A network benchmark update

Previously, I've posted several Comcast / Xfinity's benchmarks for our CATV Internet service.  (Click on "Benchmark" topic at right.)

Lately, the IPv6 service seems pretty reliable with my system.  That was a problem for some time.  It may have been a bad interaction between the Comcast plant and my local routers, but it just went away.  It may have been a Comcast reconfiguration that helped us, but it also could have been an Asus firmware update. I am now running ASUSWRT-MERLIN firmware on the Asus RT-N66U router, which I can highly recommend as an expanded and improved version of the Asus distribution.(It cured a long-standing issue with JFFS2 overflow.)

Again, I highlight the DSL Reports speed test, which checks your "real world" network performance, including the dread "buffer bloat".  Today is Boxing Day (Dec. 26), and DSL-Reports is giving me a so-so report and a good report. Here they are, separated by half an hour:

The variability may be partly due to the speed test's different selection of test hosts.  But it may be something real about Comcast or the Internet "weather".  These tests use IPv6, it appears.

For comparison, between these two tests, Comcast's own speed test shows this:

This is the available speed within the Comcast network, which seems to be the best possible result -- not fully representative of what you experience with a random Internet connection -- even if the server is fast and well-connected. (Note that the driving distance from Branford CT to Boston is really about 144 miles, not under 50. Go figure.)

Prefixes I have known (WPX)

Recently received some more wallpaper, attesting to the number of "prefixes" I have contacted on the Amateur bands over 50+ years -- 550 Digital and 600 total.  (There are a lot of prefixes out there.  AA6 is different from AA7, etc.)  Digital contacts include RTTY (radio teletype), PSK31 (phase shift keying), and (mostly) JT65/JT9.

Latest project

What is it?

Windows 10 "Anniversary Update" & Ham Radio

There are 3 Windows 10 systems in the house.  I chose the least important one (a Toshiba laptop) to be the first sacrifice for the latest Microsoft update.  These updates are big deals.  This one took nearly 2 hours start to finish, and it had me go through the new installation checklist to decide what data gets shared with Redmond.  (I generally minimize that, hoping to keep a smidgen of privacy.)

The good news, apart from the long waiting for things to complete, is that my laptop is back to what it was before. Supposedly, there are benefits in the user interface -- more Cortana, etc., but they can be ignored fir the time being.

The truly worrying part of Windows evolution is that MS is asserting ownership of my data and my computing life in more and more ways.  In the name of "convergence", my PC is morphing into a cell phone, and I find myself slipping into the MS walled garden.  Why, it's enough to keep me on Linux for most of my work!

Unfortunately, I do need to keep Windows around for my Amateur Radio operations -- running the Flex 6500.  That is my "big" computer.  It will be the last one to be updated, given that the Flex software may need special TLC when there's a major Windows update.

IPv6: Things that fix themselves

In a January post, I commented on trying to make the new Internet Protocol (IPv6) work in my household.

Despite some detailed sleuthing, I could not get IPv6 working reliably on my WiFi/Ethernet local area network with its connection to our ISP, Comcast.  The router would give up after a day or so, reporting ICMP6 checksum errors and shutting down IPv6 service.  (IPv4 worked well, regardless.)

I had tried swapping out a lot of my devices, including routers, but nothing seemed to keep the service going for more than 24 hours.  Lacking more elaborate packet inspection tools, I put the whole thing on the shelf.

Now, after 5 months of computer / Internet life, I thought I'd check in again.  What do you know -- IPv6 is stable now.  There have been quite a few updates to operating systems, routers, and other components since January, so it's not possible to say what made the difference.  And Comcast may have secretly changed its service in a way that cured my bug.  (The log still reports bursts of ICMP6 checksum errors, by the way.)

We may never know what happened, and that's a shame because it is good to know where the weak links are (or were) to help plan future developments.

Meanwhile, laissez les bon temps rouler!  We are ready for the next century.

p.s. This is mainly a hobby activity.  There is practically nothing you can do with IPv6 that you can't do with the common IPv4.  (You can test your own IPv6 capability here.) Over time, since the IPv4 system is now almost out of available new addresses, new services will have to be provided on IPv6 only.  But that may be a while yet.

Modest Ham Radio Milestone (LoTW)

Personal Best Dept:

My Logbook of the World (LoTW) account just turned 2,000.  That's the number of confirmed "electronic QSLs".  My digital log stretches back to the 1980's at least. (I wish I still had my earliest logs, starting in 1958 or so!)

This will not set the world of amateur radio on fire.  Many folks are a lot more active than I am.  With a little grit, you can get 2,000 contacts in a single weekend contest!  But it's meaningful to me, in a Sunday-driver kind of way.

Another interesting statistic is that my percentage confirmed on LoTW is just about 50% now, a big improvement over the last few years.  Largely, that is due to a lot of JT65 / JT9 contacts, where LoTW confirmations are very common.  (The folks who are able to set up for digital modes are also likely to be able to handle the still-somewhat-arcane LoTW procedures.)

