[clug] Next CLUG meeting - May 25th 2017 - Traceroute and false diagnoses on networks

Seamus Murray clug at seamusmurray.com
Thu May 11 13:50:25 UTC 2017

Conventions and Terms Used in the Presentation...
The "traceroute" term is used as: 
- the name of the software tool, e.g. “use traceroute to test the connectivity from Host-W to Host-E” 
- the action of running the tool, e.g. “run a traceroute from Host-W to Host-E” 
- the results from running the tool, e.g. “look at the traceroute to help diagnose the issue” 

To keep things simple, I have only drawn a single IP address in the illustrations of the routers. In the real world, a router would have at least two IP addresses. 

The network addresses are written using CIDR notation (Classless Inter-Domain Routing), e.g.: 
- is the network range from to; 
- is the network range from to 

The term "node" refers to any devices capable of receiving or sending TCP traffic, such as compute host, router, firewall etc… 

The terms "route" and "path" are interchangeable. 

The terms "routing" and "forwarding" are similar, but vary slightly terms of magnitude:
- "forwarding" refers to sending a packet one hop towards a destination; 
- "routing" refers to sending a packet towards its destination (via one or more hops). 

The Term "ICMP Time Exceeded" is used in place of the full term "ICMP, Time-to-Live exceeded (Type 11), TTL equal 0 during transit (Code 0)"



Seamus Murray

      From: Bryan Kilgallin (iiNet) via linux <linux at lists.samba.org>
 To: linux at lists.samba.org 
 Sent: Tuesday, 9 May 2017, 23:26
 Subject: Re: [clug] Next CLUG meeting - May 25th 2017 - Traceroute and false diagnoses on networks
Thanks, Steven:

> * An animated explanation of how the packet loss and latency displayed
> in the output of traceroute can cause you to make a false diagnosis.

Seamus, I would like a reminder on the technical terms.

> * Series of diagrams and animations that illustrate each of the topics
> mentioned above.

I'd like a link to these posted here.

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