Nearly all the operators I have talked to who are deploying IMS networks are using SBC's (mainly from Acme Packet). I have noticed a trend where many of these operators, especially the smaller ones, are not doing much testing of the situations described in Chapter 4 because they have an SBC and "that's what the SBC does". As a reminder, the book covers the following topics in Chapter 4:
- Outage Recovery,
- Peer network floods, and
- Malicious attacks like DoS, Registration hijacking, and CallID spoofing
Yes, SBC's are designed to deal with many of these problems and they typically do a good job of it. But is your core network designed to deal with the SBC? SBCs are complex devices that require a lot of configuration. The goal of testing these scenarios is not to break the SBC, but to ensure the SBC is properly configured and optimized for your environment.
Using the Power Outage Restoration example, the SBC can throttle messages sent to the Core, but how do you know what your core can handle? What about the customized application you are running? Your system integrator will likely be very conservative and go with a low number, but this could lead to unnecessary capacity upgrades when they are not needed. A few relatively simple tests can help to answer these questions and keep your integrators/vendors honest.
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