from Chips to Chips

I’ve been using XMBC on the XBOX for several months now… (yes it’s kinda late) but hey, it still rocks!!

Then recently, I moved the XBOX to the living room and for some reason the MP4 files would not play anymore. Everything else worked fine… but not MP4. I spent over a month troubleshooting it, re-installing XMBC, etc.. nothing worked. All I knew was that these files would play, when the XBOX was in my study & in the bedroom.

Finally, I was shown the light, by someone a lot less techy than me… my wife. I lamented to her about the unexplainable problem I was having with the XBOX. Then she asked… “is it because of the TV?” That literally lit up the bulb in my head and it lit up the path to the solution.

So, how does the TV have anything to do with the XBOX? What ever the XBOX should not be dependent on the TV. So, up front, that theory should have gone out the window… but not exactly. It was due to the TV, or rather… the xbox is connected to the TV using component cables. Everywhere else was using regular RCA. So… what’s the difference?

The difference was 1080i. Because the XBOX was using component cables, I had it configured to go up to 1080i. So, I turned of all hi-def resolutions (480p, 720p & 1080i) and tried. The movie played flawlessly. It was just that simple!! Further testing confirmed that MP4 would play in 480p and 720p… but not 1080i. That’s good enough… since my MP4 were all standard def anyway.

So, the month long troubleshooting, network testing, performance tuning, all went no where. It was simply just the XBOX settings for the TV.

Definitely learnt a new lesson about checking on the basics… even if it’s seemingly unrelated.

All thanks to my dear wife, Winny =)

ever since I upgraded my iPhone to OS3.0, I’ve been having trouble trying to get PPTP VPN to work. Never had the time to seriously look at it until now.

My VPN end point is a Linksys WRT54GL running with DD-WRT. I know that PPTP service works there as I can connect with my notebook, even with my 3G dongle.

Initial findings pointed towards the support for encryption on the DD-WRT implementation, and it has to be forced to “none” on the iPhone. Even that didn’t work.

With the release of OS 3.1, I started to tether my notebook to the iPhone, and through that, the PPTP will fail. That stumped me! Initially I thought could be due to the NAT implementation to enable tethering.

With trial and errors, I found out that over a WIFI connection, PPTP connection will work. Did I forget to mention that CISCO based IPSEC VPN to my office network works nicely over cellular and WIFI? That really baffled me. So, there’s something that’s in place that only works for IPSEC over cellular.

Finally, I came across some forum postings that lead me to the solution. There are many other people with similar issues in Canada and USA, and for some, they are able to tweak their APN on the phone to a different one and it worked for them. Of course they needed to be on different data subscription etc… for that to work.

I’m in Singapore, and my cellular provider is SingTel. I whipped out my iPhone 3GS and compared it’s APN settings to my 3G dongle for my notebook. Wallah! they are different, even though they are both with SingTel. I swapped in the new APN settings on to the iPhone, and PPTP started to work.

So, for all those in Singapore and on SingTel with similar needs and issues, the solution is to change the APN from “e-ideas” to “internet”. And here’s SingTel’s official instructions. BTW, these instructions are generic for all data devices.

For everyone else, what I realize from this is that some services/ports are controlled by the service provider. So, just by changing the APN won’t work if you don’t have access to the relevant APN.

If you need some guide on how to set your APN on your iPhone, the official Apple guide is found here.

*update 2009 Oct 09* after changing the APN, the “tethering” feature disappears. But if I reset the “Cellular Network” settings, “tethering” comes back. Got to figure out how to enable both.

if you’ve ever setup a network and handled IP address allocation, more often than not, you may try to remember the network addressing in your head.

C’mon, how many people out there really document what you do. Techies are well known to not document what we do. Just about very often, we’ll end up forgetting what we have done before. When ever we have to revisit the environment, we’ll need to dig deep into our memory, hoping we can recall our work.

Face it, even I have learnt the lesson of not documenting. Age is catching up and memory is not as good as it used to be. Now, the very least I’ll document the important stuffs.

So, how’s this related to IP address management? I see it simply as documentation of IP address usage. If you do document your IP addresses, I’d guess you’ll probably be using an excel spreadsheet. Heck, a lot of people I know uses excel spreadsheets to track IP address allocations.

Such a document is critical to keep up to date, and you’ll need good team discipline to keep the information current. All you need is just one, yes one, slack in the updates and hell can potentially break loose.

So, here I have stumbled upon a nice tool released by Solarwinds. My network engineer once told me that Solarwind products are very powerful and useful to manage large networks. I never had the chance to experience it, but I’ve played a little with this niftly little free tool they have, the “IP Address Tracker”.

This free version runs standalone, and capable of scanning the given subnet for all IPs which are online at the time. If SNMP is enabled, it will also tryto automatically pick up some details regarding each device. You can also flag each IP manually to categorize them, in addtion you can certainly put down little comments for every address. It will also keep track on the current latency of the IP, the last known date and time it was reacheable.

The user interface is pretty straighforward, and I like it. I use it personally to help me document the few home networks I’m helping to up-keep for my family.

Now, it gets even better, this tool has a paid version which can integrate into the Solarwinds suite of tools. I haven’t seen how it works, but some features I’ve read include running the app as a service, so it can do a realtime tracking of used IP addresses. In addition, it will provide a web interface, meaning a team of network engineers can potentially use it at the same time. That’s my favorite bit, real-time automated documentation and tracking of IP addresses being used.

This tool can certainly save time and effort for network engineers.

With all these said, this tool is only for those networks which allows (I assume) ICMP pings. Otherwise, excel will be your best friend.

For a techie like myself, I tend to prefer devices which are less of an all-in-one design. These devices though reduces the clutter you may have, but makes the situation more restrictive when you want or need an upgrade. You’ll end up having to either find a new device which has all the functions, or you’ll need to start to break them up.

This is especially true for my home broadband connection. I don’t like to use an all-in-one modem/router/wifi device. Although I don’t have a choice to use one provided by my ISP,  as I need it for the VOIP function it provides, but I still use another router to perform the routing function.

So, I have a 2wire 2700HGV-2, it’s a VOIP/WIFI/DSL Modem/Router rolled into one. I only use it for the VOIP and DSS Modem function. For Router, I use a Linksys WRT54GL (with a 3rd party firmware hack).

Don’t trust my 2700HGV-2 to do everything, as it ends up hanging every other day. With this combination, my overall setup runs more stable. And on top of that, I have a great router that does a lot more.

How about giving you a day by day chart on your internet usage volume, a realtime chart on your network & internet traffic, or the ability to create more SSID for your home WIFI network, for those times when a friend visits, needs to have internet access on his iPhone, but you want to only grant him “guest” access? These are features of commercial routers which are at the cheapest, several hundred dollars.

The Linksys WRT54GL costs under S$88 and DD-WRT (the 3rd party firmware) is free! [donation to the developer is available if you like the firmware]

You just need to download and re-flash the firmware and you’ve upgraded your S$88 router to be capable of features found in a US$399 router!

I’ve been using DD-WRT for a few years now, and I totally like the stability and what it can do for me. In fact, one of my main reasons that I encourage my friends to use it is to setup bridged wireless networks.

My next upgrade to my router will definitely a router capable of running DD-WRT, and provides good wireless N performance.