Blind Men

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Information about Blind Men

Published on November 26, 2007

Author: Garrick


Blind Men Feeling the Elephant:  Blind Men Feeling the Elephant Managing Application Network Performance: Standards, Tools and Challenges Jill Gemmill, UAB Remember the “World Wide Wait”?:  Remember the “World Wide Wait”? Frustration with Internet congestion led to several initiatives NSF very Broadband Network Services (vBNS) Internet2 (University Corporation for Advanced Internet Development) Federal Next Generation Internet (NGI) and President’s Information Technology Advisory Committee (PITAC) Problems Causing Internet Congestion:  Problems Causing Internet Congestion No prioritization Non-geographic peering Limited Bandwidth (typically T1=1.5Mb/sec) No quality of service or service guarantees other than “delivery, eventually”. Internet2 Architecture :  Internet2 Architecture ATM? For wide area, then not at all. Now IP over SONET (OC48) and Gigabit Ethernet using switches Resulting in – (TCP) Performance via a private network of “Fat Pipes” (from 1.5Mb/sec to 655Mb/sec) Where’s the Beef? (PITAC vision of 100Mb/s to desktops):  Where’s the Beef? (PITAC vision of 100Mb/s to desktops) I2 performance better by factor of 2 ! Test at Pittsburgh Supercomputer Center, May 2000 with ATM to the desktop found: 50% of connections obtained 8 Mb/sec or less Only one host found that could attain sustained 80Mb/sec throughput No one knew why. Let’s Think About Network Traffic a Bit….:  Let’s Think About Network Traffic a Bit…. Application is broken down into packets Each packet is sent across the network and receipt is acknowledged Measures of network utilization look at how well packets are traversing the network OR % bandwidth filled by packets But…how is the application performing? What is the end-user experience? End-to-End Performance : Fat Pipes are Not Enough:  End-to-End Performance : Fat Pipes are Not Enough Key issues are: What is the application’s performance? (ie look up out of the TCP Transport Layer) How can you tell what needs to be fixed? Should the network be aware of application requirements? Should the application be aware of network conditions? Service Level Agreements:  Service Level Agreements Poor application performance costs money (lost transactions) Customers want SLA’s based on terms measuring application performance, not network utilization Applications cross multiple ISP’s (a single contract is not sufficient) End-to-End is a hard problem.:  End-to-End is a hard problem. It’s not just the network … Computer hardware design & speeds Does NIC match DMA? Enough memory? Operating System issues Has TCP stack been tuned to fully utilize bandwidth? Server Load Balancing working? Security Impact (firewalls, VPN..) Traffic Engineering Projects in IETF Transport WG’s:  Traffic Engineering Projects in IETF Transport WG’s IntServ (Integrated Services) RSVP (Reservation Setup Protocol) DiffServ (per flow state & signaling) MPLS (MultiProtocol Label Switching) IPPM (IP Performance Metrics) RTFM (Flow Measurement) ECM (Endpoint Congestion Mgt.) An Internet Measurement Architecture?:  An Internet Measurement Architecture? Standardized Measurements Standardized Measurement Architecture Useful to ISP’s and to End Users Its existence should not cause congestion Of course, User-Friendly How to Measure? :  How to Measure? Passive Packets? Flows? Save & Store Everything? Active What size? How often? Save & Store Everything? Device Status Routers, switches, hubs, end devices Which should you look at? Measurement Standards:  Measurement Standards IETF IP Performance Measurement WG (IPPM) founded 1998 Vern Paxson XWIT (Cross Industry Working Team) IPPM defines metrics; shares tools and procedures. XWIT plans to build tools based on these standards. Industry Practice Standards:  Industry Practice Standards Automotive Industry Action Group (VPN; 50,000 members; Bellcore) based on industry needs XWIT Cross Industry Working Team (NSF convened). Defining delay, etc. Distributed Management Team (Sun, MS, Novell, IBM…) Common Information Mgt. Model (CIM) object oriented Standards for Network Measurements:  Standards for Network Measurements ITU-T I.380 IP Packet Transfer & Availability T1A1.2 Network Survivability T1A1.3 Performance of Digital Networks & Services E.600 Vocabulary for traffic engineering E.701 Reference Connections for traffic engineering E.801 Framework for service quality agreement Standards for Network Measurements:  Standards for Network Measurements IETF RFC 2063 Traffic Flow Measurement Architecture ULM “Universal Logger Message” Draft; translated by syslog-sec working group to XML & developing API RFC’s for Secure Network Management Protocol (SNMP) & Management Information Base (MIB) RMON Empirical Bulk Transfer Capacity Metrics Draft What is a “useful” measure?:  What is a “useful” measure? Very highly defined & detailed, or imprecise but with reference to trends? Round-trip times One way packet loss DNS performance Network Resource Utilization Session Flow Analysis Bottleneck Link Bandwidth Jitter Application Time Server Time TraceRoute Bulk Transfer Capacity Bandwidth Utilization Time to Completion Clock skew/drift Wire Time Network Time Network Measurement Architectures:  Network Measurement Architectures XWIT Server-Based Measurement Infrastructure (for members) Surveyor (IPPM) one-way delay & packet loss AMP (NLANR MOAT) ping(RTT) and traceroute with web interface to results National Internet Measurement Infrastructure (NIMI) (NSF & DARPA) CoralReef (CAIDA) Internet End-to-End Performance Monitoring (DOE/SLAC) Internet2 E2E initiative Network Measurement @ UAB :  Network Measurement @ UAB 95+ buildings, 20,000+ users, I1 & I2 Bandwidth Utilization Device up/down status monitoring Participate in AMP Per-flow monitoring (passive) Scheduled simulations (active) Some “slow” applications or “natural candidates” for improvement Your Suggestions?:  Your Suggestions?

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