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

Bob Edwards bob at cs.anu.edu.au
Fri May 12 02:25:53 UTC 2017

Thanks for all the helpful homework, Seamus - I am definitely looking
forward to your presentation.

A heads-up for others that this talk is likely to be heavily networking
oriented and not specifically about anything Linuxy. The tools are all
open-source and the protocols all open, so worth celebrating from a
Linux/FOSS point of view.

As with all the CLUG talks, some "Linux Users" (LU in CLUG) will
likely get a lot out of this but others may find it not so relevant
or not targetted specifically at their level. YMMV, as they say.


Bob Edwards.

On 11/05/17 23:50, Seamus Murray via linux wrote:
> 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)"
> Links...
> https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol
> https://en.wikipedia.org/wiki/Traceroute
> https://en.wikipedia.org/wiki/Internet_Protocol
> https://en.wikipedia.org/wiki/Transmission_Control_Protocol
> https://en.wikipedia.org/wiki/Time_to_live
> https://en.wikipedia.org/wiki/Ping_(networking_utility)
> https://en.wikipedia.org/wiki/Van_Jacobson
> https://tools.ietf.org/html/rfc1918
> https://tools.ietf.org/html/rfc792
> Cheers
> 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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