Tag Archives: network

Bluetooth!

Posted on by
Reply

For a long while now I have been having intermittent problems with the audio in my lab. I stream the GoaPsy channel from di.fm, and I really love it, but not when there’s skipping! I figured the problem was related to latency and jitter on my broadband connection, and if so, there was little to be done, except to wait for network conditions at my ISP to change.

But this evening I noticed that when I sat close in to my workstation to type the skipping would start. Then if I moved back in my chair, it would stop. I found I could actually cause the skipping to start or stop just by moving around in my chair!

Turns out the problem wasn’t my internet connection, the problem was the bluetooth connection between my laptop and my speakers! To fix the problem I got underneath my desk and moved my sub woofer about one foot to the left. Now when I move around in my chair my music doesn’t skip anymore! Happy days!

Network v4

Posted on by
Reply

I have redone my computer network in its fourth (and final?) incarnation. Everything got redesigned from the ground up. You can see some of the (color coded!) cabling here:

The two switches on top (GREEN and ORANGE) support speeds up to 2.5 Gbps, whereas the bottom two switches (RED and BLUE) only support up to 1 Gbps. The white cables on the right are spares, they’re just auxiliary cables which have already been installed and are available if I need them in an emergency.

Fixing Firefox/Iceweasel restricted port

Posted on by
Reply

Today I ran into this warning from iceweasel when I tried to access a web service on port 101:

This address is restricted

This address uses a network port which is normally used for purposes other than Web browsing. Iceweasel has canceled the request for your protection.

I found this article which said:

  • Open about:config
  • Create network.security.ports.banned.override if it’s not there
  • Set that setting as, e.g.: 101-104
  • Refresh the page

1000baseT for RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller

Posted on by
Reply

I have a Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06) in my new Ubuntu Trusty (14.04.1) server. As you can see here:

root@orac:/home/jj5# lspci
...
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)
...

I was having a problem with the card only supporting 100baseT speeds. I downloaded and installed the Realtek driver (and rebooted):

# bunzip2 r8168-8.039.00.tar.bz2
# tar xf r8168-8.039.00.tar
# cd r8168-8.039.00
# ./autorun.sh
# reboot

That didn’t fix the problem.

I installed the ethtool package and ran it:

# apt-get install ethtool
# ethtool p2p1
Settings for p2p1:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Full 
        Supported pause frame use: No
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Full 
        Advertised pause frame use: Symmetric Receive-only
        Advertised auto-negotiation: Yes
        Speed: 100Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: on
        MDI-X: Unknown
        Supports Wake-on: pumbg
        Wake-on: g
        Current message level: 0x00000033 (51)
                               drv probe ifdown ifup
        Link detected: yes

As you can see the speed is 100Mb/s, not 1000Mb/s. It says that 1000baseT full duplex is supported. I tried forcing the speed:

# ethtool -s p2p1 speed 1000 duplex full advertise 0 autoneg off

But that didn’t work. The ethtool program reported the card was still operating and 100Mb/s.

Then I tried plugging in a different cable… and that fixed the problem!