheduling shaping DS domain ATM DS region

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Application characterization Goal: identification of the application requirements for service definition 1Trigger hardware remote control 2Monitoring: quality and correctness of analysis results

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Application 1: trigger hardware remote control VME Server 1... Client 1 Client 2 Client 3 Client n... bottlenecks VME Server 2 Server m R1R2R3 ROBIN client - server, duplex exchange of data, interactive few transactions (low bandwidth) TCP ports and IP address of the server known one-way delay sensitiveness high reliability (packet loss probability, bandwidth) burst tolerance

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Application 2: Analysis monitoring server... bottleneck exchange of analysis results (root object) duplex, asymmetric traffic volume low bandwidth consumption client - server, TCP, IP address of server and clients known packet loss tolerant minimum bandwidth guarantee per client dynamic allocation of the maximum overall capacity allocated

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Service Level Specification (SLS) - 1 Hardware remote control: -packet classification and marking (at the edge): if (pack(src) = (s 1 || s 2 || … || s m ) && pack(dst) = (d 1 || d 2 || … || d n ) && protocol = TCP && pack(port)  [x, y] ) then label(pack) = max precedence -bandwidth guarantee (through policing): max service rate = 64 Kbps * N src 64 kbps : estimated rate consumed by 1 server/client N src : number of servers (upstream) of clients (downstream) if (traffic <= max && burst <= 64 kby) then label = Expedited Forwarding else label = best-effort -one-way delay (through scheduling): priority queuing

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Service Level - 1: implementation scheduling VME Server 1 VME Server 2 VME... Client 1 Client 2 Client 3 Client 4 r R Server 8 marking R R r r traffic, max rate R schedulingmarking Server  client: traffic, max rate r policing PQ Client  server:

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Service Level Specification -2 Analysis monitoring: -server  client: *packet classification and marking (at the edge): if (pack(src) = s && pack(dst)=(d 1 || d 2 || … || d n ) && protocol = TCP) then label(pack) = PHB  Assured Forwarding(AF)class *bandwidth guarantee (through policing): max service rate per client = 256 Mbps min rate per client: 64 kbps for each client: if (traffic <= min && burst <= 16 Kby) then label = AF11; else if (traffic <= max) then label = AF12; else drop(packet) *scheduling: Weighted Fair Queuing *traffic differentiation: Weighted Random Early Discard

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Service Level Specification -2 (cont) -Client  server: *packet classification and marking (at the edge): if (pack(src) = d i && pack(dst) = s && protocol = TCP) then label(pack) = PHB  Assured Forwarding(AF)class *bandwidth guarantee (through policing): max service rate = 5 Mbps min rate per client: 64 kbps for each client: if (traffic <= min && burst <= 16 Kby) then label = AF11; else  label = AF12; if (traffic(Af12) <= max) then OK else drop(packet);  *scheduling: Weighted Fair Queuing *traffic differentiation: Weighted Random Early Discard

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Service Level -2: implementation scheduling Server Client 1 Client 2 Client 3 Client 4 r marking R r r r traffic, max rate R schedulingmarking Server  client: traffic, max rate r policing WFQ Client  server:

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Scheduling: PQ vs WFQ Priority Queuing: absolute precedence over any other queue one-way delay minimization WFQ: distribution of bandwidth between queues according to the weight associated to each of them

Tiziana FerrariQuality of Service for Remote Control in the High Energy Physics Experiments CHEP, 07 Feb Future work Fermilab ESnet diffserv Testbed European diffserv testbed or ATM p-2-p link Test site 1... Testbed configuration tuning of router configuration validation of the EF : priority queuing, burstiness and scheduling validation of the AF implementation: WRED configuration