Author: otmar

Buying shoes for kids

Post author By otmar
Post date February 28, 2009

The feet of kids are delicate things and as a caring parent you’re supposed to make sure that the spawn’s footwear fits his ever-growing feet. Ok, spring is coming and thus the time is near where we can stop using his #24 winter boots and give him “normal” shoes again. So off to the store we are and what do we find?

At the end of February, the shop is already geared towards summer shoes. i.e.: open shoes and sandals. Great. That’s about 2 to 3 months in the future.

That stocking policy might make sense for shoes for adults, but for kids? The size of their feet is highly variable. You buy when you need the shoes as you want to size them correctly.

So dear shoe industry: what’s fine in the woman’s section of the store does not make sense in the kids section. There, “just in time” shopping is much more appropriate. Please stock accordingly.

IETF

IETF drinks: Regarding domains in usecases-02

Post author By otmar
Post date February 26, 2009

I’ve written about this already a few times in various IETF / RIPE lists, but it seems to be relevant to the current draft as well, so here is a repeat:

According to the usecases draft, SSPs report the public identities of their customers to the registry so that the registry can store the mapping to destination groups. All fine and dandy for TN based public identities, but what about sip:user@domain?

These URIs come in (at least) two flavors:

a) the domain is the provider’s domain (e.g. “verizon.com”)
b) the domain is owned by the customer (e.g. “shockey.us”)

The first one makes it easy for the SSP to authoritatively tell the registry that it provides service for whatever URI it is going to provision. So from the point of drinks, this is easy.

[I still very much doubt that solely offering such PIs to customer is dangerous to the SSPs as they might be forced to offer PI portability, which would really mess up a lot of assumptions.]

So what about b)? Portability is a given, and ISPs are used to deal with customer-owned domains for email and web. Good. So what’s the authorization mechanism? For email and the web it’s simple: the entity which controls the domain must set the respective MX and CNAME/A records so that the rest of the world know who provides email/web services for this domain. If the control over the domain changes, so does instantly change the control over email and the website.

Now, if a SSP can provision any URI regardless of the domain ownership status / domain content, this opens up a pandora’s box of interesting errors. We now duplicate who operates SIP service for a domain in two databases which can and will run out of sync with each other.

I consider it thus a lot more in line with the rest of the Internet protocols to store the mapping domain -> destination group in the DNS and not some other registry.

IETF

Some comments on draft-channabasappa-drinks-usecases-requirements-02

Post author By otmar
Post date February 25, 2009

Richard wants feedback, so here it comes.

This document is a _lot_ better than -01. Much more consistent.

Overall impressions:

This is a telco design. Basic bell-head thinking with only some marginal sprinkling of Internet ideas. This is a document which describes how one might carry over the telco provisioning, interconnection and call routing approaches to the VoIP world.

All fine and good, but to be provocative: why is this an IETF WG document and not an ITU-T, OASIS or 3GPP paper? The role model, the actors and a most use-cases are almost straight from the PSTN playbook.
This is way too ambitious on one hand. Defining all this in a single protocol and implementing the registry which actually does all these things is a herculean task.
Layering, folks. Layering.

Divide the problem into discrete, clearly separated sub-problems (see the speermint LUF/LRF split for a good one) and the complexity can be brought under control.
This is way too conservative on the other hand. There is little dynamic routing. There is no integration of enterprise VoIP routing with carrier routing. There no possibility of ad-hoc peering.

Okay, some specifics:

System Administration

Windows XP: Doh.

Post author By otmar
Post date February 22, 2009

Letzte Woche:

Windows: Starten Sie neu

Verarschen kann ich mich selber.

Pet Peeves

Kafka would be proud

Post author By otmar
Post date February 22, 2009

I used to work for KPNQwest, which was a pan-European company. They tried to offer seamless service across Europe (which failed miserably) and tried things like regional service centers.

Dealing with Interxion gives me Deja-Vues. They, too, try to offer the same service in all of their Datacenters across Europe. And they, too, have their centralized customer care. Here the fun starts:

Tracks

Train Tracks

Post author By otmar
Post date February 2, 2009

track 2009-02-08

This one started with a plain rounded square and then started to branch out.

Life Pet Peeves

Buying a new TV set

Post author By otmar
Post date January 2, 2009

I had hoped to replace my old CRT in a few years when the pace of innovation on the LCD side had settled down, the standards have really established themselves, more HD content feeds are available, and the prices are lower than now. But no, the CRT called it quits a few weeks ago (no more vertical beam deflection) and we are forced to buy now.

Well, shucks.

I won’t repeat what’s been discussed to death in the various videophile sites and price-comparison fora. Just one simple question:

Why don’t hand the shops out simple 1:1 scale paper pictures of the various TV sizes? It is really hard to picture how the set you see in the showroom will look like in your living room and thus decide which size you want to buy.

Thus I spent yesterday evening getting the measurements of 32, 37 and 42 inch TVs and cutting cardboard as mockups. Holding these against the wall almost instantly told us what size we really need/want.

So dear Philips, Sony, Toshiba & co: what about it?

Internet

Some thoughts on .tel

Post author By otmar
Post date December 4, 2008

Last week Carsten Schiefner talked about .tel at the nic.at Registrartag in Vienna. Now that .tel has finally launched, here are my thoughts on this new TLD:

Austria Life

East / West and counter-intuitive train stations

Post author By otmar
Post date November 29, 2008

I was booking train tickets from Vienna to Budapest this week and noticed the following absurdity:

My train from Vienna to Budapest leaves at Wien Westbahnhof and arrives at Budapest Keleti pályaudvar. In other words, I’m leaving from the western train terminal in Vienna and will arrive at the eastern train station in Budapest.

So far, so good.

It’s just that Budapest is straight to the east of Vienna.

(Yes, there are good reasons for that, for the Vienna side it’s that the train is coming from Zurich. In Budapest Keleti seems to be the default station for international trains.)

Pet Peeves

Numerology and Haider’s death

Post author By otmar
Post date November 16, 2008

I spent this weekend in Carinthia and got treated to the local press. The KTZ had on their front-page a story about a numerologist who had calculated that Haider was in great danger during October and November. She had tried to warn him, but they didn’t manage a meeting before his date with a concrete fence post.

As usual, the story did not ask the only really relevant question: How many other calamities had she predicted in her career that did not came to pass?