Profile

Cover photo
Phil Benchoff (N3PB)
Works at Virginia Tech
Lives in Blacksburg, VA
127 followers|48,570 views
AboutPostsPhotosVideos

Stream

Phil Benchoff (N3PB)
owner

Other Images  - 
 
Small fixup of recent Dilbert.
10
2
TJ Evans's profile photoMartin Seitl's profile photo
Add a comment...

Phil Benchoff (N3PB)
owner

Other Images  - 
 
Here is a slide from "IPv6 in the DREN III acquisition" by Ron Broersma, 10 Jun 2014.  "Our #1 rule: if we can't get to the company or product website via IPv6, we won't consider such products."
12
1
Dan York's profile photoWesley George's profile photo
 
Awesome slide... I'll note that the full slide deck is available here:

https://spaces.internet2.edu/download/attachments/40108073/IPv6-DREN-III-Acquisition-RonBroersma.pdf
Add a comment...

Phil Benchoff (N3PB)

Shared publicly  - 
 
This showed up on Twitter today.  I thought, "Certificate authorities are kind of messed up, but this might be a bit excessive."  Oh, right, there's a state abbreviated CA too.
3
Wesley George's profile photoDan York's profile photo
2 comments
 
Good one!
Add a comment...

Phil Benchoff (N3PB)

Shared publicly  - 
 
Since it's throwback Thursday....
$user says he cannot download a particular file.  Sure enough, the download stops at the same place every time we try.  I download the file to a host outside our network with no problem but it stops at the same point downloading from that host to our network.  Slice and dice the file with dd and we get a 1k portion that will not download.  A quick look with xxd shows a block of \xb5 characters.  Sure enough, we cannot download a file of more than 70 bytes of \xb5.  (Oddly enough, x5b is no problem.)  +Eric Brown figures out that there is a framing error for every one of those packets on one of our links.  The same data coming in any other link is fine.
The only reason I had to believe that something like this is even possible is that I have seen it before.  Twenty or so years ago, we had a packet that would not cross our FDDI ring in one direction.  After a week or so of hair pulling, we figured out that a packet could not be received by one of our routers.  Cleaning the fiber optic connector fixed it.  (Cisco AGS+.  Chip was suspected to loose timing on certain bit patterns and dirty connector pushed it over the edge.)
We don't know exactly what's going on with the circuit in question, but I would never believe a small packet just won't go if I had not seen it before.  For once, ancient knowledge put us ahead in the diagnosis of a problem.

ping -p b5 -s 88  -c 100 x.y.z.net
[...]
--- x.y.z.net ping statistics ---
100 packets transmitted, 55 received, 45% packet loss, time 99068ms
rtt min/avg/max/mdev = 35.554/36.533/38.681/0.733 ms

$ ping -p 5b -s 88  -c 100 x.y.z.net
[...]
--- x.y.z.net ping statistics ---
100 packets transmitted, 100 received, 0% packet loss, time 99139ms
rtt min/avg/max/mdev = 35.571/36.476/39.362/0.768 ms
3
Add a comment...

Phil Benchoff (N3PB)
owner

Other Images  - 
 
IPv6: It's Not New.  It's Now.  (downloadable images from ARIN)
1
1
Iestyn Best's profile photo
Add a comment...

Phil Benchoff (N3PB)

Shared publicly  - 
 
I was asking someone at NIST about IPv6 on their public time servers and found out that they are considering restructuring their public time servers.  The comment period ends 18 March.

From the linked document:
National Institute of Standards and Technology (NIST), Department of Commerce, seeks information from the public on NIST's potential transition of time services from a NIST-only service to private sector operation of an ensemble of time servers that will provide NIST-traceable time information in a number of different formats over the public Internet.
SUMMARY: National Institute of Standards and Technology (NIST), Department of Commerce, seeks information from the public on NIST's potential transition of time services from a NIST-only service to private sector operation of an ensemble of time servers that will provide NIST-traceable time ...
1
Add a comment...

Phil Benchoff (N3PB)
owner

Legacy IP Only Stickers  - 
 
FOSDEM 2014 had a NAT64 network.  The link below is to a presentation on that network and IPv6 in general.  A Legacy IP sticker makes an appearance on one of the slides.
2
Add a comment...
Have him in circles
127 people
Phil Fenstermacher's profile photo
Emily James's profile photo
Bruce Snelgrove's profile photo
Bill Owens's profile photo
Joe Hutson's profile photo
karen Everhardt's profile photo
Jim Jordan's profile photo
steve wells's profile photo
Richard Shumaker's profile photo

Phil Benchoff (N3PB)

Shared publicly  - 
 
A little IPv6 from +Lifehacker.
Support for IPv6 is enabled by default in most operating systems, and legend has it that disabling it will increase your internet speed. That's not really true, and here's why.
1
Add a comment...

Phil Benchoff (N3PB)

Shared publicly  - 
 
This comes from a building renovation on campus.  Only one of my coworkers could identify it.  Most of them laughed when I explained what it was.
3
Ron Jarrell's profile photoThomas Weeks's profile photoPhil Benchoff (N3PB)'s profile photo
12 comments
 
+Thomas Weeks   The core memory photo.
Add a comment...

Phil Benchoff (N3PB)

Shared publicly  - 
 
This article http://www.ijs.si/time/temp-compensation/ says that temperature has a significant effect on the stability of a computer clock oscillator.  Here is a plot of ambient temperature versus frequency offset for a Beaglebone Black running NTP.  The board was not in a case.  I have put it into a cardboard box to see what happens, but it's pretty clear some temperature compensation would help.  This server does not have a local reference clock, so the time isn't all that good anyway.
2
Leo Bicknell's profile photoRichard Godbee's profile photoClark Gaylord's profile photo
3 comments
 
Periods look similar. Do you have an estimate of phase offset?
Add a comment...

Phil Benchoff (N3PB)

Shared publicly  - 
 
In the late 1980s Virginia Tech and Bell Atlantic did a project to offer data connectivity over POTS lines. So far as I know, I'm the second person in the US to have a data-over-voice connection on a residential phone line (very much like today's DSL, but at a lower speed). This was right after divestiture and the RBOCs were trying to create a integrated voice and data service that could compete with owning your own PBX.
C.O.LAN Bell Atlantic's post-divestiture entry into the integrated voice and data market. Coherent voice-over-data modems on POTS lines with a Datakit VCS in the CO. 19.2kbps async data over voice in the days of 2400bps modems. Virginia Tech was the first place in the country to have a residential connection. Late 1980s.
3
1
Scott Fenstermacher's profile photo
Add a comment...
People
Have him in circles
127 people
Phil Fenstermacher's profile photo
Emily James's profile photo
Bruce Snelgrove's profile photo
Bill Owens's profile photo
Joe Hutson's profile photo
karen Everhardt's profile photo
Jim Jordan's profile photo
steve wells's profile photo
Richard Shumaker's profile photo
Work
Occupation
Network Engineer
Employment
  • Virginia Tech
    Network Engineer, 1983 - present
Basic Information
Gender
Male
Other names
N3PB
Story
Bragging rights
Network engineer at an institution that has one of the oldest and largest native IPv6 deployments anywhere. I remember when our Proteon router crashed when the global (legacy IP) routing table exceeded 400-some routes. Amateur radio callsign N3PB.
Places
Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Currently
Blacksburg, VA
Previously
Hagerstown, MD