Tuesday, June 9, 2009

Are we looking at Interop here?

I had tough time sleeping yesterday. Its getting very humid here. I was thinking about LTE, mobiles and networks lying on bed trying to sleep. Then suddenly something stuck me, not literally :).

Can this blog become a platform for Interop testing? Interop is way too big for my blog. But if we think again, most of the people who visit blog are engineers. Developers, testers etc. We look for the answers in the web there by landing at the blog. You may get an answer or may not. But you are the one who is writing a piece of code for LTE to work.

I must say that 3GPP specs are no less then a rocky mountain to climb. Specs are not clear or they may not refer to each other well or we might have problems trying to figure out the things. But we will come up with a product. We try to interop our devices with other vendor devices. We may succeed or fail utterly. The beauty of 3GPP is we often fail. :) A simple IE can make things worse. Few months back we shipped our GTPv1 solution to one of our customers. We had release 7 Direct Tunneling feature implemented. Our product was well tested and everything looked great while doing in house testing. When customer started executing tests we fell flat on our face. When ever there was an update message indicating direct tunnel was passed, the vendors GGSN responded saying mandatory IE in-correct. Damn! A second look at the packets revealed that one of the IE's was sent wrongly. A simple 2 byte value wrongly sent and the whole feature was biting dust. We identified the problem and fixed it in no time. I went back to the specs and read them again. I misread the word "shall" to "may" and everything went wrong. The IE "shall" be sent was written not "may" be. That lead to a confusion, leading to issues in Interop.

Thats how critical Interop is at the ground level. Pickup a SGSN from one vendor and GGSN from other and there "may" be interop issues. So how do we validate the interoperability? Buy a test tool? May be. Or identify your potential customers and make sure that your product is working well with them. That needs a lot of planning.

with LTE interop is becoming big. Interop not only between multi vendor devices but interop between various technologies is coming into existence. There is some time left for interop but I am closely following the stories. The biggest problem in telecom industry is collaboration. Its tough for two companies to work hand in hand or share atleast share the information. This is what I know. Say, one company is manufacturing eNB and other is exclusively manufacturing EPC then who will do the interop testing between eNB and MME. Network service provider? The engineers will definitely have sleep less nights. I really want to see how interop will progress.

These are just some thoughts based on my experience. I am still a novice in the industry trying to get the big picture. :)

Corrections/Comments are welcome.


S.Kar said...

You are right. I was working with Nethawk for 10 yrs and as part of Test tool we normally develop the other end of the test suite to run. during our eNB simulation we develop MME and SGW so that we can do some compliance testing. It is again same mindset, mistakes may happen. when it goes out and inter-op with other vendors it is a real challenge. The most important is to read the spec very carefully and discuss with the vendor to get Interface document. for example incase of verizon LTE Deployment Ericsson does SGW, Camiant does PCRF, Starent does PDNGW and so on.

You are absolutely right 3GPP specs are sometimes really confusing. specifically in UTRAN domain. LTE is new and you see the revisions are coming so fast.

Santosh said...

Thanks Mr.Kar for insightful comments. Appreciated.

S.Kar said...

I Just started following your blog and it is really impressive. I have referred this to new comers coming to wireless domain to follow.

You are doing excellent job which i like most is you are breaking down the subjects into small areas and elaborate. lets discuss something about downlink packet handing on S5/S8 Interface (GTP / PMIP based). I hope GRE Key is used per PDN Connection and it is not per Dedicated bearer but GTP Tunnel is uniquely identify default as well as dedicated bearer. since i move to Ericsson I focus on offline so i am but outdated myself reading 3gpp spec but after reading your blog i again started reading. keep it up. really appreciate.

Santosh said...

Thank you for the kind words. They will keep me motivated. :)