Berlin home Internet link

More details on my Berlin Internet sitch. My apartment has a Technicolor router that comes from PrimaCom’s cable modem service. It was down entirely for several days (and not just for me) when we got here, which is not so awesome. Mobile hotspots are a poor alternative.

The downtime revealed PrimaCom manages the router WiFi. When the Internet was down the WiFi was also turned off. You couldn’t even turn it on in the admin pages (default login: username blank, password admin). Once Internet service was working again and I rebooted the router, I had WiFi. Weird.

The bummer about the router, or the larger network, is that it just forgets about idle TCP sockets after about 5.5 minutes. Idle ssh sessions and other quiet TCP links just stop working. Not even a reset, just a timeout, and it’s consistently timed so it’s not a FIFO queue filling up. There’s nothing in the router config that’s obviously causing the problem.

Of course web browsers never even notice, so most of their customers have no idea. I wonder if it breaks notifications via WebSocket though. For ssh I work around it with ServerAliveInterval=50. I suppose TCP keepalives would fix it in general but that’s a half-abandoned tech and the default interval in Windows is 2 hours (!) so you have to fiddle the registry. Ken has some weird TN3270 sessions he uses, I think SSL and telnet. We fixed his timeouts by just using Tunnelbear VPN which papers over the problem. I really should run my own VPN server.

We never could connect to an old school PPTP VPN. The TCP control channel for setup seems to have worked (according to Wireshark) but no GRE packets ever arrived.

The fun thing is I have an honest-to-goodness IPv6 address and all of it works. Sometimes I seem to be connecting to Google via IPv6. I’m not quite sure what to do with this capability, but it’s novel for me. I wonder if the router is still doing NAT for IPv6? The IP address a test site shows me is the same one my Windows box tells me I have, so I guess not. The router does have an “IPv6 firewall” enabled though, perhaps that provides basic protection from outside attacks? I should set up a remote IPv6 box to play around with this.

Update: Primacom seems woefully underprovisioned. In the morning I get about 5000kbps, bursting to 10Mbps. In the evening I’m doing good to get 500kbps, 1/10th the speed. I assume that’s contention with my other cable modem users. 500kbps isn’t really enough to even stream video.

 

Here’s a traceroute on IPv4

|------------------------------------------------------------------------------------------|
|                                      WinMTR statistics                                   |
|                       Host              -   %  | Sent | Recv | Best | Avrg | Wrst | Last |
|------------------------------------------------|------|------|------|------|------|------|
|                             192.168.0.1 -    0 |    3 |    3 |    2 |    5 |   10 |    5 |
|                              10.195.0.1 -    0 |    3 |    3 |   10 |   20 |   41 |   41 |
|                            172.16.0.201 -    0 |    3 |    3 |   15 |   24 |   42 |   42 |
|                            172.16.0.109 -    0 |    3 |    3 |   15 |   24 |   42 |   42 |
|                             172.18.0.53 -    0 |    3 |    3 |   16 |   25 |   43 |   43 |
|        ae63.edge7.Frankfurt1.Level3.net -    0 |    3 |    3 |   24 |   30 |   43 |   43 |
|   ae-2-3210.edge4.Frankfurt1.Level3.net -    0 |    3 |    3 |   30 |   34 |   44 |   44 |
|             10ge10-15.core1.fra1.he.net -    0 |    3 |    3 |   27 |   35 |   50 |   50 |
|              100ge5-2.core1.par2.he.net -    0 |    3 |    3 |   74 |   81 |   93 |   93 |
|             100ge14-1.core1.nyc4.he.net -    0 |    3 |    3 |  114 |  124 |  143 |  143 |
|              100ge9-1.core2.chi1.he.net -    0 |    3 |    3 |  143 |  156 |  163 |  143 |
|             100ge12-1.core1.mci3.he.net -    0 |    3 |    3 |  141 |  154 |  162 |  141 |
|               10ge4-1.core1.mci2.he.net -    0 |    3 |    3 |  142 |  155 |  163 |  142 |
|wholesale-internet-inc.10gigabitethernet1-3.core1.mci2.he.net -    0 |    3 |    3 |  142 |  155 |  163 |  142 |
|lag-to-oak.edge-a.clay1.mci.us.as32097.net -   34 |    3 |    2 |  160 |  161 |  163 |  160 |
|lag-core-b.dist-1-3.clay1.mci.us.as32097.net -    0 |    3 |    3 |  146 |  156 |  163 |  146 |
|                         wk.somebits.com -    0 |    3 |    3 |  145 |  157 |  163 |  145 |
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