, 19 tweets, 11 min read Read on Twitter
Today we are going to talk about the mobile network backbone and how we passed from #photo to something which has not phyisical existence because it's in a #Cloud. The thread is going to be about #technology, but we are going also to start by #History of the #telecommunications👇
The backbone of the mobile network is the Signal Transfer Point (STP for GPRS and 3G) or the Diameter Routing Agent (DRA for LTE, which was a jump from the older technologies). But let's see where this started and how we have the current scenario 👇
STPs are like an IP router... but it work with sinalling protocol (SS7). Before the companies of the US fed up and imposed the IP/TPC that today everybody knows with their market power the things were done in a more #telco way: through international standarization 👇
In this way, and remember than telephone were too much older than the IP/TPC world, the ITU (dependent of the UN) decided to define a crazy standard of telecommunication... which was applied: the OSI model 👇
So SS7, which because the STPs continues being a main protocol of the Mobile Networks (so also the #IoT one as we explained here twitter.com/i/moments/1097…) started with non-IP protocols 😱👇
SS7 was invented by @ATT (and standarized by @ITU) in order to secure an issue with the old signalling systems in telephony, which can be hacked whistling in the device. Here you can find the history of the perhaps more famous hacker in this way es.wikipedia.org/wiki/Joybubbles 👇
So let's focus in STPs again. Considere that when you send a whatsapp message or you are registered in a mobile network the information of your handset cand travel accross a country or, in fact, many (in roaming). This information travels because it's routed because the STPs 👇
But as you don't have IPs (at first) when you configure a communication btw STPs (in order your #IoT device can do something) you need to establish a linkset in a very crazy way: using something called Point Codes (instead of IP Addresses) for sample 👇
Above the Point Codes there are other routing parameter: the Global Titles. These are ficticial mobile numbers which are created through a transformation of the IMSI identificators of the SIM cards 👇
infobip.com/en/glossary/gl…
It's typical in a mobile network split the traffic because the kind of SIMs (everyone of them is identified with a number, called IMSI, which is different of your telephone number and it's used by the #telco operators) 👇
For sample: typically traffic of #IoT SIMs and user's ones is splitted. As #IoT SIMs have their own IMSI range it's possible to establish a rule based in the GTs of one and others and send the traffic to different network elements (as HLRs for sample) 👇
But SS7 was too crazy and have a different network, once IP was imposed in all that already is known as Internet, was a real problem. Keep in mind that if we want merge mobile network with IP one GWs would be mandatory (and in fact they still are) 👇
So because that reason SS7 was redefined to work over IP (the current status of this protocol) and it was called Sigtran (not confuse it with the voice technique Siptrunk). In this #photo you can see the equivalence with SS7 👇
But it continues being rather crazy because the OSI definition of 30 years ago. So when LTE was started to be created @GSMA decided to bury that idea. All the protocol stack changed to an evolution of the Radius (doble Radius): Diameter 👇
If you go to this last image and the first ones of SS7 you can see it is very different. But further more, now with #5G this is going to change again and we are going to have HTTP to communicate the network elements... emulating the current API paradigms. 👇
Diameter is very curious because how an Authentication protocol (at its begining) as Radius has been readapted to cover general #telco communications. In a DRA (the STP in a LTE network which manages this protocol) configuration is also easier 👇
As we can route directly using the IMSI. Routing in one of these devices work through database tables. A table stores the linksets (this still exists), other stores rules because origin, other because destination, other because IMSI ranges...combining all of them decide linkset👇
The aspect of a STP or DRA is like this. Too much small than the #photo of the begining... but keep in mind that today a DRA doesn't exist: they can be stored in a #Cloud and Cloud is also the basis of the #5G system 👇
So I hope than next time you think in an #IoT deployment or you send a whatsapp message think, more or less, in all the huge machinery which is behind of it and how it works in milliseconds. Now I've realized that #RealMadridBarça are already playing. Finish this thread. C u
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