An IMS Analysis Challenge – Find the answers to the questions through analysis of PCAPs.
What’s the biggest speed you can punch into the speed fields in LTE and 5G?
A look at how PyHSS handles fixed line subscribers attaching to an IMS Network
Getting to know the GSMA’s TAP files, what’s in them, and how they’re used to bill roaming traffic.
A look at how the SQN resync procedure is performed in the IMS Authentication flows
A look at the PCRF in EPC Networks, and the Charging Rules that lay at the heart of it all.
Using Kamailio with a Diameter Routing Agent
Using FreeDiameter, Python and our newly released “rt_pyform” module to rewrite AVPs in your FreeDiameter based Diameter Routing Agent.
An overview of the who, how and why of Non-IP Data Deliver in NB-IoT cellular services.
A look at why we’d want to apply translations to Diameter AVPs inside a Diameter Routing Agent
Looking at overriding the default Diameter routing logic in FreeDiameter with rt_default
Using FreeDiameter as a DRA
Diving back into the world of Diameter Routing Agents with a look at the logic that defines how a DRA routes traffic from one place to another.
Answer Question 1: Because they make things simpler and more flexible for your Diameter traffic.
Answer Question 2: With free software of course!
All about DRAs
But let’s dive a little deeper. Let’s look at the connection between an MME and an HSS (the S6a interface).
We configure the Diameter peers on MME1 and HSS01 so they know about each other and how to communicate, the link comes up and presto, away we go.
But we’re building networks here! N+1 redundancy and all that, so now we have two HSSes and two MMEs.
Okay, bit messy, but that’s okay…
But then our network grows to 10 MMEs, and 3 HSSes and you can probably see where this is going, but let’s drive the point home.
Now imagine once you’ve set all this up you need to do some maintenance work on HSS03, so need to shut down the Diameter peer on 10 different MMEs in order to isolate it and deisolate it.
The problem here is pretty evident, all those links are messy, cumbersome and they just don’t scale.
If you’re someone with a bit of networking experience (and let’s face it, you’re here after all), then you’re probably thinking “What if we just had a central system to route all the Diameter messages?”
An Agent that could Route Diameter, a Diameter Routing Agent perhaps…
By introducing a DRA we build Diameter peer links between each of our Diameter devices (MME / HSS, etc) and the DRA, rather than directly between each peer.
Then from the DRA we can route Diameter requests and responses between them.
Let’s go back to our 10x MME and 3x HSS network and see how it looks with a DRA instead.
Not only does this look better, but it makes our life operating the network a whole lot easier.
Each MME sends their S6a traffic to the DRA, which finds a healthy HSS from the 3 and sends the requests to it, and relays the responses as well.
We can do clever load balancing now as well.
Plus if a peer goes down, the DRA detects the failure and just routes to one of the others.
If we were to introduce a new HSS, we wouldn’t need to configure anything on the MMEs, just add HSS04 to the DRA and it’ll start getting traffic.
Plus from an operations standpoint, now if we want to to take an HSS offline for maintenance, we just shut down the link on the HSS and all HSS traffic will get routed to the other two HSS instances.
In our next post we’ll talk about the Routing part of the DRA, how the decisions are made and all the nuances, and then in the following post we’ll actually build a DRA and start routing some traffic around!
Using OpenSSL to generate self-signed certs for use in FreeDiameter
A simple trick to find all the system paths used in FreeSWITCH
In our last few posts we got CGrateS setup in order to have rates and tariffs in the system, so we can price a call. Where we ended we were able to use the APIerSv1.GetCost method to get the cost of a call, and today, we’re going to actually create some rated CDRs. So again … Continue reading CGrateS in Baby Steps – Part 4 – Rating Calls
Finally rating a call end-to-end with CGrates!
CGRates in Baby Steps – Part 2 – Introduction to the CGrates API
Getting started with CGrateS to bill for calls in a Telecom environment.