[clug] Um... Is there CLUG tonight?
Seamus
clug at seamusmurray.com
Sun May 28 09:26:11 UTC 2017
Here are the sample traceroute outputs that I presented.
Idealistic traceroute (for reference)
10 ms
20 ms
30 ms
40 ms
50 ms
60 ms
70 ms
80 ms
90 ms
Latency that the only present for some of the intermediary routers. Multiple potential causes, including..
Router control plane delays
1 or more long/slow return paths from 1 or more intermediary routers
10 ms
20 ms
30 ms
200 ms
210 ms
220 ms
230 ms
240 ms
90 ms
Packet loss that the only present for some of the intermediary routers. Multiple potential causes, including..
Router control plane no generating the ICMP Time exceeded messages
1 or more return paths from 1 or more intermediary routers causing packet loss
10 ms
20 ms
30 ms
*
*
*
*
80 ms
90 ms
In-line latency that continues all the way to the remote destination host
10 ms
20 ms
30 ms
200 ms
210 ms
220 ms
230 ms
240 ms
250 ms
MPLS ( I'll leave this for those who are interested to investigate them selves )
10 ms
20 ms
30 ms
90 ms
90 ms
90 ms
90 ms
90 ms
90 ms
Multiple potential causes, including..
Firewall on the remote destination host
Your local firewall/NAT dropping the returned traffic
10 ms
20 ms
30 ms
*
*
*
*
*
*
CheersSeamus Murray From: Bob Edwards via linux <linux at lists.samba.org>
To: linux at lists.samba.org
Sent: Friday, 26 May 2017, 9:59
Subject: Re: [clug] Um... Is there CLUG tonight?
On 26/05/17 07:28, Mike Carden via linux wrote:
> On Fri, May 26, 2017 at 6:29 AM, George at Clug via linux <
> linux at lists.samba.org> wrote:
>
>> Well I missed another meeting.
>>
>> The days, weeks and months are travelling way too fast for me.
>>
>> Was it a good night, what was discussed ?
>>
>
> The bit I saw before I had to go and be a taxi was very good. Seamus was
> digging into traceroute and what it does and doesn't tell you about what an
> IP network is doing.
>
> I hope that the resources from his talk are online somewhere because I
> really wish I hadn't missed the rest.
>
+1 - Seamus did a great job and his animated diagrams of how traceroute
output can represent many different scenarios were excellent.
Alas, his "slides" (9000 images, apparently, and around 8GB) are not
yet ready to be put on the web.
A huge thanks to him for travelling all the way from Sydney just to
present this talk for us.
One interesting point, early on in his presentation, was around 7
very different traceroute outputs for the same (hypothetical)
destination that were all good and one that may have been good or
bad - this brought home his point quite well, I thought.
He mentioned to me, after dinner, that DigitalOcean and Linode both
have tutorials on traceroute that are worth a read, although the one
I found on DigitalOcean seemed to be making some opposite (and naive)
points to Seamus's talk. For example, Seamus talked down the use of
mtr (My TraceRoute), but the DigitalOcean tutorial talks it up, etc.
cheers,
Bob Edwards.
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