cisco CSG/GGSN + more DNS applications

So once upon a short time back I worked on the mobile core (I still insist thats the best team to work with - ever). The interface between the sgsn and the GGSN is called the gn interface. (I promise to do more posts on the mobile core).

Now our GGSN's were actually a couple of cisco MWAM blades hosting several ggsn's each.

We used DNS for load balancing traffic from the sgsn to the ggsn. Here's a brief of how it works:

during session setup also known as pdp context activation, the sgsn is supposed to set up a tunnel (gtp tunnel) with a ggsn for each  session. Now the user uses an 'apn' like 'safaricom' which defines the service a customer is allowed to access. each ggsn is configured to allow a specific apn access, the sgsn looks at the apn, checks a dns server, resolves the apn to a ggsn's ip address and creates the tunnel.

DNS is therefore used to decide which ggsn to channel the request to. Multiple DNS servers means you get to load balance the traffic among the ggsn's - round robin. It was not perfect, but it was cheaper than trying to get loadbalancers in.

If you'd like to know more about how the mobile core works, how its all put together drop a comment ....the design considerations are definately way more than trying to slap together a document for a pure IP core....

Cisco SAMI blades....and ASA 5580's

I have worked for the last 3 or so years now with the cisco GGSN/CSG aka CMX (Cisco Mobile Exchange) supporting gsm,gprs and UMTS on the 7613 platform.

The old boxes were getting sort of old and tired, They also have the new ASR5000 (starent acquisition) that I believe to be by far more superior than what they were pushing.

Anyway pending some decisions, cisco being the nice guys they are actually sent some brand new toys for me to test. Please see attached....this is going to be a great week:-) I get to lab up the entire topology and integrate the new toys:-)

**Last three images are the sami blades







I also get to play around with the Cisco ASA 5580 with GTP inspection licence. Now this has been on my wish list for a while now. Swapping out the almost old firewalls for re-deployment will be easy. The fun is mainly in the higher number of supported interfaces and their capacity (10G), the gtp inspection will save our GGSN's quite alot of resources....oh well some photos (yes I opened them up to see what's in there).....

I'll post a review of both next time.....
I have some requests for easy to understand terms when dealing with gsm/gprs/umts mobility....I'll see about that too...Its just so wide I don't know where to start so if you have some ideas please let me know....