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ECE498 Introduction to Network Engineering

ECE498 Introduction to Network Engineering. Professor Bruce Segee Fall 2000. What is Network Engineering?. Net-eng is the profession of designing, upgrading, and implementing network systems.

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ECE498 Introduction to Network Engineering

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  1. ECE498Introduction to Network Engineering Professor Bruce Segee Fall 2000

  2. What is Network Engineering? • Net-eng is the profession of designing, upgrading, and implementing network systems. • Net-eng is not exclusive to the data network field; telecommunication engineering (telcom-eng) is very similar to net-eng.

  3. Why is Net-Eng Important? • Today’s Internet infrastructure would be non-existent without network engineers. • Existing infrastructure would fall into ruin over time- optimization and repair would not occur.

  4. What is a Network? • A network is any system of interconnected devices which communicate over a shared medium. • The medium can be almost anything- a physical cable, or a wireless link. • A single network can consist of multiple, smaller networks.

  5. What Is the Internet, then? • Well, quite honestly, it’s a big convoluted mess. • The Internet consists of thousands of smaller, (not necessarily compatible) networks. • The links between networks can be physical (telephone line), wireless (cell phone), satellite, etc.

  6. The Mess

  7. Internet Growth

  8. Why is the Internet Growing?

  9. Common Network Problems • Latency • Packet loss • Routing problems • Too many “hops” • Lack of peering (public or private)

  10. How Do We Fix The Problem (Instead of Patching It?) • Upgrade. Increase the capacity of the network interconnects. • Consolidate. Migrating equipment and services to a centralized location improves network efficiency, and decreases “hops.” • Decommission. Removing legacy equipment and closing locations reduces required manpower and maintenance.

  11. How Do You Know When to Fix Something? • Two main factors are involved in the decision: • Does it affect customers/end-users in any way? • How much does it cost? • Unfortunately, when talking about long-term goals, it usually comes down to money.

  12. Something’s Broken! • If you find that something is broken,you have quite a few tools at your disposal to determine what the problem is: • “Ping” • “Traceroute” • Network/protocol analyzers

  13. Ping • Ping is the most common way of determining if a host is “alive.” C:\WINDOWS\Desktop>ping 199.1.11.2 Pinging 199.1.11.2 with 32 bytes of data: • A couple things can happen at this point…

  14. Ping (cont.) • Routing is wrong: Destination host unreachable. Destination host unreachable. Destination host unreachable. Destination host unreachable. Ping statistics for 199.1.11.2: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms

  15. Ping (cont.) • The host may be unresponsive: Request timed out. Request timed out. Request timed out. Request timed out. Ping statistics for 199.1.11.2: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms

  16. Ping (cont.) • Or it may be up and responding to network requests: Reply from 199.1.11.2: bytes=32 time=181ms TTL=248 Reply from 199.1.11.2: bytes=32 time=185ms TTL=248 Reply from 199.1.11.2: bytes=32 time=185ms TTL=248 Reply from 199.1.11.2: bytes=32 time=660ms TTL=248 Ping statistics for 199.1.11.2: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 181ms, Maximum = 660ms, Average = 302ms

  17. Ping (cont.) • The important aspect of ping is that the program shows if the host is responding to network requests. • Minimum, Maximum, and Average round-trip times are reported. Good for diagnosing latency issues.

  18. Traceroute • Traceroute is one of the other staple tools of a network engineer. • Traceroute allows someone to determine where a slowdown (congestion) occurs between his machine and a target host. • Windows command: tracert • UNIX command: traceroute

  19. Traceroute (cont.) C:\WINDOWS\Desktop>tracert 199.1.11.2 Tracing route to ns.onramp.net [199.1.11.2] over a maximum of 30 hops: 1 111 ms 106 ms 105 ms srv6-2-16.ipls.bd.ans.net [207.205.227.128] 2 105 ms 105 ms 110 ms core-ipls1-fe0/0/0.grid.net [207.205.227.252] 3 140 ms 145 ms 135 ms core-wash1-atm4/0.9.grid.net [206.80.190.90] 4 149 ms 150 ms 140 ms f0.iad1.verio.net [192.41.177.196] 5 145 ms 145 ms 150 ms p1-1-0-0.r03.mclnva01.us.bb.verio.net [129.250.2.182] 6 190 ms 185 ms 190 ms p1-0-2.r00.dllstx01.us.bb.verio.net [129.250.2.209] 7 190 ms 190 ms 190 ms ge-1-0-0.a10.dllstx01.us.ra.verio.net [129.250.31.58] 8 190 ms 185 ms 190 ms fa-8-0-0.a09.dllstx01.us.ra.verio.net [129.250.28.170] 9 185 ms 190 ms 185 ms tun6501601.r00.dllstx01.us.to.verio.net [157.238.225.206] 10 190 ms 190 ms 190 ms ns.onramp.net [199.1.11.2] Trace complete.

  20. Internettrafficreport.com • This site provides a general idea about how Internet traffic flows. Higher numbers are better.

  21. Some More Graphs

  22. What Does All of This Mean? • The Internet is a dynamic, routing nightmare where Murphy’s Law is always in effect. • The ability to diagnose a problem is half the problem; Getting the right person to fix the problem is the other half.

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