Tag: wlan

ICS expe­ri­ence on the Sama­sung Galaxy Tab 10.1

As told before, I have the ICS as pro­vid­ed by Sam­sung (to it is not the stock ICS, it is the Samsung-version of ICS)  on the Galaxy Tab 10.1. Now that it is near­ly two months of using it, I want to share a lit­tle bit of my experience.

Basi­cal­ly it just works. If you know ICS already, you more or less know how it is on the Galaxy Tab 10.1.

The cal­en­dar app is dif­fer­ent, it is the Sam­sung app, not the native ICS one. I have a prob­lem to sync it with the exchange-connector as it is in Horde 4, but I did not take the time to inves­ti­gate the issue. My Nexus S con­nects just fine, so it must be some mod­i­fi­ca­tion by Sam­sung which is caus­ing the issue.

Some­times the tablet hangs, and I have to shut­down by press­ing the pow­er but­ton for some sec­onds. This only hap­pens when con­nect­ed via WLAN. When I start the tablet again, it will hang again if I am not fast enough to enter the PIN of the SIM, unlock the screen and to deac­ti­vate the WLAN. But even then it will hang after the deac­ti­va­tion of the WLAN. After reboot­ing the sec­ond time (with WLAN already deac­ti­vat­ed), every­thing works again.

The email app is also stut­ter­ing some­times. This hap­pens when I open a fold­er with a lot of emails and the email app is try­ing to deter­mine if there are attach­ments or not. Either the app is not multi-threaded, or it is not well done.

Apart from that it just works.

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How big are the buffers in FreeB­SD drivers?

Today I have read an inter­est­ing inves­ti­ga­tion and prob­lem analy­sis from Jim Get­tys.

It is a set of arti­cles he wrote over sev­er­al months and is not fin­ished writ­ing as of this writ­ing (if you are deeply inter­est­ed in it go and read them, the most inter­est­ing ones are from Decem­ber and Jan­u­ary and the com­ments to the arti­cles are also con­tribut­ing to the big pic­ture). Basi­cal­ly he is telling that a lot of net­work prob­lems users at home (with ADSL/cable or WLAN) expe­ri­ence  are because buffers in the net­work hard­ware or in oper­at­ing sys­tems are too big. He also pro­pos­es workarounds until this prob­lem is attacked by OS ven­dors and equip­ment manufacturers.

Basi­cal­ly he is telling the net­work con­ges­tion algo­rithms can not do their work good, because the net­work buffers which are too big come into the way of their work (not report­ing pack­et loss time­ly enough respec­tive­ly try to not lose pack­ets in sit­u­a­tions where pack­et loss would be bet­ter because it would trig­ger action in the con­ges­tion algorithms).

He inves­ti­gat­ed the behav­ior of Lin­ux, OS X and Win­dows (the sys­tem he had avail­able). I want­ed to have a quick look at the sit­u­a­tion in FreeB­SD regard­ing this, but it seems at least with my net­work card I am not able to see/find the cor­re­spond­ing size of the buffers in dri­vers in 30 seconds.

I think it would be very good if this issue is inves­ti­gat­ed in FreeB­SD, and apart from maybe tak­ing some action in the source also write some sec­tion for the hand­book which explains the issue (one prob­lem here is, that there are sit­u­a­tions where you want/need to have such big buffers and as such we can not just down­size them) and how to bench­mark and tune this.

Unfor­tu­nate­ly I even have too much on my plate to even fur­ther look into this. 🙁 I hope one of the net­work peo­ple in FreeB­SD is pick­ing up the ball and starts playing.

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IPv6 in my WLAN

The man­u­fac­tur­er of my WLAN router released a new firmware. It con­tains IPv6 and DNSSEC sup­port. I got a lit­tle bit of time and pow­er to install it. Unfor­tu­nate­ly my ISP does not pro­vide IPv6 connectivity.

I have now installed the IPv6 sup­port in Win­dows XP for the Net­book, cre­at­ed (and reg­is­tered) an ULA pre­fix at SixXS, and ver­i­fied that the net­work stack of XP gets it from the WLAN router.

When I do an IPv6 ping from the lap­top to the router, it works, but the IPv6 address does not show up in the Home­net­work overview of the router. Seems they still have some work to do.

Regard­ing DNSSEC I do not see any options in the man­age­ment inter­face, but I assume it just means that the DNS serv­er does the right thing when he is con­front­ed with recur­sive DNSSEC requests. No idea if he will val­i­date him­self and if yes, if he will add some log mes­sages regard­ing it or not.

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The ben­e­fits of a WLAN

The nice thing about WLAN is, that you can fol­low the instruc­tions of your Doc­tor (“go to bed, sweat a lot, that is the only thing you can do to heal”), and at the same time you can do some­thing if you get bored and have the pow­er to do some not so dif­fi­coult read­ing (if you do not accept a TV in the bed­room like me).

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