I still like to send and receive the traditional paper QSL cards, but I confess I have not solved the problem of how to store and/or display them.

IPv6: Light my Fire!

Our IPv6 story continues.  We removed our Asus RT-N66U router and showed that the problem (long periods of dropped IPv6 connectivity) was not in the Asus device.   The problem continued when we went back to the Comcast/Cisco DPC 3941T router, alone.   The Comcast device has very poor facilities for diagnosing network problems or anything that might confuse the general Comcast users.  It gives a log that says there were some problems seen by the firewall and that's about it.

So we put the Asus device back in operation, switching the Cisco to bridge mode.  The Asus demonstrated the same IPv6 problems as before, but now it was time to scrutinize the log a little better.

We noticed a lot of ICMPv6 checksum errors like the following:

Jan 20 10:20:35 kernel: nf_ct_icmpv6: ICMPv6 checksum failed
Jan 20 10:20:35 kernel:  <0>nf_ct_icmpv6: ICMPv6 checksum failed
Jan 20 10:20:35 kernel: IN= OUT= <1>SRC=ff02:0000:0000:0000:0000:0001:ff6e:d2d3 DST=2601:0183:4002:0987:0000:0000:0000:0001 <1>LEN=64 TC=0 HOPLIMIT=255 FLOWLBL=0 PROTO=ICMPv6 TYPE=136 CODE=0

They repeat up to once a second, when they start coming. All the erroneous packets originated from the ...d2d3 address.  With a little work, we found...

The Guilty Party

The Amazon Fire tablet seemed like a good value at its ~$50 price.  Unfortunately, it appears to be sending the malformed IPv6 packets.  Powering off the Fire (or using airplane mode) cuts the errors, and seems to have stabilized the network.

Kindle's version of Android gives you very little to adjust, and you can't shut off v6.  We tried unloading most of the non-Amazon apps just in case one of them was causing the problem, but that had no effect.

Maybe $50 is just too cheap? That would be one moral of this story.

Another moral: Don't expect a Comcast router to help you fix your network if something goes wrong.

ARRL President's Award

Lots of comings and goings at the ARRL. Dave Sumner is retiring this year as CEO, and has just received the ARRL President's Award for his many years of service to the League, presented by outgoing President Kay Craigie.

Still slogging on Internet Issues

While trying to understand why IPv6 is (still) not reliable on my Comcast / Xfinity service, I rediscovered DSL Reports.  This is a great place to go to get your technical / support questions answered for DSL or Cable connections.

I have a post in for Comcast's attention.  Meanwhile, I ran the nice speed test tool, which gave me the highest-ever speed report.

More Network Fun: Asus, HP, and Xfinity

Asus RT-N66U (l), Cisco/Xfinity DPC3941T (r)

...in which we demote the Asus RT-N66U.

Faithful readers know about my efforts get reliable networking here at home (last post).  I want IPv6 to work well, and I'd like all my devices to freely work together, with good Internet access.

We took 2 steps forward, and then 1 back.  IPv6 worked, but not reliably when I set up the Cisco DPC3941T for "bridging mode" and gave the routing function to the Asus RT-N66U.  ICMPv6 packets were displaying lots of errors.

We ran the house that way for about a month.  Everybody was happy (in an IPv4 way), but there was one significant problem. Our HP LaserJet Pro MFP M127fw printer was not working reliably.

HP LaserJet Pro MFP M127fw

This is an "all in one" B&W laser printer / scanner / fax system offering lots of capability for a reasonable price.  It offers WiFi, Ethernet, or USB interfacing.

Everything works fine on Windows.  After a detour through HP's website, it works on Linux, too.  It works with Google's Cloud Print service, and HP's ePrint.

It worked for a while, but then would go catatonic and refuse new jobs after a period of minutes or hours.  You could always get it back by cycling the AC power.  We lived with this for some time, but it's pretty annoying to start a print job from the other end of the house, only to find out later that it did not go through.

So we tried a lot of tricks, adjusting the printer's setup, the router's setup, and even the Linux driver installation.  (The problem showed up with either Linux or Windows.)  We updated the printer's firmware. We tried both WiFi and Ethernet connections. 

Cut to the chase.  Eventually we cut out the Asus router, and there was progress.  Using the Cisco/Xfinity/Comcast router by itself, the printer worked -- and IPv6 worked, too!  It is clear that the Asus/Cisco combination (if not the Asus alone) is problematic for HP and IPv6.

So we retreat another half step.  We still use the Asus box as our main WiFi access point.  The Cisco 2.4 GHz WiFi transmitter is much weaker (nearly 20 dB weaker) that Asus, and it's built-in antenna system is doubtful.  (The Cisco box may actually be defective.)

For the moment, printing works, IPv6 works, and we will stop there.  The problems we had originally with Xfinity's DHCP and other issues of that sort are still there, but overall it's time to relax.